Use the isEmpty() method of the HashSet class to determine whether a collection in Java is empty

Use the isEmpty() method of the HashSet class to determine whether the collection in Java is empty

HashSet is one of the commonly used collection classes in Java. It inherits the AbstractSet class and implements the Set interface. The elements stored in a HashSet are not repeated and are arranged in an unordered manner. In the process of using HashSet, sometimes we need to determine whether the set is empty. In this article, we will discuss how to use the isEmpty() method of HashSet to determine whether the set is empty.

The isEmpty() method is a member method in the HashSet class. The function of this method is to determine whether the HashSet is empty, that is, to determine whether there are any elements in the HashSet. The use of the isEmpty() method is very simple. You only need to call this method and return a boolean value. When the HashSet is empty, it returns true and when it is not empty, it returns false.

Next we use a simple example to demonstrate how to use the isEmpty() method to determine whether a HashSet is empty.

import java.util.HashSet;

public class HashSetExample {
    public static void main(String[] args) {
        // 创建一个空的HashSet
        HashSet<String> set1 = new HashSet<>();

        // 判断HashSet是否为空
        boolean isEmpty1 = set1.isEmpty();
        System.out.println("HashSet1是否为空：" + isEmpty1);

        // 添加元素到HashSet中
        set1.add("Apple");
        set1.add("Banana");
        set1.add("Orange");

        // 判断HashSet是否为空
        boolean isEmpty2 = set1.isEmpty();
        System.out.println("HashSet1是否为空：" + isEmpty2);

        // 创建一个非空的HashSet
        HashSet<Integer> set2 = new HashSet<>();
        set2.add(1);
        set2.add(2);
        set2.add(3);

        // 判断HashSet是否为空
        boolean isEmpty3 = set2.isEmpty();
        System.out.println("HashSet2是否为空：" + isEmpty3);
    }
}

Run the above code, you will get the following output result:

HashSet1是否为空：true
HashSet1是否为空：false
HashSet2是否为空：false

It can be seen from the output result that when it is first judged whether the empty set set1 is empty, the output is true, indicating that The set is empty; after adding elements to set1, it is judged again and the output is false, indicating that the set is not empty. Elements were added to set2 at the beginning, so the judgment result is false, indicating that the set is not empty.

Using the isEmpty() method can quickly and easily determine whether the HashSet is empty. When writing code, you can perform corresponding processing based on the judgment results to improve the simplicity and readability of the code.

Summary:
In this article we introduce how to use the isEmpty() method of the HashSet class to determine whether a collection in Java is empty. By calling the isEmpty() method, you can quickly determine whether the collection is empty and return a boolean value. Returns true when the collection is empty and false when it is not empty. In the actual programming process, using the isEmpty() method can improve the simplicity and readability of the code and facilitate the next step of processing. I hope this article can help you understand the isEmpty() method of the HashSet class.

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