Use java's HashMap.values() function to get all the values ​​in the HashMap

Use Java's HashMap.values() function to obtain all values ​​in HashMap

In Java, HashMap is a commonly used data structure that can store key-value pairs and allows retrieval by key value. Sometimes, we need to get all the values ​​in the HashMap, then we can use the HashMap.values() function.

The HashMap.values() function returns a collection containing all values. This collection type is a subclass of the Collection class. We can use this collection to iterate through all values ​​in the HashMap or perform other operations. The following is a sample code:

import java.util.HashMap;
import java.util.Collection;

public class Main {
    public static void main(String[] args) {
        // 创建一个HashMap
        HashMap<Integer, String> hashMap = new HashMap<>();
        
        // 向HashMap中添加键值对
        hashMap.put(1, "Apple");
        hashMap.put(2, "Banana");
        hashMap.put(3, "Orange");
        hashMap.put(4, "Grapes");
        
        // 使用HashMap.values()函数获取所有值的集合
        Collection<String> values = hashMap.values();
        
        // 遍历值的集合并输出
        for (String value : values) {
            System.out.println("值: " + value);
        }
    }
}

The above code first creates a HashMap and adds four key-value pairs to it. Then, use the HashMap.values() function to get the set of all values. Finally, iterate through the collection of values ​​through a for loop and output each value.

Run the above code, the following results will be output:

值: Apple
值: Banana
值: Orange
值: Grapes

You can see that all the values ​​in the HashMap are obtained using the HashMap.values() function, and these values ​​are successfully output.

If we need to perform other operations on the values ​​in HashMap, we can also use this collection object. For example, we can use collection methods to count the number of occurrences of a value, find specific values, and so on.

It should be noted that the values ​​in HashMap are unordered and duplicate values ​​are allowed. Therefore, ordering and uniqueness are not guaranteed when iterating through a collection of values. If we need to follow a specific order or remove duplicate values, we can do it before traversing.

To sum up, using Java’s HashMap.values() function can easily obtain all the values ​​in the HashMap. We can perform operations by traversing a collection of values, such as output values, statistical value occurrences, etc. When using HashMap, remember to use the HashMap.values() function appropriately to obtain values ​​for better subsequent processing.

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