check if map contains key java
if (map.containsKey(key)) {
// Okay, there's a key but the value is null
} else {
// Definitely no such key
}check if map contains key java
if (map.containsKey(key)) {
// Okay, there's a key but the value is null
} else {
// Definitely no such key
}TreeMap containsKey() method in java
import java.util.TreeMap;
public class TreeMapContainsKeyMethodExample
{
public static void main(String[] args)
{
TreeMap<Integer, String> tm = new TreeMap<Integer, String>();
// map String values to Integer keys
tm.put(56, "orange");
tm.put(62, "indigo");
tm.put(43, "red");
tm.put(91, "green");
tm.put(38, "yellow");
System.out.println("TreeMap before using containsKey() method: " + tm);
// check for key element '62'
System.out.println("Does key '62' present? " + tm.containsKey(62));
// check for key element '90'
System.out.println("Does key '90' present? " + tm.containsKey(90));
}
}if hashmap contains only one key then how to get that key
HashMap<Node, Integer> x = qu.remove();
// This "qu" is a queue which is returning a Hashmap
// of type HashMap<Node, Integer> this hashmap contains
// only one key,value pair
Node node = x.keySet().iterator().next();
// here we are extracting that "KEY" of hashMap into variable of Node typeCopyright © 2021 Codeinu
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