java数组-----拷贝掺入删除元素

Posted 2021-12-02 zzzao

package cn.zxg.arrays2;

/**
 * 测试数组的拷贝
 */
public class TestArrayCopy {
    public static void main(String[] args) {

        TestBaseCopy();
        TestBaseCopy2();
        String [] str={"阿里","京东","百度","亚马逊"};
        removeElment(str,1);

    }
    //数组的拷贝
    public  static  void  TestBaseCopy(){
        String [] str1={"aa","bb","cc","dd","ee"};
        String [] str2=new String[10];
        //从str1下标为2的位置复制3个到str2下标为4开始的位置
        System.arraycopy(str1,2,str2,4,3);

        for (String a:str2) {
            System.out.println(a);
        }
    }
    //数组元素的删除(其实也是数组的拷贝)
    public  static void TestBaseCopy2(){
        String [] str1={"aa","bb","cc","dd","ee"};
//        String [] str2=new String[];
        System.arraycopy(str1,3+1,str1,3, str1.length-3-1);
        str1[str1.length-1]=null;
        for (String i:str1
             ) {
            System.out.println(i);

        }


    }
    //删除数组中指定的索引位置的元素，并将原数组返回
    public  static String[] removeElment(String[] s,int index){
        System.arraycopy(s,index+1,s,index,s.length-index-1);
        s[s.length-1]=null;
        for (int i=0;i<s.length;i++){
            System.out.println(s[i]);
        }
        return  s;
    }
    //数组的扩容（本质：先定义一个更大的数组，将原数组原封不动拷贝到新数组中）
    public  static  void extendRange(){
        String[] str1={"aa","bb","cc"};
        String[] str2=new String[str1.length+10];
        System.arraycopy(str1,0,str2,0,str1.length);
        
        for (String temp:str2){
            System.out.println(temp);
        }
    }
    


}