JAVA集合

存储可变长度的数据时,数组不满足我们的需求,也适应不了变化的需求

所以引入了集合

集合的特点是:提供一种存储空间可变的存储模型,存储的数据容量可以发生改变

集合类:ArrayList,是一种特殊的数据类型,泛型

package Experience;

import java.util.ArrayList;

public class SpliceString {
    public static void main(String[] args){
        ArrayList arry=new ArrayList();
        System.out.println("arry:"+arry);
        //输出arry:[]
        //从索引0处开始
        arry.add("Hello,java");
        System.out.println("arry:"+arry);
        //在索引1处添加apple
        arry.add(1,"apple");
        //如果索引越界,那么会报错IndexOutOfBoundsException
        //arry.add(5,"apple");
        System.out.println("arry:"+arry);
    }
}

常用方法

package Experience;

import java.util.ArrayList;

public class SpliceString {
    public static void main(String[] args){
        ArrayList arry=new ArrayList();
        arry.add("apple");
        arry.add(1,"orange");
        arry.add("banana tomato potato");
        System.out.println(arry);
        arry.remove("orange");
        System.out.println(arry);
       //public boolean remove(Object o)删除指定元素,返回删除是否成功
        System.out.println(arry.remove("egg"));
        //public E remove(index) 删除指定索引的元素并返回
        System.out.println(arry.remove(1));
        //public E set(int index,Object o)修改指定索引元素,并且返回被修改的元素
        System.out.println(arry.set(0,"banana"));
        //public E get(int index)//返回指定索引处的元素
        System.out.println(arry.get(0));
        //public int size()//返回集合中元素的个数
        System.out.println(arry.size());
    }
}

遍历集合存储的字符串

package Experience;

import java.util.ArrayList;

public class ListString {
    public static void main(String[] args){
        ArrayList arry=new ArrayList();
        arry.add("apple");
        arry.add("banana");
        arry.add("orange");
        for(int i=0;i< arry.size();i++){
            System.out.println(arry.get(i));
        }
        System.out.println(arry.size());
    }
}

package Experience;

import java.util.ArrayList;

public class ListString {
    public static void main(String[] args){
        ArrayList st=new ArrayList();
        People s1=new People("小明",15);
        People s2=new People("小红",16);
        People s3=new People("小路",19);
        st.add(s1);
        st.add(s2);
        st.add(s3);
        for(int i=0;i 
 
 
 
 
 
 
 
 
 
 
 
					
										


					

						
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原文地址: http://outofmemory.cn/zaji/5712914.html