Java LinkedHashSet clear()方法及示例

java.util.LinkedHashSet 类的 clear() 方法是用来删除这个集合中的所有元素。在这个调用返回后，这个集合将是空的。

语法

public void clear()

返回值： 该方法 不返回 任何东西。

下面是一些例子来说明clear()方法。

例1 :

// Java program to demonstrate
// clear() method
// for Integer value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
        try {
  
            // Create the object of LinkedHashSet<Integer>
            LinkedHashSet<Integer>
                linkset = new LinkedHashSet<Integer>();
  
            // populate hash set
            linkset.add(10);
            linkset.add(20);
            linkset.add(30);
  
            // print the LinkedHashSet
            System.out.println("LinkedHashSet: "
                               + linkset);
  
            // clear set values
            // using clear() method
            linkset.clear();
  
            // print the LinkedHashSet
            System.out.println("LinkedHashSet after "
                               + "use of clear() method: "
                               + linkset);
        }
  
        catch (NullPointerException e) {
  
            System.out.println("Exception thrown : " + e);
        }
    }
}

输出:

LinkedHashSet: [10, 20, 30]
LinkedHashSet after use of clear() method: []

例2 :

// Java program to demonstrate
// clear() method
// for String value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
        try {
  
            // Create the object of LinkedHashSet<Integer>
            LinkedHashSet<String>
                linkset = new LinkedHashSet<String>();
  
            // populate hash set
            linkset.add("A");
            linkset.add("B");
            linkset.add("C");
  
            // print the LinkedHashSet
            System.out.println("LinkedHashSet: "
                               + linkset);
  
            // clear set values
            // using clear() method
            linkset.clear();
  
            // print the LinkedHashSet
            System.out.println("LinkedHashSet after "
                               + "use of clear() method: "
                               + linkset);
        }
  
        catch (NullPointerException e) {
  
            System.out.println("Exception thrown : " + e);
        }
    }
}

输出:

LinkedHashSet: [A, B, C]
LinkedHashSet after use of clear() method: []