TreeMap类实现类似于HashMap的Map接口。 TreeMap
是SortedMap的一个示例,即可以对键的顺序进行排序。
在下面的例子中,我们将展示TreeMap类的各种方法。如下:
put()
- 将键和值添加到Map中。get()
- 通过传递键返回值。remove()
- 从Map中删除键和值。size()
- 返回Map的大小。containsKey()
- 如果key存在于Map中则返回true,否则返回false。containsValue()
- 如果Map中存在value则返回true,否则返回false。clear()
- 从Map中删除所有元素。
文件:TreeMapExample.java -
package com.yiibai.tutorial;
import java.util.Map;
import java.util.TreeMap;
/**
* @author yiibai
*
*/
public class TreeMapExample {
public static void main(String[] args) {
Map<String String> map=new TreeMap<>();
/*Adding key and values in TreeMap*/
map.put("1" "One");
map.put("2" "Two");
map.put("3""Three");
map.put("4" "Four");
map.put("5" "Five");
System.out.println("TreeMap key-values:"+map);
/*Get value by key from the TreeMap*/
System.out.println("Value of '4' is: "+map.get("4"));
/*Removing key and value from the TreeMap */
map.remove("4");
System.out.println("After removal TreeMap Key-Value: " +map);
/*Getting size of TreeMap*/
System.out.println("Size of TreeMap is : "+map.size());
/*Checking if key exist in the TreeMap or not*/
System.out.println("Key '3' exist: "+map.containsKey("3"));
/*Checking if value exist in the TreeMap or not*/
System.out.println("Key '6' exist: "+map.containsValue("6"));
/*Remove all keys and values from the TreeMap*/
map.clear();
System.out.println("After clearing map: "+map);
}
}
执行上面示例代码,得到以下结果:
TreeMap key-values:{1=One 2=Two 3=Three 4=Four 5=Five}
Value of '4' is: Four
After removal TreeMap Key-Value: {1=One 2=Two 3=Three 5=Five}
Size of TreeMap is : 4
Key '3' exist: true
Key '6' exist: false
After clearing map: {}