Java数组动态扩容的实现示例

import java.util.Scanner;
public class arrAdd {
    public static void main(String[] args) {
        Scanner myccanner=new Scanner(System.in);
        int arr[]={1,2,3};
        while (true){
            int arr2[]=new int [(arr.length)+1];
            for (int i=0;i<arr.length;i++){
                arr2[i]=arr[i];
            }
            System.out.println("请输入添加的值");
            int end =myccanner.nextInt();
            arr2[arr2.length-1]=end;
            arr=arr2;
            for (int j=0;j<arr.length;j++){
                System.out.print(arr[j]+" ");
            }
            System.out.println("是否继续添加y/n");
            char whether=myccanner.next().charAt(0);
            if (whether=='n'){
                break;
            }
        }
        System.out.println("不再添加");
    }
}

public class Demo1 {
	
	static int []array=new int [20];
	public static void main(String[] args){
 
		array=addLengthArray(array);
		for(int i = 0;i<array.length;i++){
			array[i]= i;
			System.out.println(array[i]);
		}
	}
 
	public static int[] addLengthArray(int[] array){
		int[] newArray = new int [array.length*2];
                //将array数组从0位置至array.length位置，复制到newArray数组0位置到array.length位置。
                System.arraycopy(array,0,newArray,0,array.length);
		return newArray;
	}
 
}