public class Main {
    public static void main(String[] args) {
        int[] array1 = new int[]{}; //被當成 {0}
        if (array1 == null) {
            System.out.println("array1 == null");
        }
        System.out.println(array1.length);//行數(shù)
        if (array1.length == 0) {
            System.out.println("array1.length == 0");
        }
        System.out.println("-----------------------------");
        int[][] array2 = new int[][]{{}}; //被當成 {{0},{},{}}
        if (array2 == null) {
            System.out.println("array2 == null");
        }
        System.out.println(array2.length);//行數(shù)
        if (array2.length == 0) {
            System.out.println("array2.length == 0");
        }
        if (array2[0].length == 0) {//第一行的長度
            System.out.println("array2[0].length == 0");
        }
        System.out.println("-----------------------------");
        Integer[] array3 = new Integer[]{}; //被當成 {0}
        if (array3 == null) {
            System.out.println("array3 == null");
        }
        System.out.println(array3.length);//行數(shù)
        if (array3.length == 0) {
            System.out.println("array3.length == 0");
        }
        System.out.println("-----------------------------");
        int[][] array4 = new int[][]{{}}; //被當成 {{0},{},{}}
        if (array4 == null) {
            System.out.println("array4 == null");
        }
        System.out.println(array4.length);//行數(shù)
        if (array4.length == 0) {
            System.out.println("array4.length == 0");
        }
        if (array4[0].length == 0) {//第一行的長度
            System.out.println("array4[0].length == 0");
        }
    }
}
/*輸出：
0
array1.length == 0
-----------------------------
1
array2[0].length == 0
-----------------------------
0
array3.length == 0
-----------------------------
1
array4[0].length == 0*/