ArrayList类contains()方法 (ArrayList Class contains() method)

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

  contains()方法在java.util包中可用。

• contains() method is used to check whether this Arraylist contains the given object or not.

  contains()方法用于检查此Arraylist是否包含给定的对象。

• contains() 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.

  contains()方法是一种非静态方法，因此可以通过类对象进行访问，如果尝试使用类名称访问该方法，则会收到错误消息。

• contains() method does not throw an exception at the time of checking the given object in this Arraylist.

  在检查此Arraylist中的给定对象时， contains()方法不会引发异常。

Syntax:

句法：

    public boolean contains(Object obj);

Parameter(s):

参数：

• Object obj – represents the object to be checked whether exists or not exists in this Arraylist.

  Object obj –表示要检查的对象是否存在于此Arraylist中。

Return value:

返回值：

The return type of this method is boolean, it returns true if the given object exists in this Arraylist otherwise, it returns false when the given object does not exist in this Arraylist.

此方法的返回类型是布尔值 ，如果在此ArrayList中存在的给定对象，否则返回true，当给定的对象并不在此ArrayList存在返回false。

Example:

例：

// Java program to demonstrate the example
// of boolean contains() method of ArrayList
import java.util.*;
public class ContainsOfArrayList {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 contains(Object) method is to check
// the existence of the given object
boolean status = arr_l.contains("C++");
// Display status of the given object
System.out.println("arr_l.contains(C++):  " + status);
}
}

Output

输出量

ArrayList Elements: [C, C++, JAVA, DOTNET, PHP]
arr_l.contains(C++):  true

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