1. Обзор
В этом кратком руководстве мы поговорим об ошибке компилятора Java
«ожидается класс, интерфейс или перечисление» .
В основном с этой ошибкой сталкиваются разработчики, которые являются новичками в мире Java.
Давайте рассмотрим несколько примеров этой ошибки и обсудим, как их исправить.
2. Неуместные фигурные скобки
Основной причиной ошибки
«ожидается класс, интерфейс или перечисление»
, как правило, является неуместная фигурная скобка
_ «}»
_
. Это может быть дополнительная фигурная скобка после урока. Это также может быть метод, случайно написанный вне класса.
Давайте посмотрим на пример:
public class MyClass {
public static void main(String args[]) {
System.out.println("Baeldung");
}
}
}----/MyClass.java:6: error: class, interface, or enum expected
}
^
1 error
----В приведенном выше примере кода в последней строке есть дополнительная фигурная скобка __ «}», что приводит к ошибке компиляции. Если мы удалим его, код скомпилируется.
Давайте посмотрим на другой сценарий, где эта ошибка происходит:
public class MyClass {
public static void main(String args[]) {
//Implementation
}
}
public static void printHello() {
System.out.println("Hello");
}----/MyClass.java:6: error: class, interface, or enum expected
public static void printHello()
^/MyClass.java:8: error: class, interface, or enum expected
}
^
2 errors
----
В приведенном выше примере мы получим ошибку, потому что метод
printHello ()
находится вне класса
MyClass
. Мы можем исправить это, переместив закрывающие фигурные скобки
«}»
в конец файла. Другими словами, переместите метод
printHello ()
внутрь
MyClass
.
3. Заключение
В этом кратком руководстве мы обсудили ошибку компилятора Java «ожидаемый класс, интерфейс или перечисление» и продемонстрировали две вероятные основные причины.
I have been troubleshooting this program for hours, trying several configurations, and have had no luck. It has been written in java, and has 33 errors (lowered from 50 before)
Source Code:
/*This program is named derivativeQuiz.java, stored on a network drive I have permission to edit
The actual code starts below this line (with the first import statement) */
import java.util.Random;
import java.Math.*;
import javax.swing.JOptionPane;
public static void derivativeQuiz(String args[])
{
// a bunch of code
}
The error log (compiled in JCreator):
--------------------Configuration: <Default>--------------------
H:Derivative quizderivativeQuiz.java:4: class, interface, or enum expected
public static void derivativeQuiz(String args[])
^
H:Derivative quizderivativeQuiz.java:9: class, interface, or enum expected
int maxCoef = 15;
^
H:Derivative quizderivativeQuiz.java:10: class, interface, or enum expected
int question = Integer.parseInt(JOptionPane.showInputDialog(null, "Please enter the number of questions you wish to test on: "));
^
H:Derivative quizderivativeQuiz.java:11: class, interface, or enum expected
int numExp = Integer.parseInt(JOptionPane.showInputDialog(null, "Please enter the maximum exponent allowed (up to 5 supported):" ));
^
H:Derivative quizderivativeQuiz.java:12: class, interface, or enum expected
Random random = new Random();
^
H:Derivative quizderivativeQuiz.java:13: class, interface, or enum expected
int coeff;
^
H:Derivative quizderivativeQuiz.java:14: class, interface, or enum expected
String equation = "";
^
H:Derivative quizderivativeQuiz.java:15: class, interface, or enum expected
String deriv = "";
^
H:Derivative quizderivativeQuiz.java:16: class, interface, or enum expected
for(int z = 0; z <= question; z++)
^
H:Derivative quizderivativeQuiz.java:16: class, interface, or enum expected
for(int z = 0; z <= question; z++)
^
H:Derivative quizderivativeQuiz.java:16: class, interface, or enum expected
for(int z = 0; z <= question; z++)
^
H:Derivative quizderivativeQuiz.java:19: class, interface, or enum expected
deriv = "";
^
H:Derivative quizderivativeQuiz.java:20: class, interface, or enum expected
if(numExp >= 5)
^
H:Derivative quizderivativeQuiz.java:23: class, interface, or enum expected
equation = coeff + "X^5 + ";
^
H:Derivative quizderivativeQuiz.java:24: class, interface, or enum expected
deriv = coeff*5 + "X^4 + ";
^
H:Derivative quizderivativeQuiz.java:25: class, interface, or enum expected
}
^
H:Derivative quizderivativeQuiz.java:29: class, interface, or enum expected
equation = equation + coeff + "X^4 + ";
^
H:Derivative quizderivativeQuiz.java:30: class, interface, or enum expected
deriv = deriv + coeff*4 + "X^3 + ";
^
H:Derivative quizderivativeQuiz.java:31: class, interface, or enum expected
}
^
H:Derivative quizderivativeQuiz.java:35: class, interface, or enum expected
equation = equation + coeff + "X^3 + ";
^
H:Derivative quizderivativeQuiz.java:36: class, interface, or enum expected
deriv = deriv + coeff*3 + "X^2 + ";
^
H:Derivative quizderivativeQuiz.java:37: class, interface, or enum expected
}
^
H:Derivative quizderivativeQuiz.java:41: class, interface, or enum expected
equation = equation + coeff + "X^2 + ";
^
