Lỗi class does not have a main method năm 2024

The Java

public static void main(String[] args){
  // some code
}

7 method is usually the first method you learn about when you start programming in Java because its the entry point for executing a Java program. The

public static void main(String[] args){
  // some code
}

7 method can contain code to execute or call other methods, and it can be placed in any class that’s part of a program. More complex programs usually have a class that contains only the

public static void main(String[] args){
  // some code
}

7 method. The class that contains the

public static void main(String[] args){
  // some code
}

7 method can have any name, although typically you can just call the class

public class Test {
  static void main(String[] args){
    System.out.println("Hello, World!");
  }
}

1.

In the examples that follow, the class that contains the

public static void main(String[] args){
  // some code
}

7 method is called

public class Test {
  static void main(String[] args){
    System.out.println("Hello, World!");
  }
}

3:

Test.java

public class Test {
  public static void main(String[] args){
    System.out.println("Hello, World!");
  }
}

In this article you’ll learn what each component of the

public static void main(String[] args){
  // some code
}

7 method means.

The syntax of the

public static void main(String[] args){
  // some code
}

7 method is always:

public static void main(String[] args){
  // some code
}

You can change only the name of the

public class Test {
  static void main(String[] args){
    System.out.println("Hello, World!");
  }
}

6 array argument. For example, you can change

public class Test {
  static void main(String[] args){
    System.out.println("Hello, World!");
  }
}

7 to

public class Test {
  static void main(String[] args){
    System.out.println("Hello, World!");
  }
}

8. The

public class Test {
  static void main(String[] args){
    System.out.println("Hello, World!");
  }
}

6 array argument can be written as

javac Test.java
java Test

0 or

javac Test.java
java Test

1.

The access modifier of the

public static void main(String[] args){
  // some code
}

7 method needs to be

javac Test.java
java Test

2 so that the JRE can access and execute this method. If a method isn’t public, then access is restricted. In the following example code, the

public static void main(String[] args){
  // some code
}

7 method is missing the

javac Test.java
java Test

2 access modifier:

Test.java

public class Test {
  static void main(String[] args){
    System.out.println("Hello, World!");
  }
}

When you compile and run the program, the following error occurs because the

public static void main(String[] args){
  // some code
}

7 method isn’t public and the JRE can’t find it:

javac Test.java
java Test

Output

Error: Main method not found in class Test, please define the `main` method as:
   public static void main(String[] args)
or a JavaFX application class must extend javafx.application.Application

When the Java program starts, there is no object of the class present. The

public static void main(String[] args){
  // some code
}

7 method has to be

javac Test.java
java Test

8 so that the JVM can load the class into memory and call the

public static void main(String[] args){
  // some code
}

7 method without creating an instance of the class first. In the following example code, the

public static void main(String[] args){
  // some code
}

7 method is missing the

javac Test.java
java Test

8 modifier:

Test.java

public class Test {
  public void main(String[] args){
    System.out.println("Hello, World!");
  }
}

When you compile and run the program, the following error occurs because the

public static void main(String[] args){
  // some code
}

7 method isn’t

javac Test.java
java Test

8:

javac Test.java
java Test

Output

Error: Main method is not static in class Test, please define the `main` method as:
   public static void main(String[] args)

Every Java method must provide the return type. The Java

public static void main(String[] args){
  // some code
}

7 method return type is

Output

Error: Main method not found in class Test, please define the `main` method as:
   public static void main(String[] args)
or a JavaFX application class must extend javafx.application.Application

6 because it doesn’t return anything. When the

public static void main(String[] args){
  // some code
}

7 method is finished executing, the Java program terminates, so there is no need for a returned object. In the following example code, the

public static void main(String[] args){
  // some code
}

7 method attempts to return something when the return type is

Output

Error: Main method not found in class Test, please define the `main` method as:
   public static void main(String[] args)
or a JavaFX application class must extend javafx.application.Application

6:

Test.java

public class Test {
  public static void main(String[] args){
    return 0;
  }
}

When you compile the program, the following error occurs because Java doesn’t expect a return value when the return type is

Output

Error: Main method not found in class Test, please define the `main` method as:
   public static void main(String[] args)
or a JavaFX application class must extend javafx.application.Application

6:

javac Test.java

public static void main(String[] args){
  // some code
}

0

The Java

public static void main(String[] args){
  // some code
}

7 method is always named

public static void main(String[] args){
  // some code
}

7. When a Java program starts, it always looks for the

public static void main(String[] args){
  // some code
}

7 method. The following example code shows a

public static void main(String[] args){
  // some code
}

7 method renamed to

public class Test {
  public void main(String[] args){
    System.out.println("Hello, World!");
  }
}

8:

Test.java

public static void main(String[] args){
  // some code
}

1

When you compile and run the program, the following error occurs because the JRE can’t find the

public static void main(String[] args){
  // some code
}

7 method in the class:

javac Test.java
java Test

Output

Error: Main method not found in class Test, please define the `main` method as:
   public static void main(String[] args)
or a JavaFX application class must extend javafx.application.Application

Java

public static void main(String[] args){
  // some code
}

7 method accepts a single argument of type

public class Test {
  static void main(String[] args){
    System.out.println("Hello, World!");
  }
}

6 array. Each string in the array is a command line argument. You can use command line arguments to affect the operation of the program, or to pass information to the program, at runtime. The following example code shows how to print the command line arguments that you enter when you run the program:

Test.java

public static void main(String[] args){
  // some code
}

4

When you compile the program and then run it with a few command line arguments separated by spaces, the arguments get printed in the terminal:

public static void main(String[] args){
  // some code
}

5

public static void main(String[] args){
  // some code
}

6

In this article you learned about each component of the Java

public static void main(String[] args){
  // some code
}

7 method. Continue your learning with more Java tutorials.