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package com; import java.util.Comparator; import java.util.TreeMap; public class Test5 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub TreeMap<String, String> tree = new TreeMap<String, String>( new Comparator<Object>() { @Override public int compare(Object o1, Object o2) { // TODO Auto-generated method stub if (o1 == null || o2 == null ){ return 0 ; } return o1.toString().compareTo(o2.toString()); } } ); tree.put( "k" , "1" ); tree.put( "ba" , "2" ); tree.put( "z" , "3" ); tree.put( "d" , "4" ); tree.put( "e" , "5" ); tree.put( "an" , "6" ); tree.put( "c" , "7" ); for (String str : tree.keySet()){ System.out.println(str); } } } |
經(jīng)測試默認(rèn)是按照 KEY 進(jìn)行排序的。
但是可以寫對象比較器,進(jìn)行自定義排序。
TreeSet : 自定義倒序排序,默認(rèn)按照正序排序,1,2,3,4,5,6
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package com; import java.util.Comparator; import java.util.TreeSet; public class Test6 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub TreeSet<Object> tree = new TreeSet<Object>( new Comparator<Object>() { @Override public int compare(Object o1, Object o2) { // TODO Auto-generated method stub if (o1 == null || o2 == null ){ return 0 ; } if (Integer.parseInt(o1.toString()) > Integer.parseInt(o2.toString())){ return - 1 ; } else if (Integer.parseInt(o1.toString()) < Integer.parseInt(o2.toString())){ return 1 ; } else { return 0 ; } } }); tree.add( 4 ); tree.add( 5 ); tree.add( 6 ); tree.add( 1 ); tree.add( 2 ); tree.add( 3 ); for (Object o : tree){ System.out.println(o); } } } |
以上這篇淺談java中的TreeMap 排序與TreeSet 排序就是小編分享給大家的全部內(nèi)容了,希望能給大家一個參考,也希望大家多多支持服務(wù)器之家。