ArrayList類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()方法用于檢查此Arraylist是“空”還是“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()方法是一個非靜態方法，因此可以通過類對象進行訪問，如果嘗試使用類名訪問該方法，則會收到錯誤消息。

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

  在檢查空Arraylist的狀態時， isEmpty()方法不會引發異常。

Syntax:

句法：

    public boolean isEmpty();

Parameter(s):

參數：

• It does not accept any parameter.

  它不接受任何參數。

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".

此方法的返回類型為boolean ，當此Arraylist為“空”時返回true；否則，當此Arraylist為“非空”時返回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

輸出量

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

翻譯自: https://www.includehelp.com/java/arraylist-isempty-method-with-example.aspx