In the previous article, we have discussed on how to remove an entry or entries from HashMap by comparing values using Java 8 APIs
Here, we will discuss how can we remove entry/entries from HashMap using Java 8 APIs by comparing keys
Remove entries using removeIf() method by comparing keys :
- removeIf() – Removes all of the elements of this collection that satisfy the given predicate
- Syntax: default boolean removeIf(Predicate filter);
- We will cover different cases to remove entry/entries using removeIf() method by comparing keys using Java 8 APIs
Let’s discuss removing entries from Map using different operators like =, >, <, etc.,
1. Remove an entry by comparing keys using Equal-To (=) operator
RemoveEntryFromHashMapByComparingKeys.java
package in.bench.resources.map.java8.example;
import java.util.HashMap;
import java.util.Map;
public class RemoveEntryFromHashMapByComparingKeys {
public static void main(String[] args) {
// create HashMap
Map<Integer, String> map = new HashMap<Integer, String>();
// put few items
map.put(1, "Google");
map.put(2, "YouTube");
map.put(3, "Facebook");
map.put(4, "Yahoo");
map.put(5, "Amazon");
map.put(6, "Reddit");
map.put(7, "Twitter");
// printing map before removeIf
System.out.println("Before removing entry from Map : \n" + map);
// removing an Entry using Java 1.8 (boolean equalTo expression)
map.entrySet().removeIf(
ranks -> ranks.getKey().compareTo(Integer.valueOf(4)) == 0);
// printing map after removeIf
System.out.println("\n\nAfter removing entry from Map : \n" + map);
}
}
Output:
Before removing entry from Map :
{1=Google, 2=YouTube, 3=Facebook, 4=Yahoo, 5=Amazon, 6=Reddit, 7=Twitter}
After removing entry from Map :
{1=Google, 2=YouTube, 3=Facebook, 5=Amazon, 6=Reddit, 7=Twitter}
2. Removing all entries by comparing keys using Greater-Than (>) operator
RemovingAllEntriesGreaterThanByComparingKeys.java
package in.bench.resources.map.java8.example;
import java.util.HashMap;
import java.util.Map;
public class RemovingAllEntriesGreaterThanByComparingKeys {
public static void main(String[] args) {
// create HashMap
Map<Integer, String> map = new HashMap<Integer, String>();
// put few items
map.put(1, "Google");
map.put(2, "YouTube");
map.put(3, "Facebook");
map.put(4, "Yahoo");
map.put(5, "Amazon");
map.put(6, "Reddit");
map.put(7, "Twitter");
// printing map before removeIf
System.out.println("Before removing entry from Map : \n" + map);
// removing all entries whose rank greater-than 5
map.entrySet().removeIf(
ranks -> ranks.getKey().compareTo(Integer.valueOf(5)) > 0);
// printing map after removeIf
System.out.println("\n\nAfter removing entry from Map : \n" + map);
}
}
Output:
Before removing entry from Map :
{1=Google, 2=YouTube, 3=Facebook, 4=Yahoo, 5=Amazon, 6=Reddit, 7=Twitter}
After removing entry from Map :
{1=Google, 2=YouTube, 3=Facebook, 4=Yahoo, 5=Amazon}
1.3 Removing all entries by comparing keys using Less-Than (<) operator
RemovingAllEntriesLessThanByComparingKeys.java
package in.bench.resources.map.java8.example;
import java.util.HashMap;
import java.util.Map;
public class RemovingAllEntriesLessThanByComparingKeys {
public static void main(String[] args) {
// create HashMap
Map<Integer, String> map = new HashMap<Integer, String>();
// put few items
map.put(1, "Google");
map.put(2, "YouTube");
map.put(3, "Facebook");
map.put(4, "Yahoo");
map.put(5, "Amazon");
map.put(6, "Reddit");
map.put(7, "Twitter");
// printing map before removeIf
System.out.println("Before removing entry from Map : \n" + map);
// removing all entries whose rank less-than 3
map.entrySet().removeIf(
ranks -> ranks.getKey().compareTo(Integer.valueOf(3)) < 0);
// printing map after removeIf
System.out.println("\n\nAfter removing entry from Map : \n" + map);
}
}
Output:
Before removing entry from Map :
{1=Google, 2=YouTube, 3=Facebook, 4=Yahoo, 5=Amazon, 6=Reddit, 7=Twitter}
After removing entry from Map :
{3=Facebook, 4=Yahoo, 5=Amazon, 6=Reddit, 7=Twitter}
In the next article, we will discuss how to remove entry/entries from HashMap by comparing values using Java 8 APIs
Related Articles:
- Java 8 – How to find duplicate and its count in a Stream or List ?
- Java 8 – How to remove duplicates from ArrayList
- Java 8 – How to remove duplicates from LinkedList
- Java 8 – How to find duplicate and its count in an Arrays ?
- Java 8 – How to remove duplicate from Arrays ?
- Java 8 – Various ways to remove duplicate elements from Arrays
- Java 8 – How to remove an entry from HashMap by comparing keys
- Java 8 – How to remove an entry from HashMap by comparing values
Hope, you found this article very helpful. If you have any suggestion or want to contribute any other way or tricky situation you faced during Interview hours, then share with us. We will include that code here.
Happy Coding !!
Happy Learning !!