Arrays are one of the important data structures for every programming language. Of course, different languages ??implement and process arrays differently. Arrays provided in the Java language are used to store fixed-size elements of the same type.
Java determines whether the array is empty:
public class Main {
public static void main(String[] args) {
int[] array1 = new int[]{}; //被當(dāng)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(dāng)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(zhǎng)度
System.out.println("array2[0].length == 0");
}
System.out.println("-----------------------------");
Integer[] array3 = new Integer[]{}; //被當(dāng)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(dāng)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(zhǎng)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*/One-dimensional array needs to be judged according to the length of the array. If it is 0, it is empty, and vice versa;
Two-dimensional array needs to Judging based on the array length in the first line, if it is 0, it is empty, and vice versa;
For more java knowledge, please pay attention to java basic tutorial.
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