Java 方法中的参数未编译

我只是想创建一个简短的java程序，向用户请求一个int，然后向该int添加3并显示它。由于某种原因，我把语法弄错了

import java.util.Scanner;

public class test {


    public int attempt (int b) {
            return 3+entry;
    }


    int r = attempt(entry);

    public static void main (String[] args){
            Scanner keyboard = new Scanner(System.in);

            System.out.println ("Enter single digit int ");
            int entry = keyboard.nextInt();


            System.out.println("Your number is " + entry);
            System.out.println("Your number is " );

            System.out.println("The final result is " + r);

            }


}

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不能调用非静态函数或从静态函数引用非静态变量

所以基本上你必须写作

public static int attempt ....
static int r = ...

问题是静态方法在类测试上运行，而非静态方法在类测试的实例上运行

import java.util.Scanner;

public class test {


// this function should be static
public static int attempt (int b) {
        //b for entry, since b is the name of the variable
        return 3 + b;
}


public static void main (String[] args){
        Scanner keyboard = new Scanner(System.in);

        System.out.println ("Enter single digit int ");
        int entry = keyboard.nextInt();

        //put this in your main function
        int r = attempt(entry);
        System.out.println("Your number is " + entry);
        System.out.println("Your number is " );

        System.out.println("The final result is " + r);

        }
}

我认为你应该学习一些java教程