H:Derivative quizderivativeQuiz.java:42: class, interface, or enum expected
deriv = deriv + coeff*2 + "X + ";
^
H:Derivative quizderivativeQuiz.java:43: class, interface, or enum expected
}
^
H:Derivative quizderivativeQuiz.java:47: class, interface, or enum expected
equation = equation + coeff + "X + ";
^
H:Derivative quizderivativeQuiz.java:48: class, interface, or enum expected
deriv = deriv + coeff;
^
H:Derivative quizderivativeQuiz.java:49: class, interface, or enum expected
}
^
H:Derivative quizderivativeQuiz.java:53: class, interface, or enum expected
equation = equation + coeff;
^
H:Derivative quizderivativeQuiz.java:54: class, interface, or enum expected
if(deriv == "")
^
H:Derivative quizderivativeQuiz.java:57: class, interface, or enum expected
}
^
H:Derivative quizderivativeQuiz.java:114: class, interface, or enum expected
JOptionPane.showMessageDialog(null, "Question " + z + "\" + question + "nDerivative: " + deriv);
^
H:Derivative quizderivativeQuiz.java:115: class, interface, or enum expected
}
^
33 errors
Process completed.
I feel like this is a basic error, and yet I can’t seem to find it.
If it makes a difference, I am using JCreator to compile and everything is installed correctly.
UPDATE:
I have fixed the errors involved (Class declaration and incorrect import statements (someone went back and deleted a few semicolons))
Working code:
import java.util.Random;
import javax.swing.JOptionPane;
import java.lang.String;
public class derivativeQuiz_source{
public static void main(String args[])
{
//a bunch more code
}
}
Thanks for all the help
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In Java, the class interface or enum expected error is a compile-time error. There can be one of the following reasons we get “class, interface, or enum expected” error in Java:
Case 1: Extra curly Bracket
Java
class Hello {
public static void main(String[] args)
{
System.out.println("Helloworld");
}
}
}
In this case, the error can be removed by simply removing the extra bracket.
Java
class Hello {
public static void main(String[] args)
{
System.out.println("Helloworld");
}
}
Case 2: Function outside the class
Java
class Hello {
public static void main(String args[])
{
System.out.println("HI");
}
}
public static void func() { System.out.println("Hello"); }
In the earlier example, we get an error because the method func() is outside the Hello class. It can be removed by moving the closing curly braces “}” to the end of the file. In other words, move the func() method inside of Hello.
Java
class Hello {
public static void main(String args[])
{
System.out.println("HI");
}
public static void func()
{
System.out.println("Hello");
}
}
Case 3: Forgot to declare class at all
There might be a chance that we forgot to declare class at all. We will get this error. Check if you have declared class, interface, or enum in your java file or not.
Case 4: Declaring more than one package in the same file
Java
package A;
class A {
void fun1() { System.out.println("Hello"); }
}
package B;
public class B {
public static void main(String[] args)
{
System.out.println("HI");
}
}
We can not put different packages into the same source file. In the source file, the package statement should be the first line.
Java
package A;
class A {
void fun1() { System.out.println("Hello"); }
}
public class B {
public static void main(String[] args)
{
System.out.println("HI");
}
}
Last Updated :
28 Jan, 2021
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How to Fix Error: “Class, Interface, or Enum Expected” ?
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The braces in java are served as a scope limit. The beginning and end of a code block are indicated by curly brackets.
Curly brackets cause the compile-time error known as the class interface or enum expected error in Java. This issue typically happens when the program ends with an extra curly brace.
Since everything in Java is programmed inside a class, interface, or enum, if you close the curly bracket for one class and add another, the compiler will assume that another class is starting and will complain about the class, interface, or enum keyword, as illustrated in the following program:
Code explanation
If we compile this code it will raise this error
because of extra braces.
Misplaced Curly Braces
The root cause of the “class, interface, or enum expected” error is typically a misplaced curly brace “}”. This can be an extra curly brace after the class. It could also be a method accidentally written outside the class.
Code Explanation
The following error will be raised
To solve this error simply remove extra brace
Function Outside Class (Intro+ Add Code Example Ti Fix Error)
A method present outside of a class may also be the cause of this problem. The compilation process will fail since this method does not belong to any class. Moving the method within the class will fix this issue.
Code Explanation
In Above code method1 is outside of class classb this will raise error.To solve this placed method1 inside of classb.
Multiple Package
In a Java file, only one package can be declared. The expected compilation error for a class, interface, or enum will occur if we have more packages than necessary.
Code Explanation
To solve error import only one package.Each source file can only have one package statement, and it must apply to all of the file’s types.
Conclusion
- The class, interface, or enum expected error occurs due to a few different reasons.
- This error can occur due to misplaced braces by removing extra braces or adding missing braces this error can be solved.
- If a method is included outside of a class, then this error can happen. By placing method within class error can be solved.
- This error can be raised if multiple packages are imported in a java file. It is possible to fix errors by importing just one package.
- The solution to this problem is rather simple.
Introduction
Java errors are the lifelong enemy of every developer, be it a novice or an expert. A Java developer faces a plethora of different types of errors. One such error is the class interface or enum expected error.
In this article, we will be focusing on the reason behind the occurrences of this error and how to resolve it.
The class interface or enum expected error is a compile-time error in Java. It is mainly faced by the developers at their early stages in Java development.
The primary reason behind the class interface or enum expected error is the incorrect number of curly braces. Typically, this error is faced when there is an excess or shortage of a curly brace at the end of the code.
Since the whole code is placed inside a class, interface, or enum in Java, an extra curly brace makes the compiler understand that another class is starting and no closing braces after that is considered as the incompletion of class hence it will complain about class, interface, or enum keyword.
We will be now discussing some of the basic causes of class, interface, or enum expected error and how you can fix them.
1. Misplaced Curly Braces
The primary cause of the “class, interface or enum expected” error is typically a mistyped curly brace “}” in your code.
This error could have been encountered due to either an extra curly brace after the class or due to a missed curly brace in your code.
Look at this example below:
1. public class MyClass {
2. public static void main(String args[]) {
3. System.out.println("Hello World");
4. }
5. }
6. }
Error: /MyClass.java:6: error: class, interface, or enum expected } ^ 1 error
In the above code demonstration, there is an extra “}” curly brace at the last which is resulting in the compilation error. The removal of the extra “}” can easily resolve the error in this case.
2. A Function is declared outside of the class
Let’s look at another scenario where this error usually occurs:
1. public class MyClass {
2. public static void main(String args[]) {
3. //Implementation
4. }
5. }
6. public static void printMessage() {
7. System.out.println("Hello World");
8. }
Error: /MyClass.java:6: error: class, interface, or enum expected public static void printHello() ^ /MyClass.java:8: error: class, interface, or enum expected } ^ 2 errors
In the above example, the class, interface, or enum expected error is faced because the function printHello() is defined outside of the class.
Although, this error is also somewhat due to misplacing of curly braces but it is important to identify this different cause so that the user would also quickly look at all the methods and their placement in the code to make sure that all functions are properly placed.
This can be easily fixed by just moving the closing curly braces “}” to the end of the class so that the printHello() method will be now inside the MyClass.
3. Class is not declared
You would also face this error if you have not declared the class. There might be a chance that you forgot to declare the class at all.
Always make sure that the class, interface, or enum is properly declared in your java file.
4. Declaration of multiple packages in the same file
More than one package cannot be present in the same Java source file. It will result in the class interface or enum expected error if your source file contains more than one package.
See the code example below where two packages are present in the same code. You must avoid this in your code:
1. package p1;
2. class class1 {
3. void fun1() { System.out.println("Hello World"); }
4. }
5. package p2; //getting class interface or enum expected
6. public class class2 {
7. public static void main(String[] args)
8. {
9. System.out.println("Hello World");
10. }
Tips to prevent the “class, interface, or enum expected” error in Java
All the codes that we have discussed above consisted of very limited lines which makes it very easy for users to spot the misplaced curly brace but it will not be that simple if we have to look for it in a huge code with multiple methods and classes.
·Use a modern IDE
The use of an IDE can be a very good solution for preventing this error.
Various new and modern IDEs have features that automatically add the missing curly braces as detected or they right away highlights the extra added braces in your code before compilation.
Despite that, even if the error occurs, modern IDEs like Eclipse or Netbeans also give the user a visible sign of where the error is located and it will pinpoint the exact location of the error in your code.
·Indent your code
Assuming that you are not able to use an IDE, if you are writing your code in a word processing software such as Notepad, then try to correctly indent your code.
The clear indentations make it easier to identify if there are extra curly braces at the end of the code as they would be at the same indentation level, which should not be part of a valid code.
You can simply remove the extra curly braces for the code before compiling it and the class interface or enum expected error can be easily prevented.
Wrapping it up
We discussed various reasons behind the occurrence of class, interface, or enum expected error. We also looked into the same ways to prevent this error.
It is a very trivial error and can be very quickly solved but it can sometimes become a bit troubling especially when occurred in a big code. To cater to that, always use a modern IDE to prevent this error.
See Also: How To Iterate Over a Map In Java
