I make this call to a static singleton instance from the class GameManager.java
.
HUD.getInstance().update(timeDelta);
HUD.java
contains the HUD
class as well as two other related classes, HUDTextElement
and HUDElement
. All the classes are in the same root path ../src/org/mypackage
.
However, when compiling this project in IntelliJ I get cannot find Symbol HUD on the line I make the HUD.getInstance()
call.
This exact same code compiles just fine in Eclipse, any idea what the problem is?
2240
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asked Aug 26, 2012 at 16:50
2
Select Build->Rebuild Project will solve it
answered Dec 10, 2016 at 5:34
tibootiboo
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10
I had the same problem and fixed it by clicking File>Invalidate caches/ restart
answered May 10, 2016 at 10:03
ganninu93ganninu93
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3
I had the same problem, and turns out I had never completely compiled the fresh project. So right-clicking and selecting Compile» (shift-cmd-F9 on mac) fixed it. It seems the compile on save does not ‘see’ non-compiled files.
Marking the src folder as source did not help in my case.
answered Mar 6, 2013 at 9:13
Sjoerd KSjoerd K
7095 silver badges2 bronze badges
0
This is likely to be your ../src folder is not marked as a «source» folder in Intellij IDEA, so it doesn’t know to look there to find your class. You can right click the folder in the project explorer and choose «mark as source folder» to fix this.
answered Aug 26, 2012 at 16:54
Paul SanwaldPaul Sanwald
10.8k6 gold badges44 silver badges59 bronze badges
5
I was getting the same «cannot find symbol» error when I did Build -> Make Project
. I fixed this by deleting my Maven /target
folder, right clicking my project module and doing Maven -> Reimport
, and doing Build -> Rebuild Project
. This was on IntelliJ Idea 13.1.5.
It turns out the Maven -> Reimport
was key, since the problem resurfaced a few times before I finally did that.
answered Oct 13, 2014 at 18:43
Christian WilkieChristian Wilkie
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1
For me — I tried these steps(Invalidate Cache & Restart, Maven Reimport)) but they didn’t work. So I deleted the .idea
, .settings
, and .project
folder and tried — it worked.
answered Oct 25, 2019 at 22:38
R11GR11G
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3
I faced the same problem, and there are a lot of solutions given in the answer, trying all these solutions took me quite some time, so here I would like to propose a methodical approach if you get this error.
Check for the following things, create/update if something is missing
- src folder is marked as the source folder
- .imls files are present
- Annotation processing is enabled
- If you recently used @UtilityClass then it can also be the reason, Bug Link
If everything is fine, you can try following solutions in given order
-
Recompile the file/module
-
If that didn’t fix the issue, try refreshing maven dependency and building the project using
Maven -> Reimport
andBuild -> Rebuild Project
-
Try
mvn clean install -DskipTests
-
Try invalidating the IntelliJ cache and restarting the IDE, using
File > Invalidate caches/ restart
-
Delete the .idea folder and reimport the project
Credit and Thanks to everyone who answered this question, you can refer to their answers for more description regarding each point.
answered Jun 18, 2020 at 11:10
Deepak PatankarDeepak Patankar
2,9912 gold badges16 silver badges33 bronze badges
1
I solved this problem doing right click on Java Folder and Rebuild
answered Nov 22, 2021 at 12:01
Federico TraimanFederico Traiman
1,1411 gold badge13 silver badges18 bronze badges
Thanks for the help so far, turns out the fix was to compile HUD.java first (right click on the file-> Compile HUD.java). After compiling the java file the rest of the project could be compiled without any problems.
I don’t really know why this fixed it, or why IntelliJ wouldn’t do this automatically, but root error seems it has to do with IntelliJ not correctly handling having multiple classes in a single .java file.
answered Aug 26, 2012 at 18:09
joejoe
2,1092 gold badges15 silver badges13 bronze badges
2
This happened to me when I deleted a folder and then copy-pasted it back to the project.
Right-click project folder -> Rebuild
worked for me.
answered Aug 9, 2019 at 8:25
Tomas LukacTomas Lukac
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I had to right-click the project, and select «Reimport» under the «Run Maven» submenu.
answered Sep 19, 2018 at 19:58
bitsmcgee77bitsmcgee77
3813 silver badges10 bronze badges
I use maven in my project. For some reason IntelliJ was giving me these kind of wierd errors. I ran mvn clean and tried a resync and these errors disappeared.
answered Apr 25, 2013 at 19:58
Moiz RajaMoiz Raja
5,5926 gold badges39 silver badges52 bronze badges
1
recompiling the main Application.java class did it for me, right click on class > Recompile
answered Jan 20, 2019 at 6:28
Taranjit KangTaranjit Kang
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If you are using Lombok, make sure you have enabled annotation processing.
answered Feb 3, 2020 at 15:46
MuzammilMuzammil
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For me was a problem with Lombok, because it requires Annotation Processing to be enabled. You can find this checkbox on Settings > Build > Compiler > Annotation Processors
answered Feb 27, 2020 at 9:09
RaulDanielPopaRaulDanielPopa
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1
I know this is an old question, but as per my recent experience, this happens because the build resources are either deleted or Idea cannot recognize them as the source.
