m0_65594779的博客

自定义排序

自然排序

import java.util.*;public class Example {public static void main(String[]args) { ArrayList list=new ArrayList(); list.add("张三"); list.add("李四"); list.add("王五"); for(Object obj:list) { System.out.println(obj); }}}运行结果：张三李四王五注：foreach,

import java.util.TreeSet;public class Example {public static void main(String[]args) { TreeSet ts=new TreeSet(); ts.add(3); ts.add(29); ts.add(101); ts.add(21); System.out.println(ts);//集合 //获取首尾元素 System.out.println(ts.first()); Sy

import java.util.*;public class Example {public static void main(String[]args) { LinkedHashSet set=new LinkedHashSet(); set.add("张三"); set.add("李四"); set.add("王五"); Iterator it=set.iterator(); while(it.hasNext()) { Object obj=it.next(); System

import java.util.*;class Student{ String id; String name; public Student(String id,String name) { this.id=id; this.name=name; } public String toString() { return id+":"+name; } //重写hashCode()方法 public int hashCode() { return id.hashCode()

import java.util.*;class Student{ String id; String name; public Student(String id,String name) { this.id=id; this.name=name; } public String toString() { return id+":"+name; }}public class Example {public static void main(String[]args) {

import java.util.*;public class Example {public static void main(String[]args) { HashSet hset=new HashSet(); hset.add("张三"); hset.add("李四"); hset.add("王五"); hset.add("李四"); Iterator it=hset.iterator(); while(it.hasNext()) { Object obj=it.next(

Iterator接口

LinkedList

ArrayList