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Java类集-list

     


    Collection 子接口:

    技术分享

     

    ArrayListList 接口和Collection接口的一个子类,用于实例化两种接口

     

    package leiji;

    import java.util.ArrayList;

    import java.util.List;

    import java.util.Collection;

    public class ArryList {

    public static void main(String args[]){

    List<String> arrlt=new ArrayList<String>();

    Collection<String> acoll=new ArrayList<String>();

    arrlt.add("Hello");

    arrlt.add(0,"World");

    System.out.println(arrlt);

    //添加元素

    acoll.add("jerry");

    acoll.add("weibo");

    //添加对象

    arrlt.addAll(acoll);

    arrlt.addAll(0,acoll);

    System.out.println(arrlt);

    //移除元素

    arrlt.remove(1);

    arrlt.remove("weibo");

    System.out.println(arrlt);

           

    //获取元素

    for(int i=0;i<=arrlt.size()-1;i++){

    //System.out.println(arrlt.get(i));

    }

    //String a[] =new String[]{"1","2"};

    //将集合变为对象数组

    String str[]=arrlt.toArray(new String[]{});  //

    for(int i=0;i<=str.length-1;i++){

    //System.out.println(str[i]);

    }

     

    Object obj[]=arrlt.toArray();

    for(int i=0;i<=obj.length-1;i++){

    System.out.println((String)obj[i]);

    }

    //推断是否为空

    System.out.println(arrlt.isEmpty());

    //推断是否包括某一个元素

    System.out.println(arrlt.contains("Hello")?"Hello is contains":"Hello is not contains");

    //截取子集合

    List l=arrlt.subList(1, 4);

    for(int i=0;i<l.size();i++){

    System.out.println(l.get(i));

    }

     

    System.out.println(l.indexOf("Hello"));

    }

     

    }

     

Java类集-list