Java中的动态定义数组

package dongtai;

import java.util.Scanner;
import java.util.ArrayList;

public class DongTai {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        ArrayList<Integer> p = new ArrayList<>();   //创建一个ArrayList
        int n = scan.nextInt();   
        for(int i=0; i<n+1; i++)  
        {
            p.add(0);     //往p数组里面添加元素
        }
        for(int j=0; j<n+1; j++)  
        {
            p.set(j, scan.nextInt());  //键盘端输入数组的元素大小
        }

package dongtai;

import java.util.Scanner;

public class DongTai {
    public static int []p;   //直接定义一个一维数组
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        p = new int[num];  //可直接定义数组大小
    }
}

package dongtai;

import java.util.Scanner;

public class DongTai {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        int [][] m;
        m = new int[n][];
        for(int i=1; i<n; i++)        //前两个n位第一维，后两个n为第二维
        {
            m[i] = new int[n];        //动态创建第二维
            for(int j=1; j<n; j++)
            {
                m[i][j] = 0;
            }
        }
    }
}

package dongtai;

import java.util.Scanner;

public class DongTai {
    public static int arr[][][]; 
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        arr = new int[n][n][n];
    }
}