Question

我一直在使用可比较的类来运行并正确比较，但是当我尝试打印出值时，它会给我内存地址。我知道这可以通过toString方法修复，但我不确定如何去做。这是我的代码：

import java.io.*;
import java.util.*;
import java.lang.Object;

public class StreetAddress implements Comparable<StreetAddress>
{
    protected int num;
    protected String stName;

    public StreetAddress(int n, String s){
    num = n;
    stName = s;
    }

    public int getNum(){
        // returns the street number
        return num;
    }

    public String getName(){
        // returns the street name
        return stName;
    }

    public int compareTo(StreetAddress street) throws ClassCastException{
        // exception prevents crash if an address is not compared to
        // another address
        int compareName = this.stName.compareTo(street.stName);
        int compareNum = this.num - street.num;
        if (compareName < 0){
            // first address comes after compared address
            return compareName;
        }

        else if (compareName == 0){ // same address name
            if (compareNum < 0){
                System.out.println(this.num + "" + this.stName + ", " + street.num + "" + street.stName);
                return compareName;
            }
            else{
                System.out.println("");
                return compareName;
            }
        }

        else{
            // first address comes before compared address
            return compareName;
        }

        }

    public static void main(String args[])
    {
    StreetAddress add1 = new StreetAddress(7864, "cartesian road");
    StreetAddress add2 = new StreetAddress(5141, "cartesian road");
    StreetAddress add3 = new StreetAddress(1664, "n kings street");
    StreetAddress add4 = new StreetAddress(9753, "pioneer parkway");
    StreetAddress add5 = new StreetAddress(3643, "starry avenue");
    add1.compareTo(add2);
    add4.compareTo(add1);
    add3.compareTo(add3);
    add2.compareTo(add5);
    }
}

Answer 1

简单：

@Override
public String toString() {
    return String.format("%d %s", num, stName);
}

@Override注释不是必需的，但绝对是好的做法。请注意，String.format("%d %s", num, stName)会生成"[num] [street]"形式的字符串。如果你想在将来做出改变，我发现String.format比字符串连接提供了更大的灵活性。

Answer 2

@Override
public String toString() {
   return "StreetAddress: num= " + num + ", stName=" + stName ;
}

用toString java返回一个字符串

2 个答案: