# Java 中的`TreeMap` > 原文： [https://beginnersbook.com/2013/12/treemap-in-java-with-example/](https://beginnersbook.com/2013/12/treemap-in-java-with-example/) `TreeMap`是基于紅黑樹的`NavigableMap`實現。它根據其鍵的自然順序排序。 `TreeMap`類**實現類似于`HashMap`類的`Map`接口。它們之間的主要區別在于[`HashMap`](https://beginnersbook.com/2013/12/hashmap-in-java-with-example/)是一個無序集合，而`TreeMap`按其鍵的升序排序。`TreeMap`是非同步的集合類，這意味著除非明確同步，否則它不適合線程安全操作。 ## `TreeMap`示例 在這個例子中，我們將鍵映射和值映射存儲到`TreeMap`中，并且我們在從`TreeMap`獲取數據時獲得排序的鍵值映射。 ```java import java.util.TreeMap; import java.util.Set; import java.util.Iterator; import java.util.Map; public class Details { public static void main(String args[]) { /* This is how to declare TreeMap */ TreeMap<Integer, String> tmap = new TreeMap<Integer, String>(); /*Adding elements to TreeMap*/ tmap.put(1, "Data1"); tmap.put(23, "Data2"); tmap.put(70, "Data3"); tmap.put(4, "Data4"); tmap.put(2, "Data5"); /* Display content using Iterator*/ Set set = tmap.entrySet(); Iterator iterator = set.iterator(); while(iterator.hasNext()) { Map.Entry mentry = (Map.Entry)iterator.next(); System.out.print("key is: "+ mentry.getKey() + " & Value is: "); System.out.println(mentry.getValue()); } } } ``` 輸出： ```java key is: 1 & Value is: Data1 key is: 2 & Value is: Data5 key is: 4 & Value is: Data4 key is: 23 & Value is: Data2 key is: 70 & Value is: Data3 ``` 正如您所看到的那樣，我們已經以隨機順序插入數據，但是當我們顯示`TreeMap`內容時，我們按照鍵的升序獲得了排序結果。 #### `TreeMap`教程 以下是`TreeMap`類上發布的教程列表： * [`TreeMap`示例](https://beginnersbook.com/2013/12/treemap-in-java-with-example/ "TreeMap in Java with Example") * [按值排序`TreeMap`](https://beginnersbook.com/2014/07/how-to-sort-a-treemap-by-value-in-java/ "How to sort a TreeMap by value in java") * [`TreeMap`迭代器示例](https://beginnersbook.com/2014/07/treemap-iterator-example-java/) * [以相反的順序迭代`TreeMap`](https://beginnersbook.com/2014/07/how-to-iterate-treemap-in-reverse-order-in-java/) * [從`TreeMap`獲取子映射](https://beginnersbook.com/2014/07/how-to-get-the-sub-map-from-treemap-example-java/) * [獲取`TreeMap`的大小](https://beginnersbook.com/2014/07/how-to-get-the-size-of-treemap-example-java/) * [從`TreeMap`中刪除鍵值映射](https://beginnersbook.com/2014/07/remove-key-value-mapping-from-treemap-example/) * [從`TreeMap`中刪除所有映射](https://beginnersbook.com/2014/07/remove-all-mappings-from-treemap-example-java/) #### 參考： * [`TreeMap`文檔](https://docs.oracle.com/javase/7/docs/api/java/util/TreeMap.html)