替换HashSet Java成员 [英] Replacing a HashSet Java member

问题描述

我有那个结构的集合。我没有重复，但是当我打电话：
set.add（element） - >并且已经有确切的元素我希望旧的被替换。

I have Set of that structure. I do not have duplicates but when I call: set.add(element) -> and there is already exact element I would like the old to be replaced.

import java.io.*;

public class WordInfo implements Serializable {
    File plik;
    Integer wystapienia;

    public WordInfo(File plik, Integer wystapienia) {
        this.plik = plik;
        this.wystapienia = wystapienia;
    }

    public String toString() {
    //  if (plik.getAbsolutePath().contains("src") && wystapienia != 0)
            return plik.getAbsolutePath() + "\tWYSTAPIEN " + wystapienia;
    //  return "";
    }
    @Override
    public boolean equals(Object obj) {
        if(this == obj) return true;
        if(!(obj instanceof WordInfo)) return false;
        return this.plik.equals(((WordInfo) obj).plik);
    }

    @Override
    public int hashCode() {        
        return this.plik.hashCode();
    }
}

推荐答案

每次添加前删除：

 someSet.remove(myObject);
 someSet.add(myObject);

删除将删除任何等于myObject的对象。或者，您可以检查添加结果：

The remove will remove any object that is equal to myObject. Alternatively, you can check the add result:

 if(!someSet.add(myObject)) {
     someSet.remove(myObject);
     someSet.add(myObject);
 }

哪个更有效取决于你碰撞的频率。如果它们很少见，第二种形式通常只进行一次操作，但是当发生碰撞时它会做三次。第一种形式总是两种。

Which would be more efficient depends on how often you have collisions. If they are rare, the second form will usually do only one operation, but when there is a collision it does three. The first form always does two.

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