Question

我有一个java列表，我需要在添加对象后对其进行排序。该对象有三个要素。一个字符串和两个整数。该课程如下： -

public class ValueWords implements Comparable<ValueWords>{

//.............................................

public static final Comparator<ValueWords> valComparator = new Comparator<ValueWords>()
 {@Override
    public int compare(ValueWords v1, ValueWords v2) {
        return v1.valWord   - v2.valWord; }
   }
};
//....................................................................
private String strWord;
private int valWord;
private int phraseWord;
public int getPhraseWord() {
    return phraseWord;}
public void setPhraseWord(int phraseWord) {
    this.phraseWord = phraseWord;}
public String getStrWord() {
    return strWord;}
public void setStrWord(String strWord) {
    this.strWord = strWord;}
public int getValWord() {
    return valWord;}
public void setValWord(int valWord) {
    this.valWord = valWord;}
public ValueWords() {}

@Override
public int compareTo(ValueWords arg0) {
    // TODO Auto-generated method stub
    return 0;}
//..............................................
}

我称之为

 Collections.sort(valWordList,ValueWords.valComparator);

它为我提供了如下排序列表： -

 ---------------------------------------------
   strWord     valWord      phraseWord
   abcd          0             1
   abcde         0             0
   mns           1             2 
   efgh          1             1
   xyz           2             2
   zxx           2             0
  --------------------------------------------

我想要一个嵌套排序，如： -

  ---------------------------------------------
   strWord     valWord      phraseWord
   abcde        0             0
   abcd         0             0
   efgh         1             1 
   mns          1             2
   zxx          2             0
   xyz          2             2
  --------------------------------------------

我跟着做了一些徒劳的尝试，但是对java很新。他们没有工作。他们很安静，可以放在这里。

Answer 1

尝试更改比较器以检查两个值：

public static final Comparator<ValueWords> valComparator = new Comparator<ValueWords>() {
    @Override
    public int compare(ValueWords v1, ValueWords v2) {
        if(v1.valWord == v2.valWord)
            return v1.phraseWord - v2.phraseWord;
        else 
            return v1.valWord - v2.valWord;
    }
};

Answer 2

您可以将它们组合在一个比较器中：

public static final Comparator<ValueWords> valComparator = new Comparator<ValueWords>()
{
    @Override
    public int compare(ValueWords v1, ValueWords v2) {
        int result = Integer.compare(v1.valWord, v2.valWord);
        return result == 0 ? Integer.compare(v1.phraseWord, v2.phraseWord) : result;
    }
};

在java 8+中，您还可以使用Comparator.thenComparing组合2个比较器：

valComparator = ((Comparator<ValueWords>) (v1, v2) -> Integer.compare(v1.valWord, v2.valWord))
                                         .thenComparing((v1, v2) -> Integer.compare(v1.phraseWord, v2.phraseWord));

Java List中的嵌套排序基于两个元素使用Comparator

2 个答案: