1这两天在研究JDK1.6 HashMap的源码，看着链表比较有趣，就参照HashMap resize时的transfer方法写了一个链表翻转的Demo先看看输出的效果：entry:E1-key=E1-valueentry.next:E2-key=E2-value===================华丽的分隔线===================entry:E2-key=E2-valueentry.next:E1-key=E1-value
3反转链表的代码：void transfer(Entry[] src, Entry[] newTable) { for (int j = 0; j < src.length; j++) { Entry e = src[j]; if (e != null) { src[j] = null; do { Entry next = e.next; int i = 0; e.next = newTable[i]; newTable[i] = e; e = next; } while (e != null); } }}
5看看main方法public static void main(String[] args) { ReverseLinkedListDemo reverseLinkedListDemo = new ReverseLinkedListDemo(); Entry[] newTable = new Entry[1]; Entry E2 = new Entry(11, 'E2-key', 'E2-value', null); Entry E1 = new Entry(1, 'E1-key', 'E1-value', E2); Entry[] src = {E1}; reverseLinkedListDemo.printLinkedEntry(src); reverseLinkedListDemo.transfer(src, newTable); System.out.println('===================华丽的分隔线==================='); reverseLinkedListDemo.printLinkedEntry(newTable);}
6执行下，看看结果entry:E1-key=E1-valueentry.next:E2-key=E2-value===================华丽的分隔线===================entry:E2-key=E2-valueentry.next:E1-key=E1-value
7粘一下完整的代码：Code:package chapter4;import java.util.HashMap;import java.util.Map;public class ReverseLinkedListDemo { public static void main(String[] args) { ReverseLinkedListDemo reverseLinkedListDemo = new ReverseLinkedListDemo(); Entry[] newTable = new Entry[1]; Entry E2 = new Entry(11, 'E2-key', 'E2-value', null); Entry E1 = new Entry(1, 'E1-key', 'E1-value', E2); Entry[] src = {E1}; reverseLinkedListDemo.printLinkedEntry(src); reverseLinkedListDemo.transfer(src, newTable); System.out.println('===================华丽的分隔线==================='); reverseLinkedListDemo.printLinkedEntry(newTable); } private void printLinkedEntry(Entry[] newTable) { for (Entry entry : newTable) { System.out.println('entry:' + entry); if (entry != null && entry.next != null) { System.out.println('entry.next:' + entry.next); } } } /** * Transfers all entries from current table to newTable. */ void transfer(Entry[] src, Entry[] newTable) { for (int j = 0; j < src.length; j++) { Entry e = src[j]; if (e != null) { src[j] = null; do { Entry next = e.next; int i = 0; e.next = newTable[i]; newTable[i] = e; e = next; } while (e != null); } } } static class Entry implements Map.Entry { final K key; V value; Entry next; final int hash; /** * Creates new entry. */ Entry(int h, K k, V v, Entry n) { value = v; next = n; key = k; hash = h; } public final K getKey() { return key; } public final V getValue() { return value; } public final V setValue(V newValue) { V oldValue = value; value = newValue; return oldValue; } public final boolean equals(Object o) { if (!(o instanceof Map.Entry)) return false; Map.Entry e = (Map.Entry) o; Object k1 = getKey(); Object k2 = e.getKey(); if (k1 == k2 || (k1 != null && k1.equals(k2))) { Object v1 = getValue(); Object v2 = e.getValue(); if (v1 == v2 || (v1 != null && v1.equals(v2))) return true; } return false; } public final int hashCode() { return (key == null ? 0 : key.hashCode()) ^ (value == null ? 0 : value.hashCode()); } public final String toString() { return getKey() + '=' + getValue(); } /** * This method is invoked whenever the value in an entry is * overwritten by an invocation of put(k,v) for a key k that's already * in the HashMap. */ void recordAccess(HashMap m) { } /** * This method is invoked whenever the entry is * removed from the table. */ void recordRemoval(HashMap m) { } }}