Wherever the error appears, provide sources for the folder/directory and this error must be resolved.
Sometimes even when we assign sources for the whole folder, individual classes might still be unavailable. For novice users simple solution is to import a fresh copy and build the application again to be good to go.
It is advisable to do a clean install after this.
answered Jul 14, 2014 at 15:41
MattMatt
1713 silver badges13 bronze badges
I know this thread is old but, another solution was to run
$ mvn clean install -Dmaven.test.skip=true
And on IntelliJ do CMD + Shift + A (mac os) -> type «Reimport all Maven projects».
If that doesn’t work, try forcing maven dependencies to be re-downloaded
$ mvn clean -U install -Dmaven.test.skip=true
answered Jul 19, 2019 at 13:23
edmaredmar
361 silver badge5 bronze badges
1
For me, the error was coming from @RequiredArgsConstructor(onConstructor = @__(@Inject))
, and the message was cannot find symbol __
. The error message right above this was «java: You aren’t using a compiler supported by lombok, so lombok will not work and has been disabled».
Adding argument below in VM options worked as suggested here worked for me.
-Djps.track.ap.dependencies=false
answered May 20, 2021 at 1:31
learnererlearnerer
3942 silver badges16 bronze badges
For my case, the issue was with using Lombok’s experimental feature @UtilityClass in my java project in Intellij Idea, to annotate a class methods as «static». When I explicitly made each method of the class as «static» instead of using the annotation, all the compilation issues disappeared.
answered Oct 2, 2018 at 20:20
RamRam
1911 gold badge2 silver badges12 bronze badges
Since this is the first hit on Google searching for «intelliJ cannot find symbol» error, I’m gonna throw in my solution as well.
The problem for me was that my project originated from Eclipse, and some files contained dependency on classes that were generated in src/generated-sources
by specifications in pom.xml. For some reason, this was not properly executed when I first opened the project and rebuilding/re-importing did not help, so the files were never generated.
The solution was to right-click on the module, and select Maven -> Generate Sources and Update Folders
That solved the issue and I could compile.
answered May 30, 2016 at 9:10
Make sure the source file of the java class you are trying to refer to has a .java
extension. It was .aj
in my case (I must have hit «Create aspect» instead of «Create class» when creating it). IntelliJ shows the same icon for this file as for «normal» class, but compiler does not see it when building.
Changing .aj
to .java
fixed it in my case.
answered Jun 14, 2016 at 21:23
fraczfracz
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Sometimes the class you want is in the test
source directory. Happened to me, anyway…
answered Feb 7, 2017 at 1:15
Sam BarnumSam Barnum
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I was having the same problem except that I was importing the classes for which dependencies were not resolving somehow. I refreshed maven projects, Rebuild Project. It still did not resolve.
Looks like IntelliJ was caching something incorrectly.
I restarted IntelliJ and that resolved the dependencies. I guess it cleared the cache somehow.
answered Aug 20, 2018 at 13:52
I’m seeing a lot of answers proposing a build or a re-build but just in case this don’t fix your problem just notice that IDEA can detect a method but it will not compile in case you have a new
before as it will be expecting the instance.
answered Feb 13, 2020 at 14:19
In my case, I had a problem with finding a class from another module. In pom.xml
, I just had this dependency with <scope>compile</scope>
specified. Removing this line helped.
answered Mar 24, 2020 at 14:52
nikiforovpizzanikiforovpizza
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1
This works for me, say class A depends on class B(and class c, d etc) but the error throws on class A which does not have any errors. So I try to compile class A alone first ->it shows error on the package of class B. So tried to compile whole package of class B. Now it throws which is the exact error class(on my case class B had error). Usually Intellj shows the exact error class with line number when compile/build. On some occasions it throws error in wrong place/class. Have a try.
answered Jan 23, 2021 at 13:43
Once when Maven Reimport, Rebuild Project, Invalidate caches didn’t help I deleted subfolders artifacts
and libraries
from .idea folder, not whole one, so I saved custom project settings.
