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BAEL-5162 : HashMap Entry Removal (#11276)

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priya-soni 2021-10-11 10:44:58 +05:30 committed by GitHub
parent 95fdf94aee
commit f95568145a
1 changed files with 74 additions and 0 deletions
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core-java-modules/core-java-collections-maps-3/src/main/java/com/baeldung/map/hashmap/entryremoval/RemoveEntryApplication.java Normal file
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package com.baeldung.map.hashmap.entryremoval;
import java.util.ConcurrentModificationException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
public class RemoveEntryApplication {
public static void main(String[] args) {
HashMap<String, String> foodItemTypeMap = new HashMap<>();
foodItemTypeMap.put("Apple", "Fruit");
foodItemTypeMap.put("Grape", "Fruit");
foodItemTypeMap.put("Mango", "Fruit");
foodItemTypeMap.put("Carrot", "Vegetable");
foodItemTypeMap.put("Potato", "Vegetable");
foodItemTypeMap.put("Spinach", "Vegetable");
// Current Map Status: {Potato=Vegetable, Apple=Fruit, Carrot=Vegetable, Grape=Fruit, Mango=Fruit, Spinach=Vegetable}
foodItemTypeMap.remove("Apple");
// Current Map Status: {Potato=Vegetable, Carrot=Vegetable, Grape=Fruit, Mango=Fruit, Spinach=Vegetable}
foodItemTypeMap.remove("Grape", "Vegetable");
// Current Map Status: {Potato=Vegetable, Carrot=Vegetable, Grape=Fruit, Mango=Fruit, Spinach=Vegetable}
try {
for (Entry<String, String> item : foodItemTypeMap.entrySet()) {
if (item.getKey()
.equals("Potato")) {
foodItemTypeMap.remove(item.getKey());
}
}
} catch (ConcurrentModificationException e) {
System.out.println("Exception occured while updating map: " + e.toString());
}
foodItemTypeMap.entrySet()
.removeIf(entry -> entry.getKey()
.equals("Grape"));
// Current Map Status: {Carrot=Vegetable, Mango=Fruit, Spinach=Vegetable}
Iterator<Entry<String, String>> iterator = foodItemTypeMap.entrySet()
.iterator();
while (iterator.hasNext()) {
if (iterator.next()
.getKey()
.equals("Carrot"))
iterator.remove();
}
// Current Map Status: {Mango=Fruit, Spinach=Vegetable}
// Use ConcurrentHashMap
ConcurrentHashMap<String, String> foodItemTypeConcMap = new ConcurrentHashMap<>();
foodItemTypeConcMap.put("Apple", "Fruit");
foodItemTypeConcMap.put("Grape", "Fruit");
foodItemTypeConcMap.put("Mango", "Fruit");
foodItemTypeConcMap.put("Carrot", "Vegetable");
foodItemTypeConcMap.put("Potato", "Vegetable");
foodItemTypeConcMap.put("Spinach", "Vegetable");
for (Entry<String, String> item : foodItemTypeConcMap.entrySet()) {
if (item.getKey() != null && item.getKey()
.equals("Potato")) {
foodItemTypeConcMap.remove(item.getKey());
}
}
// foodItemTypeConcMap : {Apple=Fruit, Carrot=Vegetable, Grape=Fruit, Mango=Fruit, Spinach=Vegetable}
}
}