Question

我正在完成一项任务，这是我们第一次做方法。我试图创建下面的方法，但它一直说void不是一个有效的类型。问候它的名字是一个非法的修饰符，它说我在括号后需要一个分号。我不能为我的生活弄清楚我做错了什么，正如我在所有我看过的例子中所看到的那样。

public static void greeting(){
        String greet = "This program will play 3 games of rock paper scissors with you.\n\n"+
                          "It will ask you for your choice and then randomly generate a choice for the computer.\n\n"+
                          "After all 3 games you will be shown the total results.";
        JOptionPane.showMessageDialog(null, greet, "Greeting",1);

    }

这里是完整的代码：

import javax.swing.*;
import java.util.*;

public class RPS_Game {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        public static void greeting(){
            String greet = "This program will play 3 games of rock paper scissors with you.\n\n"+
                           "It will ask you for your choice and then randomly generate a choice for the computer.\n\n"+
                           "After all 3 games you will be shown the total results.";
            JOptionPane.showMessageDialog(null, greet, "Greeting",1);
        }
    }
}

好的我把它改成了它并且它有效。有点让我感到困惑，因为看起来我要使用的方法应该被编写，然后在下面调用。

import javax.swing.*;

public class RPS_Game {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        greeting();

    }

    public static void greeting(){
        String greet = "This program will play 3 games of rock paper scissors with you.\n\n"+
                       "It will ask you for your choice and then randomly generate a choice for the computer.\n\n"+
                       "After all 3 games you will be shown the total results.";
        JOptionPane.showMessageDialog(null, greet, "Greeting",1);

    }

}

Answer 1

你必须把所有东西放在一个类中，制作一个main方法，并从main方法调用你的方法，如下所示：

public class Greeting {

    public static void main(String[] args) {
        greeting();
    }

    public static void greeting(){
        String greet = "This program will play 3 games of rock paper scissors with you.\n\n"+
                      "It will ask you for your choice and then randomly generate a choice for the computer.\n\n"+
                      "After all 3 games you will be shown the total results.";
        JOptionPane.showMessageDialog(null, greet, "Greeting",1);
    }
}

Answer 2

我建议您将文件命名为RPSGame.java，因为Java约定使用CamelCase作为类名。

您不能将方法嵌套在其他方法中。

import javax.swing.*;
import java.util.*;

// Avoid using '_' (underscore) in the filename/classname because of conventions.
public class RPSGame {
    // Define greeting
    public static void greeting() {
        String greet = "This program will play 3 games of rock paper scissors with you.\n\n"+
                       "It will ask you for your choice and then randomly generate a choice for the computer.\n\n"+
                       "After all 3 games you will be shown the total results.";

        JOptionPane.showMessageDialog(null, greet, "Greeting",1);
    }

    // The main() method is the entry point into your class, call your methods here.
    public static void main(String[] args) {
        greeting(); // Call greeting.
    }
}

Answer 3

你需要把你的方法放在main方法之外，然后从main调用它：

import javax.swing.*;

public class RPS_Game {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        greeting();
    }

    public static void greeting() {
        String greet = "This program will play 3 games of rock paper scissors with you.\n\n" +
                "It will ask you for your choice and then randomly generate a choice for the computer.\n\n" +
                "After all 3 games you will be shown the total results.";
        JOptionPane.showMessageDialog(null, greet, "Greeting", 1);
    }
}

此外，您的代码中不需要import java.util.*;库。

Answer 4

您无法在方法内定义方法，只能在方法内调用方法。

import javax.swing.*;
import java.util.*;

public class RPS_Game {

    public static void greeting(){
        String greet = "This program will play 3 games of rock paper scissors with you.\n\n"+
                       "It will ask you for your choice and then randomly generate a choice for the computer.\n\n"+
                       "After all 3 games you will be shown the total results.";
        JOptionPane.showMessageDialog(null, greet, "Greeting",1);
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        greeting();

    }
}

Java方法定义

4 个答案: