Usage of entry in java

The Entry interface in Java is part of the collection framework and represents the key-value pairs in the map. It allows access to keys and values, and modification of values. Mainly used to process collections based on key-value pairs, such as Map, providing benefits such as fast access, modified values, and customized comparisons. Its methods include getKey(), getValue(), and setValue(V).

Entry interface in Java

Entry interface is part of the Java collection framework, which represents a key in a map value pair. It provides access to keys and values ​​and allows modification of their values.

Purpose

The Entry interface is usually used to handle collections based on key-value pairs, such as Map and Dictionary. It provides the following benefits:

• Fast Access: It allows direct access to keys and values ​​without traversing the entire collection.
• Modify value: You can use the setValue() method to modify the value associated with the key.
• Custom comparison: You can use Comparator to implement the Entry interface to customize the comparison logic between key-value pairs.

Methods

Entry interface provides the following main methods:

• getKey():Return key .
• getValue(): Return value.
• setValue(V): Modify the value associated with the key.

Example

The following example shows how to use the Entry interface:

<code class="java">import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;

public class EntryExample {

    public static void main(String[] args) {
        Map<String, Integer> map = new HashMap<>();
        map.put("John", 25);
        map.put("Mary", 30);
        map.put("Bob", 35);

        Set<Entry<String, Integer>> entries = map.entrySet();

        for (Entry<String, Integer> entry : entries) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }

        // 修改值
        map.get("John").setValue(27);
        System.out.println(map.get("John"));
    }
}</code>

Output:

<code>John: 25
Mary: 30
Bob: 35
John: 27</code>

As you like See, the sample code uses the Entry interface to obtain a key-value pair and modify one of the values.

The above is the detailed content of Usage of entry in java. For more information, please follow other related articles on the PHP Chinese website!