Java 从具有多个变量的方法返回值

我遇到的问题是，我不知道主要如何调用这些方法来使它们工作

首先，我问用户，在“publicstaticvoiduserinput”方法中，他希望计算它的面积是什么形状。用户有3个选项可供选择

然后有三种方法，一种是圆，一种是三角形，一种是正方形

public static void userInput(double radius, int base, int height, int side){

    int object = Integer.parseInt(JOptionPane.showInputDialog(
    "Enter 1 if you want to know the area of a circle."
    \nEnter 2 if you want to know the area of a triangle.
    \nEnter 3 if you want to know the area of a square"));

    if (object == 1){
        radius = Double.parseDouble(JOptionPane.showInputDialog("Enter the radius"));


    }else if (object == 2){
        base = Integer.parseInt(JOptionPane.showInputDialog("Enter the base"));
        height = Integer.parseInt(JOptionPane.showInputDialog("Enter the height"));


    }else if (object == 3){
        side = Integer.parseInt(JOptionPane.showInputDialog("Enter the side"));

    }
}


public static double circle(){
    double radio = 0;
    double circle = (radio * radio) * 3.14159265358; 
    JOptionPane.showMessageDialog(null, "The circle area is "+circle);
    return circle;
}

public static int triangle(){
    int base= 0; 
    int height= 0;
    int triangle = (base * height)/2;
    JOptionPane.showMessageDialog(null, "The triangle area is "+triangle);
    return triangle;
}

public static int square(){
    int side = 0;
    int square = side * side;
    JOptionPane.showMessageDialog(null, "The square area is "+square);
    return square;
}

public static void main(String[] args) {
    circle(userInput(radius));
    triangle(userInput(base, height));
    square(userInput(side));
}

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有人能推荐一本关于方法的好书吗？

希望这就是你想要的：

import javax.swing.JOptionPane;

public class NewClass1 {
    public void userInput(int x){



    if (x == 1){
        double radius = Double.parseDouble(JOptionPane.showInputDialog("Enter the radius"));
        System.out.println(circle(radius));


    }else if (x == 2){
        int base = Integer.parseInt(JOptionPane.showInputDialog("Enter the base"));
        int height = Integer.parseInt(JOptionPane.showInputDialog("Enter the height"));
        System.out.println(triangle(base,height));

    }else if (x == 3){
        int side = Integer.parseInt(JOptionPane.showInputDialog("Enter the side"));
        System.out.println(square(side));
    }
}


public static double circle(double radio){

    double circle = (radio * radio) * 3.14159265358; 
    JOptionPane.showMessageDialog(null, "The circle area is "+circle);
    return circle;
}

public static int triangle(int base,int height){
    int triangle = (base * height)/2;
    JOptionPane.showMessageDialog(null, "The triangle area is "+triangle);
    return triangle;
}

public static int square(int side){
    int square = side * side;
    JOptionPane.showMessageDialog(null, "The square area is "+square);
    return square;
}

public static void main(String[] args) {

    NewClass1 obj = new NewClass1();
    int object = Integer.parseInt(JOptionPane.showInputDialog(
    "Enter 1 if you want to know the area of a circle\nEnter 2 if you want to know the area of a triangle.\nEnter 3 if you want to know the area of a square"));
    obj.userInput(object);
}
}

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尝试对Java方法进行一些练习。

您在问题中粘贴的代码不完整，但根据您的问题：

从具有多个变量的方法返回值

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您可以使用类的对象返回多个变量。

这将帮助您了解Java方法，考虑到您是初学者，我建议您阅读一本解释所有语言的书，用Java或Head First Java思考应该非常适合您，请查看它们。“试着对Java方法进行一些实践。”这就是我本周要做的。我提供的答案正确吗？是的，谢谢。这两行对我来说是新的“NewClass1 obj=newnewclass1（）；”和“obj.userInput（object）；”第一行是在我创建类NewClass1的对象时。从类创建的每个对象都有该类中定义的所有方法。然后我将用户输入值对象传递给方法Userinput。此处通过if语句选择了所需多边形。有趣。“System.out.println”是绑定方法的工具。结构是c语言家族的一部分；它们不是java的一部分。在java中，您可以返回类的对象