霍夫曼代碼解釋Java

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我是新來的java，我想通過在線使用代碼來理解哈夫曼編碼。我搞亂了代碼來理解它是如何工作的，因爲我沒有發現如何實現霍夫曼代碼。我需要理解爲什麼在這段代碼中，這個人在霍夫曼樹類和字符串緩衝區中使用可比。如果有人知道在線霍夫曼編碼甚至算法的任何好解釋，請。我真的需要了解這段代碼。 PS：英語不是我的母語，所以很抱歉有任何混淆。謝謝霍夫曼代碼解釋Java

import java.util.*; 

public class HuffmanCode { 
    // input is an array of frequencies, indexed by character code 
    public HuffmanTree buildTree(int[] charFreqs) { 
     PriorityQueue<HuffmanTree> trees = new PriorityQueue<HuffmanTree>(); 
     // initially, we have a forest of leaves 
     // one for each non-empty character 
     for (int i = 0; i < charFreqs.length; i++) 
      if (charFreqs[i] > 0) 
       trees.offer(new HuffmanLeaf(charFreqs[i], (char)i)); 

     assert trees.size() > 0; 
     // loop until there is only one tree left 
     while (trees.size() > 1) { 
      // two trees with least frequency 
      HuffmanTree a = trees.poll(); 
      HuffmanTree b = trees.poll(); 

      // put into new node and re-insert into queue 
      trees.offer(new HuffmanNode(a, b)); 
     } 
     return trees.poll(); 
    } 

    public void printCodes(HuffmanTree tree, StringBuffer prefix) { 
     assert tree != null; 
     if (tree instanceof HuffmanLeaf) { 
      HuffmanLeaf leaf = (HuffmanLeaf)tree; 

      // print out character, frequency, and code for this leaf (which is just the prefix) 
      System.out.println(leaf.value + "\t" + leaf.frequency + "\t" + prefix); 

     } else if (tree instanceof HuffmanNode) { 
      HuffmanNode node = (HuffmanNode)tree; 

      // traverse left 
      prefix.append('0'); 
      //prefix = prefix + "0"; 
      printCodes(node.left, prefix); 
      prefix.deleteCharAt(prefix.length()-1); 

      // traverse right 
      prefix.append('1'); 
      printCodes(node.right, prefix); 
      prefix.deleteCharAt(prefix.length()-1); 
     } 
    } 
}

哈夫曼樹類：

public class HuffmanTree implements Comparable<HuffmanTree> { 
    public final int frequency; // the frequency of this tree 

    public HuffmanTree(int freq) { 
     frequency = freq; 
    } 

    // compares on the frequency 
    public int compareTo(HuffmanTree tree) { 
     return frequency - tree.frequency; 
    } 
}

霍夫曼葉：

class HuffmanLeaf extends HuffmanTree { 

    public final char value; // the character this leaf represents 

    public HuffmanLeaf(int freq, char val) { 
     super(freq); 
     value = val; 
    } 
}

霍夫曼節點：

class HuffmanNode extends HuffmanTree { 

    public final HuffmanTree left, right; // subtrees 

    public HuffmanNode(HuffmanTree l, HuffmanTree r) { 
     //Calling the super constructor HuffmanTree 
     super(l.frequency + r.frequency); 
     left = l; 
     right = r; 
    } 

}

主營：

public class Main { 

    public static void main(String[] args) { 
     String test = "Hello World"; 
     HuffmanCode newCode = new HuffmanCode(); 

     // we will assume that all our characters will have 
     // code less than 256, for simplicity 
     int[] charFreqs = new int[256]; 
     // read each character and record the frequencies 
     for (char c : test.toCharArray()) 
      charFreqs[c]++; 

     // build tree 
     ////HuffmanTree tree = buildTree(charFreqs); 
     HuffmanTree tree = newCode.buildTree(charFreqs); 

     // print out results 
     System.out.println("SYMBOL\tWEIGHT\tHUFFMAN CODE"); 
     newCode.printCodes(tree, new StringBuffer()); 
    } 

}

來源

2016-12-03 Knight Ramsamy

將打印語句添加到代碼或使用調試器並逐行運行，直到您認爲您明白 –

有人可以解釋我爲什麼這個人使用Stringbuffer和可比較的嗎？ –

不應該使用Stackoverflow作爲社區努力來理解您發現的一些隨機代碼，對不起。請嘗試運行代碼並找出它 –