用toString返回一个字符串java

Question

我一直在使用一个可比较的类来正确运行和比较，但是当我尝试打印这些值时，它给了我内存地址。我知道这可以通过toString方法解决，但我不确定如何去做。这里是我的代码：

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); 
} 

的@Override注释是没有必要的，但它肯定是很好的做法。请注意，String.format("%d %s", num, stName)会生成"[num] [street]"的字符串。如果您想在将来进行更改，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 ; 
}