Clear array list in Java using clear() method of ArrayList class

Use the clear() method of the ArrayList class to clear the array list in Java

In Java programming, we often use the ArrayList class to manage and operate array lists. Sometimes, we may need to clear an existing array list so that it does not contain any elements. At this time, you can use the clear() method of the ArrayList class to achieve this.

The clear() method is a member method in the ArrayList class, used to remove all elements in the array list to make it an empty list.

The following is a sample code that demonstrates how to use the clear() method of the ArrayList class to clear an array list.

import java.util.ArrayList;

public class ClearArrayListExample {
    public static void main(String[] args) {
        // 创建一个数组列表
        ArrayList<String> fruits = new ArrayList<>();
        
        // 添加一些水果到数组列表
        fruits.add("苹果");
        fruits.add("香蕉");
        fruits.add("橙子");
        fruits.add("葡萄");
        
        // 打印原来的数组列表
        System.out.println("原来的数组列表：" + fruits); // 输出：[苹果, 香蕉, 橙子, 葡萄]
        
        // 使用clear()方法清空数组列表
        fruits.clear();
        
        // 打印清空后的数组列表
        System.out.println("清空后的数组列表：" + fruits); // 输出：[]
    }
}

In the above example code, we first create an array list fruits and add some fruits to it. Then, we use the clear() method to clear the array list, and use the System.out.println() method to print the cleared array list.

Run the above code, we can see that the cleared array list in the output result is empty, that is, it does not contain any elements.

It should be noted that the clear() method only clears the elements in the array list, but does not release the memory space. If we need to release the memory space occupied by the array list, we can set it to null after clearing the array list so that the garbage collector can reclaim these memory spaces.

Summary:
This article introduces how to use the clear() method of the ArrayList class to clear the array list in Java. By calling the clear() method, we can easily remove all elements from the array list, making it an empty list. This method can be used when you need to clear an existing array list.

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