…and when nothing written here helps check idea.log file as posted here
answered Mar 4, 2021 at 18:04
I tried everything and nothing worked for me. So, after wasting a couple of hours, I decided to upgrade the IntelliJ idea version, and finally, it worked!
answered Aug 5, 2021 at 10:20
AConsumerAConsumer
2,4112 gold badges24 silver badges33 bronze badges
Delete all the contents inside ~/.m2
. Start intellij-idea
.
(Using IntelliJ IDEA 2021.3 (Community Edition))
answered Mar 15, 2022 at 16:49
dr0idr0i
2,3402 gold badges18 silver badges36 bronze badges
In my case,
- close intelliJ.
- delete «.idea» (which are hidden folders by default) from project root.
- open IntelliJ
- open settings —> find annotation processors —> check «Enable annotation processing»
- Open Project structure from «File» menu. Set the appropriate JDK version.
answered Apr 2 at 0:37
coverboycoverboy
511 silver badge10 bronze badges
Introduction to Symbol Tables
Symbol tables are an important data structure created and maintained by compilers to store information associated with identifiers [1] in a given source code. This information is entered into the symbol tables during lexical and syntax analysis and is used in the later phases of compilation. As the declarations of classes, interfaces, variables, and methods are processed, their identifiers are bound to corresponding entries in the symbol tables. When uses of these identifiers are encountered in the source code, the compiler looks them up in the symbol tables and relies on this information for things such as verifying that a variable has been declared, determining the scope of a variable, and verifying that an expression is semantically correct with type checking. Symbol tables are also used for code generation and optimization [2].
A simplified representation of a symbol table entry (or simply, a symbol) in Java has the following format: <symbol name (identifier), type, scope, [attributes]>
. Given a global variable declaration like final double ratio;
the corresponding symbol would then be <ratio, double, global, [final]>
.
Install the Java SDK to identify and fix exceptions
Cannot Find Symbol Error
As its name implies, the cannot find symbol
error refers to a symbol which cannot be found. While there are multiple ways and reasons this can occur, they all boil down to the fact that the Java compiler is unable to find the symbol associated with a given identifier.
The message produced by the compiler for the cannot find symbol
error includes two additional fields:
- “symbol”—the name and type of the referenced identifier; and
- “location”—the specific class in which the identifier has been referenced.
What Causes the Cannot Find Symbol Error
The most common triggers for the cannot find symbol
compile-time error include:
- missing variable and method declarations;
- out-of-scope references to variables and methods;
- misspelled identifiers; and
- omitted import statements.
Cannot Find Symbol vs Symbol Not Found vs Cannot Resolve Symbol
As different Java compilers use slightly different terminology, the cannot find symbol
error can also be found under the terms symbol not found
and cannot resolve symbol
. Besides the naming, there is no difference between what these terms stand for.
Cannot Find Symbol Error Examples
Undeclared variable
When the Java compiler encounters a use of an identifier which it cannot find in the symbol table, it raises the cannot find symbol
error. Consequently, the most common occurrence of this error is when there is a reference to an undeclared variable. Unlike some other languages that don’t require explicit declaration of variables [3], or may allow declaring a variable after it has been referenced (via hoisting [4]), Java requires declaring a variable before it can be used or referenced in any way.
Fig. 1(a) shows how an undeclared variable, in this case the identifier average
on line 9, results in two instances of the cannot find symbol
error, at the positions where they appear in the code. Declaring this variable by specifying its data type (or, alternatively, inferring its type with the var
keyword in Java 10+) resolves the issue (Fig. 1(b)).
(a)
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2
3
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5
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7
8
9
10
11
12
package rollbar;
public class UndeclaredVariable {
public static void main(String... args) {
int x = 6;
int y = 10;
int z = 32;
average = (x + y + z) / 3.0; // average is not declared
System.out.println(average);
}
}
UndeclaredVariable.java:9: error: cannot find symbol
average = (x + y + z) / 3.0;
^
symbol: variable average
location: class UndeclaredVariable
UndeclaredVariable.java:10: error: cannot find symbol
System.out.println(average);
^
symbol: variable average
location: class UndeclaredVariable
2 errors
(b)
1
2
3
4
5
6
7
8
9
10
11
12
package rollbar;
public class UndeclaredVariable {
public static void main(String... args) {
int x = 6;
int y = 10;
int z = 32;
double average = (x + y + z) / 3.0;
System.out.println(average);
}
}
16.0
Out of scope variable
When a Java program tries to access a variable declared in a different (non-inherited or non-overlapping) scope, the compiler triggers the cannot find symbol
error. This is demonstrated by the attempt to access the variable counter
on lines 17 and 18 in Fig. 2(a), which is accessible only within the for
statement declared on line 11. Moving the counter
variable outside the for
loop fixes the issue, as shown on Fig. 2(b).
