Java - 重写hashCode和toString(Java - Overriding hashCode and toString)

 当两个对象在等级A中具有相同的ele值时，那么这两个对象是相等的。 所以我重写了toString和hashCode来返回对象的ele （不考虑s的值）。 
 
public class A {
    private int ele;
    private String s;

    public int getEle() {
        return ele;
    }

    public void setEle(int ele) {
        this.ele = ele;
    }

    public String getS() {
        return s;
    }

    public void setS(String s) {
        this.s = s;
    }

    @Override
    public int hashCode(){
        return ele;
    }

    @Override
    public String toString() {
        return String.valueOf(ele);
    }
}
 
 
public static void main(String[] args) {

    Map<A, String> map = new HashMap<>();
    A a1 = new A();
    a1.setEle(10);
    a1.setS("abc");

    A a2 = new A();
    a2.setEle(10);
    a2.setS("efg");

    map.put(a1, "val1");
    map.put(a2, "val2");

    System.out.println(map.get(a1));
    System.out.println(map.get(a2));

}
 
 输出： 
 
val1
val2
 
 但是，如果我将a1和a2值放在地图中，我期望map.get(a1) map.get(a2) map.get(a1)和map.get(a2) map.get(a1)都返回val1或val2 。 

When two objects have same value of ele in class A then those two objects are equal. So I have overridden toString and hashCode to return the object's ele (not considering the value of s anywhere).
 
public class A {
    private int ele;
    private String s;

    public int getEle() {
        return ele;
    }

    public void setEle(int ele) {
        this.ele = ele;
    }

    public String getS() {
        return s;
    }

    public void setS(String s) {
        this.s = s;
    }

    @Override
    public int hashCode(){
        return ele;
    }

    @Override
    public String toString() {
        return String.valueOf(ele);
    }
}
 
 
public static void main(String[] args) {

    Map<A, String> map = new HashMap<>();
    A a1 = new A();
    a1.setEle(10);
    a1.setS("abc");

    A a2 = new A();
    a2.setEle(10);
    a2.setS("efg");

    map.put(a1, "val1");
    map.put(a2, "val2");

    System.out.println(map.get(a1));
    System.out.println(map.get(a2));

}
 
Output:
 
val1
val2
 
But if I put value of a1 and a2 in a map, I was expecting either val1 or val2 to be returned for both map.get(a1) and map.get(a2). 

原文：https://stackoverflow.com/questions/36290579