ArrayList类isEmpty()方法 (ArrayList Class isEmpty() method)

• isEmpty() method is available in java.util package.

  isEmpty()方法在java.util包中可用。

• isEmpty() method is used to check whether this Arraylist is "empty" or "not empty".

  isEmpty()方法用于检查此Arraylist是“空”还是“非空”。

• isEmpty() method is a non-static method so it is accessible with the class object and if we try to access the method with the class name then we will get an error.

  isEmpty()方法是一个非静态方法，因此可以通过类对象进行访问，如果尝试使用类名访问该方法，则会收到错误消息。

• isEmpty() method does not throw an exception at the time of checking the status of an empty Arraylist.

  在检查空Arraylist的状态时， isEmpty()方法不会引发异常。

Syntax:

句法：

    public boolean isEmpty();

Parameter(s):

参数：

• It does not accept any parameter.

  它不接受任何参数。

Return value:

返回值：

The return type of this method is boolean, it returns true when this Arraylist is "empty" otherwise it returns false when this Arraylist is "non-empty".

此方法的返回类型为boolean ，当此Arraylist为“空”时返回true；否则，当此Arraylist为“非空”时返回false。

Example:

例：

// Java program to demonstrate the example
// of boolean isEmpty() method of ArrayList
import java.util.*;
public class EmpytArrayList {public static void main(String[] args) {// Create an ArrayList with initial
// capacity of storing elements
ArrayList arr_l = new ArrayList(10);
// By using add() method is to add
// elements in this ArrayList
arr_l.add("C");
arr_l.add("C++");
arr_l.add("JAVA");
arr_l.add("DOTNET");
arr_l.add("PHP");
// Display ArrayList
System.out.println("ArrayList Elements :" + arr_l);
// By using isEmpty() method is to check
// the empty ArrayList
boolean status = arr_l.isEmpty();
// Display status of the given ArrayList
System.out.println("arr_l.isEmpty() : " + status);
}
}

Output

输出量

ArrayList Elements :[C, C++, JAVA, DOTNET, PHP]
arr_l.isEmpty() : false

翻译自: https://www.includehelp.com/java/arraylist-isempty-method-with-example.aspx