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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