Question

我试图使用TreeMap计算一个简单的String Pair对象。

我尝试过在树形图中使用这个比较器，但它仍然给出了错误的输出，就像它将对象对象本身进行比较一样：

static class Comp implements Comparator<Pair>
{   
    public int compare(Pair s1, Pair s2)
    {   
        boolean c1 = s1.word1.equals(s2.word1),
               c2 = s1.word2.equals(s2.word2),
               c3 = s1.word1.equals(s2.word2),
               c4 = s1.word2.equals(s2.word1);

        if(c1 && c2 || c3 && c4)
            return 0;   
        else if((!c1 && !c2) || (!c3 && !c4))
            return s1.word1.compareTo(s2.word1);
        if(!c1)
            return s1.word1.compareTo(s2.word1);
        else if(!c2)
            return s1.word2.compareTo(s2.word2);
        else if(!c3)
            return s1.word1.compareTo(s2.word2);
        else if(!c4)
            return s1.word2.compareTo(s2.word1);    
        else
            return s1.word1.compareTo(s2.word1);
    }
}

示例输入为：

<"red", "blue"> , <"blue", "red">, <"red", "red">, <"gray","purple">, <"purple","gray">

应输出：

<"gray", "purple", 2>, <"red", "blue", 2> <"red", "red", 1>

相反，我得到：

<"gray", "purple", 1><"red", "blue", 2> <"red", "red", 1><"purple", "gray", 1>

Answer 1

我不确定您是如何对计数进行编码的，但排序的效果与预期的代码一样。我在下面的代码与您的代码之间看到的唯一区别是Comp类在我的代码中不是静态的。

import java.util.Comparator;
import java.util.Map;
import java.util.TreeMap;

public class ComparatorTest {

    public ComparatorTest() {
        Map<Pair, String> x = new TreeMap<>(new Comp());
        x.put(new Pair("red", "blue"), "one");
        x.put(new Pair("blue", "red"), "two");
        x.put(new Pair("red", "red"), "three");
        x.put(new Pair("gray", "purple"), "four");
        x.put(new Pair("purple", "gray"), "five");

        System.out.println(String.format("Print out Map - %s", x.toString()));

        for (Pair pair : x.keySet()) {
            System.out.println(String.format("Key value <%s, %s, %s>", pair.word1, pair.word2, x.get(pair)));
        }
    }

    public static void main(String[] args) {
        new ComparatorTest();
    }
}

class Pair {
    String word1 = null;
    String word2 = null;

    public Pair(String word1, String word2) {
        this.word1 = word1;
        this.word2 = word2;
    }

    @Override
    public boolean equals(Object obj) {
        if (!(obj instanceof Pair)) { return false; }

        Pair that = (Pair)obj;

        return ((this.word1.equals(that.word1) && this.word2.equals(that.word2)) || (this.word1.equals(that.word2) && this.word2.equals(that.word1)));
    }

    @Override
    public String toString() {
        return String.format("<%s, %s>", word1, word2);
    }
}

class Comp implements Comparator<Pair> {   
    public int compare(Pair s1, Pair s2) {   
        boolean c1 = s1.word1.equals(s2.word1),
               c2 = s1.word2.equals(s2.word2),
               c3 = s1.word1.equals(s2.word2),
               c4 = s1.word2.equals(s2.word1);

        if(c1 && c2 || c3 && c4)
            return 0;   
        else if((!c1 && !c2) || (!c3 && !c4))
            return s1.word1.compareTo(s2.word1);
        if(!c1)
            return s1.word1.compareTo(s2.word1);
        else if(!c2)
            return s1.word2.compareTo(s2.word2);
        else if(!c3)
            return s1.word1.compareTo(s2.word2);
        else if(!c4)
            return s1.word2.compareTo(s2.word1);    
        else
            return s1.word1.compareTo(s2.word1);
    }
}

输出

Print out Map - {<gray, purple>=five, <red, blue>=two, <red, red>=three}
Key value <gray, purple, five>
Key value <red, blue, two>
Key value <red, red, three>

如何在java中使用treemap对对象进行计数

1 个答案: