java arrays arraycopy 复制数组

    public static void main(String args[]){
        int[] source = {1,2,3,4,5,6,7};
        int[] target = new int[5];
        System.arraycopy(source,0,target,0,5);// 6,7超出5的长度,被省略了

        System.out.println(Arrays.toString(target));

        for(int i = 0;i < target.length;i++){
            System.out.print(target[i] + "\t");
        }
    }

• arraycopy 来扩充数组

        String[] names = new String[] {"A","B","C"};
        String[] extended = new String[5];
        System.arraycopy(names,0,extended,0,names.length);// 这只复制操作0,1,2位置
        extended[3] = "D";
        extended[4] = "E";
        for(String str : extended){
            System.out.println(str);
        }