(a)
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package rollbar;
import java.util.Arrays;
import java.util.List;
public class OutOfScopeVariable {
public static void main(String... args) {
final List<String> strings = Arrays.asList("Hello", "World");
final String searchFor = "World";
for (int counter = 0; counter < strings.size(); counter++) {
if (strings.get(counter).equals(searchFor)) {
break;
}
}
if (counter < strings.size()) {
System.out.println("The word " + searchFor + " was found at index " + counter);
} else {
System.out.println("The word " + searchFor + " wasn't found");
}
}
}
OutOfScopeVariable.java:17: error: cannot find symbol
if (counter < strings.size()) {
^
symbol: variable counter
location: class OutOfScopeVariable
OutOfScopeVariable.java:18: error: cannot find symbol
System.out.println("The word " + searchFor + " was found at index " + counter);
^
symbol: variable counter
location: class OutOfScopeVariable
2 errors
(b)
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package rollbar;
import java.util.Arrays;
import java.util.List;
public class OutOfScopeVariable {
public static void main(String... args) {
final List<String> strings = Arrays.asList("Hello", "World");
final String searchFor = "World";
int counter;
for (counter = 0; counter < strings.size(); counter++) {
if (strings.get(counter).equals(searchFor)) {
break;
}
}
if (counter < strings.size()) {
System.out.println("The word " + searchFor + " was found at index " + counter);
} else {
System.out.println("The word " + searchFor + " wasn't found");
}
}
}
The word ‘World’ was found at index 1
Misspelled method name
Misspelling an existing method, or any valid identifier, causes a cannot find symbol
error. Java identifiers are case-sensitive, so any variation of an existing variable, method, class, interface, or package name will result in this error, as demonstrated in Fig. 3.
(a)
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10
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12
13
14
package rollbar;
public class MisspelledMethodName {
static int fibonacci(int n) {
if (n == 0) return 0;
if (n == 1) return 1;
return fibonacci(n - 1) + fibonacci(n - 2);
}
public static void main(String... args) {
int fib20 = Fibonacci(20); // Fibonacci ≠ fibonacci
System.out.println(fib20);
}
}
MisspelledMethodName.java:11: error: cannot find symbol
int fib20 = Fibonacci(20);
^
symbol: method Fibonacci(int)
location: class MisspelledMethodName
(b)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
package rollbar;
public class MisspelledMethodName {
static int fibonacci(int n) {
if (n == 0) return 0;
if (n == 1) return 1;
return fibonacci(n - 1) + fibonacci(n - 2);
}
public static void main(String... args) {
int fib20 = fibonacci(20);
System.out.println(fib20);
}
}
6765
Missing import statement
Using classes, either from the Java platform or any library, requires importing them correctly with the import
statement. Failing to do so will result in the cannot find symbol
error being raised by the Java compiler. The code snippet in Fig. 4(a) makes use of the java.util.List
class without declaring the corresponding import, therefore the cannot find symbol
error occurs. Adding the missing import
statement (line 4 in Fig. 4(b)) solves the problem.
(a)
package rollbar;
import java.util.Arrays;
public class MissingImportList {
private static final List<String> CONSTANTS = Arrays.asList("A", "B", "C");
public static void main(String... args) {
System.out.println(CONSTANTS);
}
}
MissingImportList.java:6: error: cannot find symbol
private static final List<String> CONSTANTS = Arrays.asList("A", "B", "C");
^
symbol: class List
location: class MissingImportList
(b)
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package rollbar;
import java.util.Arrays;
import java.util.List;
public class MissingImportList {
private static final List<String> CONSTANTS = Arrays.asList("A", "B", "C");
public static void main(String... args) {
System.out.println(CONSTANTS);
}
}
[A, B, C]
Less common examples
The root cause for the cannot find symbol
Java error can occasionally be found in some unexpected or obscure places. Such is the case with accidental semicolons that terminate a statement ahead of time (Fig. 5), or when object creation is attempted without a proper constructor invocation which has to have the new
keyword (Fig. 6).
