Java LinkedList clear() 方法

描述

Java LinkedList clear() 方法用于移除此列表中的所有元素。此调用返回后，列表将为空。

声明

以下是 java.util.LinkedList.clear() 方法的声明

public void clear()

参数

无

返回值

此方法不返回值。

异常

无

清空包含 Integer 的 LinkedList 示例

以下示例演示了 Java LinkedList clear() 方法的使用。在此示例中，我们使用 Integer。第一步，我们填充 linkedList 对象并打印它。然后我们打印 linkedList 对象的大小并执行清除操作。清除后，我们打印 linkedList 对象的大小，现在为 0。

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {
     
      // create an empty linked list
      LinkedList<Integer> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add(20);
      linkedList.add(30);
      linkedList.add(10);

      // let us print all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);    

      // finding size of this linkedList
      int retval = linkedList.size();
      System.out.println("LinkedList consists of "+ retval +" elements");

      System.out.println("Performing clear operation !!");
      linkedList.clear();
      retval = linkedList.size();
      System.out.println("Now, LinkedList consists of "+ retval +" elements");
   }
}   

输出

让我们编译并运行以上程序，这将产生以下结果：

LinkedList = [20, 30, 10]
LinkedList consists of 3 elements
Performing clear operation !!
Now, LinkedList consists of 0 elements

清空包含 String 的 LinkedList 示例

以下示例演示了 Java LinkedList clear() 方法的使用。在此示例中，我们使用 String。第一步，我们填充 linkedList 对象并打印它。然后我们打印 linkedList 对象的大小并执行清除操作。清除后，我们打印 linkedList 对象的大小，现在为 0。

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {
     
      // create an empty linked list
      LinkedList<String> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add("A");
      linkedList.add("B");
      linkedList.add("C");

      // let us print all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);    

      // finding size of this linkedList
      int retval = linkedList.size();
      System.out.println("LinkedList consists of "+ retval +" elements");

      System.out.println("Performing clear operation !!");
      linkedList.clear();
      retval = linkedList.size();
      System.out.println("Now, LinkedList consists of "+ retval +" elements");
   }
}   

输出

让我们编译并运行以上程序，这将产生以下结果：

LinkedList = [A, B, C]
LinkedList consists of 3 elements
Performing clear operation !!
Now, LinkedList consists of 0 elements

清空包含 Object 的 LinkedList 示例

以下示例演示了 Java LinkedList clear() 方法的使用。在此示例中，我们使用 Student 对象。第一步，我们填充 linkedList 对象并打印它。然后我们打印 linkedList 对象的大小并执行清除操作。清除后，我们打印 linkedList 对象的大小，现在为 0。

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {
     
      // create an empty linkedList
      LinkedList<Student> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add(new Student(1, "Julie"));
      linkedList.add(new Student(2, "Robert"));
      linkedList.add(new Student(3, "Adam"));

      // let us print all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);    

      // finding size of this linkedList
      int retval = linkedList.size();
      System.out.println("linkedList consists of "+ retval +" elements");

      System.out.println("Performing clear operation !!");
      linkedList.clear();
      retval = linkedList.size();
      System.out.println("Now, linkedList consists of "+ retval +" elements");
   } 		
} 

class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
}  

输出

让我们编译并运行以上程序，这将产生以下结果：

LinkedList = [[ 1, Julie ], [ 2, Robert ], [ 3, Adam ]]
linkedList consists of 3 elements
Performing clear operation !!
Now, linkedList consists of 0 elements