java中二维数组的三种定义方式

方式1：采用 new 关键字直接创建

package pactice;
public class practices1 {
    public static void main(String[] args) {
            int[][] a= new int[2][3];
        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a[i].length; j++) {
                System.out.println(a[i][j]);
            }
        }
    }
}

方式2：从高维开始逐维创建

package pactice;
public class practices1 {
    public static void main(String[] args) {
            int[][] a= new int[2][];
            a[0]=new int[2];
            a[1]=new int[4];
        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a[i].length; j++) {
                System.out.println(a[i][j]);
            }
        }
    }
}

方式3：采用初始化语句块创建数组对象

package pactice;
public class practices1 {
    public static void main(String[] args) {
            int[][] a= {{1,2},{2,4,6}};
        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a[i].length; j++) {
                System.out.print(a[i][j]+" ");
            }
            System.out.println();
        }
    }
}