(a)
package rollbar;
public class LoopScope {
public static void main(String... args) {
int start = 1, end = 10;
for (int i = start; i <= end; i++); {
System.out.print(i == end ? i : i + ", ");
}
}
}
LoopScope.java:7: error: cannot find symbol
System.out.print(i == end ? i : i + ", ");
^
symbol: variable i
location: class LoopScope
LoopScope.java:7: error: cannot find symbol
System.out.print(i == end ? i : i + ", ");
^
symbol: variable i
location: class LoopScope
LoopScope.java:7: error: cannot find symbol
System.out.print(i == end ? i : i + ", ");
^
symbol: variable i
location: class LoopScope
3 errors
(b)
package rollbar;
public class LoopScope {
public static void main(String... args) {
int start = 1, end = 10;
for (int i = start; i <= end; i++) {
System.out.print(i == end ? i : i + ", ");
}
}
}
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
(a)
package rollbar;
public class ObjectCreation {
public static void main(String... args) {
String s = String("Hello World!");
System.out.println(s);
}
}
ObjectCreation.java:5: error: cannot find symbol
String s = String("Hello World!");
^
symbol: method String(String)
location: class ObjectCreation
(b)
package rollbar;
public class ObjectCreation {
public static void main(String... args) {
String s = new String("Hello World!");
System.out.println(s);
}
}
Hello World!
Other causes for the cannot find symbol
error may include:
- using dependencies with old or incompatible versions;
- forgetting to recompile a program;
- building a project with an older JDK version;
- redefining platform or library classes with the same name;
- the use of homoglyphs in identifier construction that are difficult to tell apart;
- etc.
Conclusion
The cannot find symbol
error, also found under the names of symbol not found
and cannot resolve symbol
, is a Java compile-time error which emerges whenever there is an identifier in the source code which the compiler is unable to work out what it refers to. As with any other compilation error, it is crucial to understand what causes this error, pinpoint the issue and address it properly. In the majority of cases, referencing undeclared variables and methods, including by way of misspelling them or failing to import their corresponding package, is what triggers this error. Once discovered, resolution is pretty straightforward, as demonstrated in this article.
Track, Analyze and Manage Errors With Rollbar
Managing errors and exceptions in your code is challenging. It can make deploying production code an unnerving experience. Being able to track, analyze, and manage errors in real-time can help you to proceed with more confidence. Rollbar automates error monitoring and triaging, making fixing Java errors easier than ever. Sign Up Today!
References
[1] Rollbar, 2021. Handling the <Identifier> Expected Error in Java. Rollbar Editorial Team. [Online]. Available: https://rollbar.com/blog/how-to-handle-the-identifier-expected-error-in-java/. [Accessed Nov. 22, 2021].
[2] ITL Education Solutions Limited, Principles of Compiler Design (Express Learning), 1st ed. New Delhi: Pearson Education (India), 2012.
[3] Tutorialspoint.com, 2021. Python — Variable Types. [Online]. Available: https://www.tutorialspoint.com/python/python_variable_types.htm. [Accessed: Nov. 23, 2021].
[4] JavaScript Tutorial, 2021. JavaScript Hoisting Explained By Examples. [Online]. Available: https://www.javascripttutorial.net/javascript-hoisting/. [Accessed: Nov. 23, 2021]
The Cannot Find Symbol Error in Java error occurs when the Java compiler cannot find a symbol that you are trying to reference in your code. In this article, we will explore how to resolve the “Cannot Find Symbol” error in Java.
The “Cannot Find Symbol” error occurs when you are trying to reference a symbol that has not been defined or imported properly. Symbols can include variables, methods, and classes or in easy language when you try to reference an undeclared variable in your code. The error typically occurs when you have made a typo, used the wrong case in the symbol name, or when you are trying to reference a symbol that is out of scope. You may also encounter this error when you are using multiple files, and the compiler cannot find a class or package that you are trying to reference.
Common mistakes that lead to “Cannot Find Symbol” error in Java and resolving them, you can follow these steps:
- Typos
- Undeclared Variable
- Scope of Current block
- Import Statement
Typos
Make sure that the symbol you are trying to reference is spelled correctly and matches the case used in the definition.
Example 1:
Java
public
class
Main {
static
int
Large(
int
a,
int
b)
{
if
(a > b) {
return
a;
}
else
if
(b > a) {
return
b;
}
else
{
return
-
1
;
}
}
public
static
void
main(String... args)
{
int
value = large(
20
,
4
);
System.out.println(value);
}
}
Output:
./Main.java:17: error: cannot find symbol int value = large(20, 4); ^ symbol: method large(int,int) location: class Main
Explanation of the above program
We get this error as the function we initialized is Large(int a,int b) whereas we are calling large(a,b) so to resolve this typo mistake we just change large to Large.
Example 2:
Java
public
class
Main {
static
int
Large(
int
a,
int
b)
{
if
(a > b) {
return
a;
}
else
if
(b > a) {
return
b;
}
else
{
return
-
1
;
}
}
public
static
void
main(String... args)
{
int
value = Large(
20
,
4
);
System.out.println(value);
}
}
Undeclared Variable
We can also get errors by undeclared Variables.
