Java程序来检查TreeMap中是否存在特定键
若要检查TreeMap中是否存在特定键，请使用containsKey()方法。
首先创建一个TreeMap并添加一些元素-
TreeMap<Integer,String> m = new TreeMap<Integer,String>(); m.put(1,"PHP"); m.put(2,"jQuery"); m.put(3,"JavaScript"); m.put(4,"Ruby"); m.put(5,"Java"); m.put(6,"AngularJS"); m.put(7,"ExpressJS");
现在，假设我们需要检查键5是否存在。为此，设置这样的containsKey()方法-
m.containsKey(5)
以下是检查TreeMap中是否存在特定键的示例-
示例
import java.util.*;
public class Demo {
public static void main(String args[]) {
TreeMap<Integer,String> m = new TreeMap<Integer,String>();
m.put(1,"PHP");
m.put(2,"jQuery");
m.put(3,"JavaScript");
m.put(4,"Ruby");
m.put(5,"Java");
m.put(6,"AngularJS");
m.put(7,"ExpressJS");
System.out.println("TreeMap Elements...\n"+m);
System.out.println("Does key 5 exist in the TreeMap = "+m.containsKey(5));
}
}输出结果
TreeMap Elements...
{1=PHP, 2=jQuery, 3=JavaScript, 4=Ruby, 5=Java, 6=AngularJS, 7=ExpressJS}
Does key 5 exist in the TreeMap = true