哈夫曼编码的java代码

以下是一个简单的 Java 实现哈夫曼编码的代码示例：

import java.util.PriorityQueue;
import java.util.Scanner;

public class HuffmanEncoder {

    static class HuffmanNode implements Comparable<HuffmanNode> {
        int frequency;
        char c;
        HuffmanNode left, right;

        public int compareTo(HuffmanNode hn) {
            return frequency - hn.frequency;
        }
    }

    public static void printCode(HuffmanNode root, String s) {
        if (root.left == null && root.right == null && Character.isLetter(root.c)) {
            System.out.println(root.c + ":" + s);
            return;
        }
        printCode(root.left, s + "0");
        printCode(root.right, s + "1");
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("请输入字符串: ");
        String str = sc.nextLine();
        int[] freq = new int[26];
        for (int i = 0; i < str.length(); i++) {
            freq[str.charAt(i) - 'a']++;
        }
        PriorityQueue<HuffmanNode> q = new PriorityQueue<>();
        for (char c = 'a'; c <= 'z'; c++) {
            if (freq[c - 'a'] > 0) {
                HuffmanNode hn = new HuffmanNode();
                hn.c = c;
                hn.frequency = freq[c - 'a'];
                hn.left = null;
                hn.right = null;
                q.add(hn);
            }
        }
        HuffmanNode root = null;
        while (q.size() > 1) {
            HuffmanNode x = q.peek();
            q.poll();
            HuffmanNode y = q.peek();
            q.poll();
            HuffmanNode f = new HuffmanNode();
            f.frequency = x.frequency + y.frequency;
            f.c = '-';
            f.left = x;
            f.right = y;
            root = f;
            q.add(f);
        }
        System.out.println("字符编码:");
        printCode(root, "");
    }
}

该代码首先读入一个字符串，然后计算每个字符出现的频率。接下来，使用优先队列实现了哈夫曼树的构建。最后，使用递归方法打印出每个字符的哈夫曼编码。