import java.util.Collections; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.TreeMap; public class TestCollection { public static void main(String[] args) { System.out.println("开始:"); Person person1 = new Person("马先生", 220181); Person person2 = new Person("李先生", 220193); Person person3 = new Person("王小姐", 220186); Map<Number, Person> map = new HashMap<Number, Person>(); map.put(person1.getId_card(), person1); map.put(person2.getId_card(), person2); map.put(person3.getId_card(), person3); // HashMap System.out.println("HashMap,无序:"); for (Iterator<Number> it = map.keySet().iterator(); it.hasNext();) { Person person = map.get(it.next()); System.out.println(person.getId_card() + " " + person.getName()); } // TreeMap System.out.println("TreeMap,升序:"); TreeMap<Number, Person> treeMap = new TreeMap<Number, Person>(); treeMap.putAll(map); for (Iterator<Number> it = treeMap.keySet().iterator(); it.hasNext();) { Person person = treeMap.get(it.next()); System.out.println(person.getId_card() + " " + person.getName()); } System.out.println("TreeMap,降序:"); TreeMap<Number, Person> treeMap2 = new TreeMap<Number, Person>(Collections.reverseOrder()); treeMap2.putAll(map); for (Iterator it = treeMap2.keySet().iterator(); it.hasNext();) { Person person = (Person) treeMap2.get(it.next()); System.out.println(person.getId_card() + " " + person.getName()); } System.out.println("结束!"); } }
Java TreeMap
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转载自ln-software.iteye.com/blog/2357051
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