Question

我想我需要做一些类型转换才能让粉丝输出toString，

为我的速度而不是1,2和3输出字符串。我不知道在哪里可以进行这些更改，要么在测试类中发送，要么在粉丝类中移动到私有。我试图在toString中添加一些调用，但我得到十六进制十进制结果。解决这个问题的一些不同方法非常有用。

public class Fan { 
    public final int SLOW = 1; 
    public final int MEDIUM = 2; 
    public final int FAST = 3; 

    private int speed; // = SLOW; 
    private boolean on; // on = false; 
    private double radius; // radius = 5; 
    private String color; // = "white"; 



    public int getSpeed ( ) {return speed; } 

    public void setSpeed ( int speed ) { this.speed = speed; } 

    public boolean isOn ( ) {return on; } 

    public void setOn ( boolean on) {this.on = on; } 

    public double getRadius ( ) {return radius; } 

    public void setRadius ( double radius ) { this.radius = radius; } 

    public String getColor ( ) { return color; } 

    public void setColor ( String color ) { this.color = color; } 

    public Fan ( ) { 
        System.out.println("Default constructor called");
    } 
    // default constructor

    public Fan ( int speed, boolean on, double radius, String color ) { 
       this.speed = speed;
       this.on = on;
       this.radius = radius;
       this.color = color;
       System.out.println("Overloaded constructor called");
    } 
    //overloaded constructor

    public String toString () { 
       String x = "speed is " + speed + ", is the fan turned on? " + on + ",the       radius "
        + "of the blades are " + radius + ", and the color of the fan is "   +      color;
       return x;
    } 

}

public class FanTest {


    public static void main(String[] args) {

        Fan f1 = new Fan( 3,  true, 10, "Yellow" )  ;
        Fan f2 = new Fan();
        Fan f4 = new Fan();
        f1.equals(f4) ;
        Fan f3 = f1;
        int slow = 1;
        int medium = 2;
        int fast = 3;

            System.out.println(f1);
            System.out.println(f2);
            System.out.println(f3);

        if (f1.equals(f3)) {
          System.out.println("Obejects r3 and r1 are the same\n");
        } else { 
          System.out.println("Objects r3 and r1 are different");
        }

        while (f1.equals(f4)) 
            f4.setOn(false);
            f4.setSpeed(2);
            f4.setColor("green");
            f4.setRadius(8);
            System.out.println(f4);
    }

}

Answer 1

首先，在默认构造函数中没有设置变量。这意味着使用默认构造函数创建的任何Fan对象都处于无效状态（例如，speed默认为0）。我建议你取消注释第9-12行：

private int speed = SLOW;
private boolean on = false;
private double radius = 5;
private String color = "white";

你说你想要为我的速度而不是1,2和3＆＃34;输出字符串。这可以使用if..else或switch轻松实现。

if (speed == 1) {
    str = str + " slow ";
} else if (speed == 2) {
    str = str + " medium ";
} else if (speed == 3) {
    str = str + " fast ";
}

使用开关：

switch (speed) {
    case 1:
        str = str + " slow ";
        break;
    case 2:
        str = str + " medium ";
        break;
    case 3:
        str = str + " fast ";
        break;
}

关于f1.equals(f4)：这些是不同的对象，因此永远不会true。

关于equals：equals是类Object中定义的方法，因此可以在任何对象上使用。但除非你覆盖它，否则会检查身份，这意味着

a.equals(b)

始终返回与

相同的内容

a == b

尝试更改某些数据类型以读取除数字以外的其他输出

1 个答案: