There are two variants of contains() in Java.util.TreeMap, both are discussed in this article.
1. containskey(Object o) : It returns true if the map contains a mapping for the specified key.
Parameters: o : The key which will be tested whether present or not. Return Value: Returns true if there is a mapping for the given key. Exception: ClassCastException : This is thrown if the given key cannot be compared with the keys currently in the map. NullPointerException : This is thrown if the specified key is null.
// Java code to demonstrate the working// of containsKey() import java.io.*;import java.util.*; public class containsKey {public static void main(String[] args) { // Declaring the tree map of Integer and String TreeMap<Integer, String> treemap = new TreeMap<Integer, String>(); // assigning the values in the tree map // using put() treemap.put(2, "two"); treemap.put(7, "seven"); treemap.put(3, "three"); treemap.put(6, "six"); treemap.put(9, "nine"); // Use of containsKey // returns true if mapping for the number is present System.out.println(treemap.containsKey(6)); System.out.println(treemap.containsKey(4)); }} |
Output:
true false
2. containsValue(Object o) : It returns true if this map maps one or more keys to the specified value.
Parameters: o : This is the value whose presence in this map is to be tested. Return Value: Returns true if a mapping to this value exists else false. Exception: NA
// Java code to demonstrate the working// of containsValue() import java.io.*;import java.util.*; public class containsValue {public static void main(String[] args) { // Declaring the tree map of Integer and String TreeMap<Integer, String> treemap = new TreeMap<Integer, String>(); // assigning the values in the tree map // using put() treemap.put(2, "two"); treemap.put(7, "seven"); treemap.put(3, "three"); treemap.put(6, "six"); treemap.put(9, "nine"); // Use of containsValue // returns true if more than one keys are mapped System.out.println(treemap.containsValue("six")); System.out.println(treemap.containsValue("four")); }} |
Output:
true false
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