Java-Iterator遍历集合

Java-Iterator遍历集合

import java.util.ArrayList;import java.util.HashMap;import java.util.HashSet;import java.util.Iterator;import java.util.List;import java.util.Map;import java.util.Map.Entry;import java.util.Set;public class TestIterator { public static void main(String[] args) { //testIteratorList(); //testIteratorSet(); testIteratorMap(); } public static void testIteratorList() { List list = new ArrayList<>(); list.add("aa"); list.add("bb"); list.add("cc"); for (Iterator item = list.iterator(); item.hasNext();) { String temp = item.next(); System.out.println(temp); } } public static void testIteratorSet(){ Set set=new HashSet<>(); set.add("11"); set.add("22"); set.add("33"); for(Iterator iter=set.iterator();iter.hasNext();){ String temp=iter.next(); System.out.println(temp); } } //第一种 public static void testIteratorMap(){ Map map=new HashMap<>(); map.put(100, "aa"); map.put(400, "bb"); map.put(500, "cc"); Set> ss=map.entrySet(); for(Iterator> iter= ss.iterator();iter.hasNext();){ Entry temp=iter.next(); System.out.println(temp.getKey()+"--"+temp.getValue()); } //第二種 Set keySet=map.keySet(); for(Iterator iter=keySet.iterator();iter.hasNext();){ Integer key=iter.next(); System.out.println(key+"-------"+map.get(key)); } }}

TreeSet实现排序：

import java.util.Set;import java.util.TreeSet;public class TestTreeSet {public static void main(String[] args) { Set set=new TreeSet<>(); set.add(300); set.add(200); set.add(600); for(Integer m:set) System.out.println(m); Set set2 = new TreeSet<>(); set2.add(new Emp2(100,"张三",3000)); set2.add(new Emp2(50,"李四",2000)); set2.add(new Emp2(150,"王五",8000)); set2.add(new Emp2(30,"赵六",20000)); for(Emp2 m:set2){ System.out.println(m); }}}class Emp2 implements Comparable { int id; String name; double salary; public Emp2(int id, String name, double salary) { super(); this.id = id; this.name = name; this.salary = salary; } @Override public String toString() { return "id:"+id+",name:"+name+",salary:"+salary; } @Override public int compareTo(Emp2 o) { //负数：小于，0：等于，正数：大于 if(this.salary>o.salary){ return 1; }else if(this.salaryo.id){ return 1; }else if(this.id

TreeMap实现排序：

import java.util.Map;import java.util.TreeMap;public class TestTreeMap { public static void main(String[] args) { Map treeMap1=new TreeMap(); treeMap1.put(20, "aa"); treeMap1.put(3, "bb"); treeMap1.put(6, "cc"); for(Integer key:treeMap1.keySet()){ System.out.println(key+"----"+treeMap1.get(key)); } Map treeMap2=new TreeMap(); treeMap2.put(new Employee(100,"張三",5000), "111"); treeMap2.put(new Employee(200,"李四",500), "222"); treeMap2.put(new Employee(150,"王五",6000), "333"); //按照key遞增的方式排序 for(Employee key:treeMap2.keySet()){ System.out.println(key+"---"+treeMap2.get(key)); } }}class Employee implements Comparable{ int id; String name; double salary; public Employee(int id, String name, double salary) { super(); this.id = id; this.name = name; this.salary = salary; } @Override public String toString() { return "id:"+id+",name:"+name+",salary:"+salary; } @Override public int compareTo(Employee o){ if(this.salary>0)return 1; else if(this.salaryo.id)return 1; else if(this.id

版权声明：本文内容由网络用户投稿，版权归原作者所有，本站不拥有其著作权，亦不承担相应法律责任。如果您发现本站中有涉嫌抄袭或描述失实的内容，请联系我们jiasou666@gmail.com 处理，核实后本网站将在24小时内删除侵权内容。