Java 一维数组的拷贝

1.for循环;

import java.util.Arrays;
public class TestDemo {
    public static void main(String[] args) {
        int[] arr = new int[]{1,2,3,4,5};
        int[] brr = new int[arr.length];
        for (int i = 0;i < arr.length;i++) {
            brr[i] = arr[i];
        }
        System.out.println(Arrays.toString(arr));
        System.out.println(Arrays.toString(brr));
    }
}

2.数组名.clone();

import java.util.Arrays;
public class TestDemo {
    public static void main(String[] args) {
        int[] arr = new int[]{1,2,3,4,5};
        int[] brr = arr.clone();
        arr[0] = 10;
        System.out.println(Arrays.toString(arr));
        System.out.println(Arrays.toString(brr));
    }
}

3.Arrays.copyOf();实现数组的扩容和缩容
查看Arrays类中copyOf函数
在copyOf函数中传入原数组original和新的数组长度newlength，在函数中先开辟一个和原数组数据类型相同的且长度为newlength数组，调用System.arraycopy()方法，从原数组的0号下标开始向新数组的0号下标开始复制，复制的长度为两个数组长度的最小值

    public static int[] copyOf(int[] original, int newLength) {
        int[] copy = new int[newLength];
        System.arraycopy(original, 0, copy, 0,
                         Math.min(original.length, newLength));
        return copy;
    }

示例：

import java.util.Arrays;
public class TestDemo {
    public static void main(String[] args) {
        int[] arr = new int[]{1,2,3,4,5};
        int[] brr = Arrays.copyOf(arr,arr.length);
        arr[0] = 10;
        System.out.println(Arrays.toString(arr));
        System.out.println(Arrays.toString(brr));
        System.out.println("arr数组名保存:"+arr+" brr数组名保存:"+brr);
    }
}

4. System.arraycopy(src, srcPos, dest, destPos, length);

import java.util.Arrays;

public class TestDemo {
    public static void main(String[] args) {
        int[] arr = new int[]{1,2,3,4,5};
        int[] brr = new int[arr.length];
        System.arraycopy(arr,0,brr,0,arr.length);
        System.out.println(Arrays.toString(arr));
        System.out.println(Arrays.toString(brr));
        System.out.println("arr数组名保存:"+arr+" brr数组名保存:"+brr);
    }
}