TMap.compute fixed and tested

This commit is contained in:
Sergey Kapralov 2016-08-25 11:13:08 +03:00
parent dc4a937262
commit ec2a52900e
2 changed files with 61 additions and 5 deletions

View File

@ -105,15 +105,14 @@ public interface TMap<K, V> {
V newValue = remappingFunction.apply(key, oldValue);
if (oldValue != null) {
if (newValue != null) {
return put(key, newValue);
put(key, newValue);
} else {
return remove(key);
remove(key);
}
} else if (newValue != null) {
return put(key, newValue);
} else {
return null;
put(key, newValue);
}
return newValue;
}
default V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {

View File

@ -693,6 +693,63 @@ public class HashtableTest {
}
}
@Test
public void test_computeUpdatesValueIfPresent() {
Hashtable<String, String> ht10 = new Hashtable<>();
for(int i = 0; i < 10; i++) {
ht10.put("Key" + i, "Val" + i);
}
String newVal = ht10.compute("Key5", (k,v) -> "changed");
assertEquals("changed", newVal);
assertEquals(10, ht10.size());
for(int i = 0; i < 10; i++) {
if(i == 5) {
assertEquals("Value was incorrectly changed", "changed", ht10.get("Key" + i));
} else {
assertEquals("Value was unexpectedly changed", "Val" + i, ht10.get("Key" + i));
}
}
}
@Test
public void test_computePutsNewEntryIfKeyIsAbsent() {
Hashtable<String, String> ht10 = new Hashtable<>();
for(int i = 0; i < 10; i++) {
ht10.put("Key" + i, "Val" + i);
}
String newVal = ht10.compute("absent key", (k,v) -> "added");
assertEquals("added", newVal);
assertEquals(11, ht10.size());
for(int i = 0; i < 10; i++) {
assertEquals("Value was unexpectedly changed", "Val" + i, ht10.get("Key" + i));
}
assertEquals("New value expected","added", ht10.get("absent key"));
}
@Test
public void test_computeRemovesEntryOnNullMapping() {
Hashtable<String, String> ht10 = new Hashtable<>();
for(int i = 0; i < 10; i++) {
ht10.put("Key" + i, "Val" + i);
}
String newVal = ht10.compute("Key5", (k,v) -> null);
assertEquals(null, newVal);
assertEquals(9, ht10.size());
for(int i = 0; i < 10; i++) {
if(i == 5) {
assertEquals("Value was unexpectedly present in map", null, ht10.get("Key" + i));
} else {
assertEquals("Value was unexpectedly changed", "Val" + i, ht10.get("Key" + i));
}
}
}
@SuppressWarnings("unchecked")
protected <K, V> Hashtable<K, V> hashtableClone(Hashtable<K, V> s) {
return (Hashtable<K, V>) s.clone();