Java Dictionary Sorting: Using TreeMap

There is no direct way to sort a dictionary in Java, but you can achieve dictionary sorting by using a TreeMap. TreeMap is an ordered mapping based on a red-black tree, allowing for sorting based on the natural order of keys or a custom order.

Here is an example code demonstrating how to use TreeMap for dictionary sorting:

import java.util.TreeMap;

public class DictionarySort {
    public static void main(String[] args) {
        TreeMap<String, Integer> map = new TreeMap<>();
        
        // 添加元素到map
        map.put("apple", 5);
        map.put("banana", 2);
        map.put("orange", 3);
        map.put("grape", 4);
        
        // 字典排序
        for (String key : map.keySet()) {
            System.out.println(key + ": " + map.get(key));
        }
    }
}

Running the above code will result in:

apple: 5
banana: 2
grape: 4
orange: 3

In the example above, TreeMap was used to sort keys, resulting in pairs of key-value sorted in dictionary order. If a custom sorting rule is needed, a Comparator object can be passed in when creating the TreeMap object.