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This commit is contained in:
Seshu Thanneeru 2022-01-17 21:43:26 +05:30
parent f802d3d337
commit 6190f6801f
1 changed files with 16 additions and 14 deletions
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30
java-collections-maps-3/src/main/java/com/baeldung/map/identity/IdentityHashMapDemonstrator.java
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@ -22,7 +22,8 @@ public class IdentityHashMapDemonstrator {
IdentityHashMap<String, String> identityHashMap = new IdentityHashMap<>();
identityHashMap.put(null, "Null Key Accepted");
identityHashMap.put("Null Value Accepted", null);
System.out.println(identityHashMap);
assert ("Null Key Accepted" == identityHashMap.get(null));
assert (null == identityHashMap.get("Null Value Accepted"));
}
private static void iterateIdentityHashMap(IdentityHashMap<String, String> identityHashMap) {
@ -89,29 +90,30 @@ public class IdentityHashMapDemonstrator {
private static void demoMutableKeys() {
Book book1 = new Book("A Passage to India", 1924);
Book book2 = new Book("Invisible Man", 1953);
HashMap<Book, String> hashMap = new HashMap<>(10);
IdentityHashMap<Book, String> identityHashMap = new IdentityHashMap<>(10);
hashMap.put(book1, "A great work of fiction");
identityHashMap.put(book1, "A great work of fiction");
hashMap.put(book2, "won the US National Book Award");
identityHashMap.put(book2, "won the US National Book Award");
book2.year = 1952;
System.out.println("Book2 from HashMap: " + hashMap.get(book2));
System.out.println("Book2 from IdentityHashMap: " + identityHashMap.get(book2));
assert (null == hashMap.get(book2));
System.out.println("HashMap: " + hashMap);
IdentityHashMap<Book, String> identityHashMap = new IdentityHashMap<>(10);
identityHashMap.put(book1, "A great work of fiction");
identityHashMap.put(book2, "won the US National Book Award");
book2.year = 1951;
assert ("won the US National Book Award" == identityHashMap.get(book2));
System.out.println("IdentityHashMap: " + identityHashMap);
}
private static void demoHashMapVsIdentityMap(IdentityHashMap<String, String> identityHashMap) {
HashMap<String, String> hashMap = new HashMap<>(identityHashMap);
hashMap.put(new String("genre"), "Drama");
identityHashMap.put(new String("genre"), "Drama");
System.out.println("HashMap size: " + hashMap.size());
System.out.println("IdentityHashMap size: " + identityHashMap.size());
assert (4 == hashMap.size());
System.out.println("HashMap content: " + hashMap);
identityHashMap.put(new String("genre"), "Drama");
assert (5 == identityHashMap.size());
System.out.println("IdentityHashMap content: " + identityHashMap);
}
@ -127,8 +129,8 @@ public class IdentityHashMapDemonstrator {
private static void updateWithNewValue(IdentityHashMap<String, String> identityHashMap) {
String oldTitle = identityHashMap.put("title", "Harry Potter and the Deathly Hallows");
System.out.println("Old Title: " + oldTitle);
System.out.println("Updated Title: " + identityHashMap.get("title"));
assert ("Harry Potter and the Goblet of Fire" == oldTitle);
assert ("Harry Potter and the Deathly Hallows" == identityHashMap.get("title"));
}
public static void addValue(IdentityHashMap<String, String> identityHashMap, String key, String value) {