Example 1:
Java
public
class
Main {
public
static
void
main(String[] args)
{
int
n1 =
500
;
int
n2 =
400
;
sum = n1 + n2;
System.out.println(sum);
}
}
Output:
./Main.java:6: error: cannot find symbol sum = n1 + n2; ^ symbol: variable sum location: class Main ./Main.java:7: error: cannot find symbol System.out.println(sum); ^ symbol: variable sum location: class Main
Explanation of the program
In the above example, the “Cannot find symbol” error occurs as we have not declared the sum. The corrected code is given below (will occur because “sum” is not declared. In order to solve the error, we need to define “int sum = n1+n2” before using the variable sum.
Example 2:
Java
public
class
Main {
public
static
void
main(String[] args)
{
int
n1 =
500
;
int
n2 =
400
;
int
sum = n1 + n2;
System.out.println(sum);
}
}
Check the scope
Make sure that the symbol you are trying to reference is within the scope of the current code block.
Example 1:
Java
public
class
Main {
public
static
void
main(String[] args)
{
int
x =
5
;
if
(x >
0
) {
int
y =
10
;
}
System.out.println(y);
}
}
Output:
./Main.java:8: error: cannot find symbol System.out.println(y); ^ symbol: variable y location: class Main
Explanation of the above program
In this program, we define an integer variable x and initialize it to 5. We then have an if statement that checks if x is greater than 0. If it is, we define another integer variable y, and initialize it to 10. However, y is only within the scope of the if block, and cannot be accessed outside of it.
Example 2:
Java
public
class
Main {
public
static
void
main(String[] args) {
int
x =
5
;
int
y =
0
;
if
(x >
0
) {
y =
10
;
}
System.out.println(y);
}
}
Check the import statements
Make sure that any classes or packages that you are trying to reference are imported properly.
Example 1:
Java
import
java.util.Rand;
public
class
Main {
public
static
void
main(String[] args)
{
Rand rand =
new
Rand();
int
x = rand.nextInt(
10
);
System.out.println(
"Random number: "
+ x);
}
}
Output:
./Main.java:1: error: cannot find symbol import java.util.Rand; ^ symbol: class Rand location: package java.util ./Main.java:6: error: cannot find symbol Rand rand = new Rand(); ^ symbol: class Rand location: class Main ./Main.java:6: error: cannot find symbol Rand rand = new Rand(); ^ symbol: class Rand location: class Main
Example 2:
Java
import
java.util.Random;
public
class
Main {
public
static
void
main(String[] args) {
Random rand =
new
Random();
int
x = rand.nextInt(
10
);
System.out.println(
"Random number: "
+ x);
}
}
Last Updated :
14 May, 2023
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Symbols and Symbol Table
Before diving into the details of the “cannot find a symbol” error, here is a brief introduction to symbols and symbol tables in Java. A symbol refers to an identifier in the compilation process in Java. All the identifiers used in the source code are collected into a symbol table in the lexical analysis stage. The symbol table is a very significant data structure created and maintained by the compilers to store all the identifiers and their information.
This information is entered into the symbol tables during lexical and syntax analysis which is then used in multiple phases of compilation.
From classes, variables, interfaces to methods, all of them require an identifier for declaration. During the code generation process, when these identifiers are encountered in the source code, the compiler checks for them in the symbol tables and the stored information is then used to verify the declarations, the scope of a variable, and verifying that the expression is semantically correct or not.
The compilation process usually does not go as smooth as you would think. Errors are inevitable in any development stage and one of the very commonly occurring errors during the compilation process is Java “cannot Find Symbol” Error. In this article, we will be discussing the reasons behind the occurrence of Java cannot find symbol errors and how you can resolve them.
As the name suggests, the Java cannot find symbol error occurs when a required symbol cannot be found in the symbol table. Although there can be various reasons behind this, it points to one fact the Java compiler was unable to find the symbol and its details associated with a given identifier.
As there are a variety of Java compilers available, many of them use slightly different terminologies, because of that, you can also find the “cannot find symbol” error termed as the “symbol not found” or “cannot resolve symbol” error. Besides the name, there is simply no difference between these errors.
Structure of Java Cannot Find Symbol Error
The compiler output a specific error message with the cannot find symbol error.
It contains the following two fields that indicate the missing symbol and its location:
- Symbol: The name and type of the identifier you are looking for.
- Location: The particular class in which that identifier has been referenced.
Causes of Java Cannot Find Symbol Error
We will be discussing the following most common causes of the cannot find symbol error during compilation,
- misspelt identifiers
- Undeclared variables
- Out of scope references to variables and methods
- The unintentional omission of import statements
Misspelt identifier names
This is the most common and most occurring reason behind the Java cannot find symbol error. Misspelling an existing variable, class, interface, package name or a method causes the “cannot find symbol error” as the compiler cannot recognize the symbol and identifies it as an undeclared variable. Java identifiers are also case-sensitive, so even a slight variation of an existing variable will result in this error.
