treeset java_Java TreeSet contains（）方法与示例

野性酷女 2023-03-05 15:53 95阅读 0赞

treeset java

## TreeSet类contains()方法 **(**TreeSet 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 the given object (ob) exists or not in this TreeSet.
    
    **contains()方法**用于检查给定对象(ob)在此TreeSet中是否存在。
 *  **contains() method** is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
    
    **contains()方法**是一个非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。
 *  **contains() method** may throw an exception at the time of checking the given object exists.
    
    在检查给定对象存在时， **contains()方法**可能会引发异常。
 *   *  **ClassCastException:** This exception may throw when the given parameter is incompatible to compare.
        
        **ClassCastException：**当给定参数不兼容进行比较时，可能会引发此异常。
     *  **NullPointerException:** This exception may throw when the given parameter is null exists.
        
        **NullPointerException：**当给定参数为null时，可能引发此异常。

**Syntax:**

**句法：**

public boolean contains(Object ob);

**Parameter(s):**

**参数：**

*  Object ob – represents the object (ob) to be checked for existence in this TreeSet.
    
    对象ob –表示要检查的对象(ob)在此TreeSet中是否存在。

**Return value:**

**返回值：**

The return type of the method is boolean, it returns true when the given object (ob) exists in this TreeSet otherwise it returns false.

该方法的返回类型为boolean ，当给定对象(ob)存在于此TreeSet中时，返回true；否则返回false。

**Example:**

**例：**

// Java program to demonstrate the example 
    // of boolean contains(Object ob) method of TreeSet 
    
    import java.util.*;
    
    public class ContainsOfTreeSet {
        
        public static void main(String[] args) {
        
            // Instantiates a TreeSet object
            TreeSet < String > tree_set = new TreeSet < String > ();
    
            // By using add() method is to add
            // the given object of this TreeSet 
            tree_set.add("C");
            tree_set.add("C++");
            tree_set.add("JAVA");
            tree_set.add("PHP");
            tree_set.add("SFDC");
    
            // Display TreeSet
            System.out.println("TreeSet: " + tree_set);
    
            // By using contains() method is to 
            // check whether the given object exists
            // or not exists in this TreeSet
            boolean status = tree_set.contains("JAVA");
    
            // Display Status
            System.out.println("tree_set.contains(JAVA): " + status);
        }
    }

**Output**

**输出量**

TreeSet: [C, C++, JAVA, PHP, SFDC]
    tree_set.contains(JAVA): true

> 翻译自: [https://www.includehelp.com/java/treeset-contains-method-with-example.aspx][https_www.includehelp.com_java_treeset-contains-method-with-example.aspx]

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