<1>实例操作一：返回不可变的集合
Collections类中可以返回空的List、Set、Map集合，但是通过这种方式返回的对象是无法进行增加数据的，因为在这些操作中并没有实现add()方法
import java.util.Collections;
import java.util.List;
import java.util.Set;
//=================================================
// File Name : Collection_demo
//------------------------------------------------------------------------------
// Author : Common
//主类
//Function : Collection_demo;
public class Collection_demo {
public static void main(String[] args) {
// TODO 自动生成的方法存根
List<String> allList = Collections.emptyList(); //返回不可变的空List集合
Set<String> allSet = Collections.emptySet(); //返回不可变的空List集合
}
}
<2>实例操作二：为集合增加内容
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
//=================================================
// File Name : Collection_demo
//------------------------------------------------------------------------------
// Author : Common
//主类
//Function : Collection_demo;
public class Collection_demo {
public static void main(String[] args) {
// TODO 自动生成的方法存根
List<String> all = new ArrayList<String>(); //实例化List
Collections.addAll(all, "zhangsan","lisi","wangwu"); //增加内容
Iterator<String> iter = all.iterator(); //实例化iterator对象
while(iter.hasNext()){
System.out.println(iter.next()+"、");
}
}
}
<3>实例操作三：反转集合中的内容
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
//=================================================
// File Name : Collection_demo
//------------------------------------------------------------------------------
// Author : Common
//主类
//Function : Collection_demo;
public class Collection_demo {
public static void main(String[] args) {
// TODO 自动生成的方法存根
List<String> all = new ArrayList<String>(); //实例化List
Collections.addAll(all, "zhangsan","lisi","wangwu"); //增加内容
Collections.reverse(all); //内容反转保存
Iterator<String> iter = all.iterator(); //实例化iterator对象
while(iter.hasNext()){
System.out.println(iter.next()+"、");
}
}
}
<4>实例操作四：检索内容
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
//=================================================
// File Name : Collection_demo
//------------------------------------------------------------------------------
// Author : Common
//主类
//Function : Collection_demo;
public class Collection_demo {
public static void main(String[] args) {
// TODO 自动生成的方法存根
List<String> all = new ArrayList<String>(); //实例化List
Collections.addAll(all, "zhangsan","lisi","wangwu"); //增加内容
Collections.reverse(all); //内容反转保存
Iterator<String> iter = all.iterator(); //实例化iterator对象
while(iter.hasNext()){
System.out.println(iter.next()+"、");
}
int point = Collections.binarySearch(all,"zhangsan");
System.out.println("检索结果："+point); //输出位置
}
}
<5>实例操作五：替换集合中的内容
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
//=================================================
// File Name : Collection_demo
//------------------------------------------------------------------------------
// Author : Common
//主类
//Function : Collection_demo;
public class Collection_demo {
public static void main(String[] args) {
// TODO 自动生成的方法存根
// List<String> allList = Collections.emptyList(); //返回不可变的空List集合
// Set<String> allSet = Collections.emptySet(); //返回不可变的空List集合
List<String> all = new ArrayList<String>(); //实例化List
Collections.addAll(all, "zhangsan","lisi","wangwu"); //增加内容
Collections.replaceAll(all, "wangwu", "lisi"); //替换内容
Collections.reverse(all); //内容反转保存
Iterator<String> iter = all.iterator(); //实例化iterator对象
while(iter.hasNext()){
System.out.println(iter.next()+"、");
}
int point = Collections.binarySearch(all,"zhangsan");
System.out.println("检索结果："+point); //输出位置
}
}
原文：http://www.cnblogs.com/tonglin0325/p/5287523.html