See code example below:
1. public class MisspelledMethodNameExample { 2. static int findLarger(int n1, int n2) { 3. if (n1 > n2) return n1; 4. if (n2 > n11) return n2; 5. if (n2 == n11) return -1; 6. } 7. 8. public static void main(String... args) { 9. int value = findlarger(20, 4); // findlarger ≠ findLarger 10. System.out.println(value); 11. } 12. }
MisspelledMethodNameExample.java:9: error: cannot find symbol int value = Fibonacci(20); ^ symbol: method findLarger(int, int) location: class MisspelledMethodNameExample
It can be easily resolved by correcting the spelling of the function in line 9.
Undeclared variables
When the Java compiler come across an identifier used in the code but it cannot be found in the symbol table, the “cannot find symbol” error is shown. The only reason behind the absence of a variable from the symbol table is that it is not declared in the code. Some new programming languages do not require explicit declaration of variables but it is mandatory in Java to always declare a variable before it is used or referenced in the source code.
The code snippet below demonstrates an undeclared variable in the code. In this case, the identifier sum on line 7, causes the Java “cannot find symbol error”.
See code example below:
1. public class UndeclaredVariableExample 2. { 3. public static void main(String... args) { 4. int num1 = 5; 5. int num2 = 10; 6. int num3 = 43; 7. sum = (num1 + num2 + num3) // sum is not declared 8. System.out.println(sum); 9. } 10. }
UndeclaredVariableExample.java:7: error: cannot find symbol sum = (num1 + num2 + num3); ^ symbol: variable sum location: class UndeclaredVariableExample UndeclaredVariableExample.java:8: error: cannot find symbol System.out.println(sum); ^ symbol: variable sum location: class UndeclaredVariableExample 2 errors
Declaring this variable by specifying the appropriate data type can easily resolve the error.
See this corrected code below,
1. public class UndeclaredVariableExample 2. { 3. public static void main(String args) { 4. int num1 = 5; 5. int num2 = 10; 6. int num3 = 43; 7. 8. int sum = (num1 + num2 + num3); 9. System.out.println(sum); 10. } 11. }
Out of scope variable
When a Java code attempts to access a variable declared out of scope such as in a non-inherited scope the compiler will result in issuing the “cannot find symbol” error. This commonly happens when you attempt to access a variable declared inside a method or a loop, from outside of the method.
See this code example below where the “cannot find symbol” error has occurred when the counter variable which is declared inside a for loop is attempted to be accessed from out of the loop.
See code below:
1. public class OutOfScopeExample 2. { 3. public static void main(String args) { 4. 5. for (int counter = 0; counter < 100; counter++) 6. { … } 7. 8. System.out.println(“Even numbers from 0 to 100”) 9. if (counter mod 2 == 0) 10. { 11. System.out.println(counter); 12. } 13. } 14. }
OutOfScopeVariableExample.java:9: error: cannot find symbol if (counter mod 2 == 0) ^ symbol: variable counter location: class OutOfScopeVariableExample OutOfScopeVariableExample.java:12: error: cannot find symbol System.out.println(counter); ^ symbol: variable counter location: class OutOfScopeVariableExample 2 errors
I can be easily resolved by just moving the if block inside the for loop (local scope).
See this code example,
1. public class OutOfScopeExample 2. { 3. public static void main(String... args) { 4. 5. for (int counter = 0; counter < 100; counter++) 6. { 7. System.out.println(“Even numbers from 0 to 100”) 8. if (counter mod 2 == 0) 9. { 10. System.out.println(counter); 11. } 12. } 13. } 14. }
Missing import statement
Java allows you to use built-in classes or any imported libraries in your code to save your time by reusing the code but it requires importing them properly using the import statements at the start. Missing the import statement in your code will result in the cannot find symbol error.
java.util.Math class is utilized in the code given below but it is not declared with the “import” keyword, resulting in the “cannot find symbol error”.
See code below:
1. public class MissingImportExample { 2. 3. public static void main(String args) 4. { 5. double sqrt19 = Math.sqrt(19); 6. System.out.println("sqrt19 = " + sqrt19); 7. } 8. }
MissingImportExample.java:6: error: cannot find symbol double sqrt19 = Math.sqrt(19); ^ symbol: class Math location: class MissingImportExample
Adding the missing import statement can easily solve the issue, see code below:
1. import java.util.Math; 2. 3. public class MissingImporExample { 4. 5. public static void main(String args) 6. { 7. double sqrt19 = Math.sqrt(19); 8. System.out.println("sqrt19 = " + sqrt19); 9. } 10. }
Miscellaneous reasons
We have covered some of the main causes of the “cannot find symbol” Java error but occasionally it can also result due to some unexpected reasons. One such case is when attempting to create an object without the new keyword or an accidental semicolon at the wrong place that would terminate the statement at an unexpected point.
