Question

我正在尝试获取两个浮点值，查看哪一个更大，并返回true或false。这是我的代码：

import java.util.Scanner;

public class Four_Ten
{
    public static void main(String []args){
        double num1, num2 = 0;

        Scanner scan = new Scanner(System.in);

        System.out.println("Enter a floating point value:");
        num1 = scan.nextFloat();
        System.out.println("Enter another floating point value:");
        num2 = scan.nextFloat();
        System.out.println(calcGreater(num1, num2));
    }

    public double calcGreater(double a, double b){
        boolean greater = false;
        if (a > b){
            greater = true;
        }
        if (b > a){
            greater = false;
        }
        return greater;
    }
}

我收到以下错误：

non-static method calcGreater(double, double) cannot be referenced from a static context

我该如何解决这个问题？

Answer 1

public class Four_Ten
{
    public static void main(String []args){
    double num1, num2 = 0;

    Scanner scan = new Scanner(System.in);

    System.out.println("Enter a floating point value:");
    num1 = scan.nextFloat();
    System.out.println("Enter another floating point value:");
    num2 = scan.nextFloat();
    Four_Ten obj=new Four_Ten();
    System.out.println(obj.calcGreater(num1, num2));
}

public double calcGreater(double a, double b){
    boolean greater = false;
    if (a > b){
        greater = true;
    }
    if (b > a){
        greater = false;
    }
    return greater;
}
}

Answer 2

尝试添加关键字static，它是boolean而不是double -

public static boolean calcGreater(double a, double b){
  // return (a > b); /* why not a > b? */
  boolean greater = false;
  if (a > b){
    greater = true;
  }
  if (b > a){
    greater = false;
  }
  return greater;
}

Answer 3

public double calcGreater(double a, double b)不是static方法，因此您无法从non-static method.add static关键字调用static方法calcGreater()如下

public static double calcGreater(double a, double b)

或

实例化对象和调用方法如下

Four_Ten a=new Four_Ten();
a.calcGreater(double a, double b);

不仅如此：返回类型不匹配

public double calcGreater(double a, double b){ // expected return type double 
    boolean greater = false;
    if (a > b){
        greater = true;
    }
    if (b > a){
        greater = false;
    }
    return greater;  // you are returning boolean
}

Answer 4

创建类Four_Ten的对象，然后调用类似

的方法

Four_Ten obj = new Four_Ten();
obj.calcGreater(num1,num2);

您收到错误，因为静态成员无法直接访问非静态成员。在这种情况下，main（）是静态的，calcGreater（）是非静态的，因此您需要一个对象来访问静态main（）函数中的非静态函数calcGreater（）。

基本多类Java程序出错

4 个答案: