数组部分拷贝和全靠背

import java.util.Arrays;

class Main{
    public static void main(String[] args) {
        int[] num1 = {1,2,3,4,5};
        int[] num2 = {4,5,6};
       // System.arraycopy(num1,1,num2,0,3);//部分拷贝，移花接木，替代目标数组内容
//        for (int n : num2){
//            System.out.print(n+" ");
//        }
        //2 3 4超过目标数组长度会报越界异常
        int[] num3 = Arrays.copyOf(num1,4);
                for (int n : num3){
            System.out.print(n+" ");
        }
    }
}