Also Read: Functional Interfaces In Java
Some other causes for the cannot find symbol error may include when you forget to recompile the code or you end up using the dependencies with an incompatible version of Java. Building a project with a very old JDK version can also be a reason as well as mistakenly redefining platform or library classes with the same identifier.
Conclusion
We have discussed that the “cannot find symbol Java” error is a Java compile-time error which is encountered whenever an identifier in the source code is not identified by the compiler. Similar to any other compilation error, it is very significant to understand the causes of this error, so that you can easily pinpoint the issue and address it properly.
Once you can discover the reason behind the error, it can be easily resolved as demonstrated by various examples in this article.
What is the Cannot Find Symbol Java Error?
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The Cannot Find Symbol in Java is a compilation error that occurs when we try to refer to something that is not present in the Java Symbol Table. A very common example of this error is using a variable that is not declared in the program.
Java compilers create and maintain Symbol tables. The symbol table stores the information of the identifiers i.e. classes, interfaces, variables, and methods in the given source of code. When we use these identifiers in our code, the compiler looks up to the symbol table for information. If the identifier is not declared or is not present in the given scope the compiler throws ‘Cannot Find Symbol’.
What Causes the Java Cannot Find Symbol Error?
There are multiple ways and reasons this error can occur, they all boil down to the fact that the online Java compiler couldn’t find the identifier in the Symbol table. Some of the very commonly made mistakes are listed below:
- Java is case sensitive, thus hello and Hello are two different variables.
- If identifiers are misspelled say the variable’s name is name and we are trying to access nmae can cause an error.
- Sometimes variables are declared in a particular iterating loop or method and if we try to call them from outside causes an error as it is out of the scope of the variable.
- Using variables without their declaration is also the common cause of the Java ‘Cannot find Symbol’ error.
- Sometimes we use methods from classes of a different package. To do so we are required to import the package of the class. Missing import statements can cause the error too.
- Use of underscore, dollar sign, numbers, letter even a character before or after different from the initial declaration can cause ‘Cannot Find Symbol’.
Examples of Java Cannot Find Symbol error
Let us now see these common errors in the form of code:
Example 1
Let us take a very simple example of a function that takes user input of a number and returns if the number is even or odd.
Output:
In the example above, the Scanner class is not imported and thus it is throwing a Cannot Find Symbol error. The compiler is not able to find Scanner in the program. Once we import the package, it is able to identify the Scanner class.
Example 2
Another example is wrong spelling and undeclared variables. Let us take a simple example where we multiply a variable a few times in a loop.
Output:
In the example above we can see 3 errors, all of them being ‘cannot find symbol’. The first one is because N is not declared in the program, and the two are because we declared finalResult but we are calling final_Result. Thus, a single underscore can also cause an error.
Example 3
Lastly, out-of-scope variables also cause a ‘Cannot find Symbol’ error, below example demonstrates it.
Output:
In the example above, the sum variable is declared inside the for loop and its scope is only inside for loop. As we are trying to access it outside the for loop, it is causing the error.
Structure of Java Cannot Find Symbol
Look at the output generated by the compiler for the 3rd example:
As we can see in the output, the compiler tells the line number of the error as well as points to the variable where the error occurred and the type of the error which is cannot find symbol in this case.
The compiler also produces the cannot find symbol including these two additional fields:
- The very first one is the symbol it is unable to find, i.e. the name and type of the referenced identifier.
- The other field is the location of the place where the symbol is used. The class and line number are returned where the identifier has been referenced.
Cannot Find Symbol vs Symbol Not Found vs Cannot Resolve Symbol
Different compilers may use slightly different terminologies. The ‘Cannot Find Symbol’, ‘Symbol Not Found’, and ‘Cannot Resolve Symbol’ are all same errors only. Besides the naming, these convey the same meaning to the user and the compiler.
Learn more about Java errors
Conclusion
- The ‘Cannot Find Symbol’ error in Java is a compilation error caused when the compiler cannot find a reference to an identifier.
- Silly mistakes like case sensitivity, use of underscore, use of undeclared variables, use of out-of-scope variables, etc. can cause this error.
- It is also identified by ‘Symbol Not Found’ and ‘Cannot Resolve Symbol’.