Java judges that one-dimensional two-dimensional array is empty

There are two situations when a Java array is empty:

1. The array is null, the length of the array cannot be calculated at this time;

int[] array = null;  //数组类型的空引用，不指向任何对象

2. The array is not null, but there are no elements in the array; at this time, the length of the array is not 0;

int[] array= new int[0];  //数组引用一个长度为0的数组对象

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Therefore, the judgment of the one-dimensional two-dimensional array is as follows:

Determine if a one-dimensional array is empty

if(array==null||array.length==0)
 return 0;

The judgment of one-dimensional arrays can follow the two situations mentioned above.

Determine the two-dimensional array is empty

if((array==null||array.length==0)||(array.length==1&&array[0].length==0))
	return 0;

To determine whether a two-dimensional array is empty in Java, there are three cases to determine:

1. Whether the first address of the two-dimensional array is empty, that is, array==null;

2. Whether the two-dimensional array is {}, that is, when array.length==0;

3. Whether the two-dimensional array is { {}}, ie array.length=1&&array[0].length==0;