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bengi - guava map

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This commit is contained in:
Slavisa Avramovic 2016-06-09 15:00:56 +02:00
parent 635a5aa5ea
commit 8525795755
2 changed files with 112 additions and 114 deletions
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136
guava/src/test/java/org/baeldung/guava/GuavaMapFromSet.java
View File

@ -11,91 +11,91 @@ import com.google.common.base.Function;
public class GuavaMapFromSet<K, V> extends AbstractMap<K, V> { public class GuavaMapFromSet<K, V> extends AbstractMap<K, V> {
private class SingleEntry implements Entry<K, V> { private class SingleEntry implements Entry<K, V> {
private K key; private K key;
public SingleEntry( K key) { public SingleEntry(K key) {
this.key = key; this.key = key;
} }
@Override @Override
public K getKey() { public K getKey() {
return this.key; return this.key;
} }
@Override @Override
public V getValue() { public V getValue() {
V value = GuavaMapFromSet.this.cache.get(this.key); V value = GuavaMapFromSet.this.cache.get(this.key);
if (value == null) { if (value == null) {
value = GuavaMapFromSet.this.function.apply(this.key); value = GuavaMapFromSet.this.function.apply(this.key);
GuavaMapFromSet.this.cache.put(this.key, value); GuavaMapFromSet.this.cache.put(this.key, value);
} }
return value; return value;
} }
@Override @Override
public V setValue( V value) { public V setValue(V value) {
throw new UnsupportedOperationException(); throw new UnsupportedOperationException();
} }
} }
private class MyEntrySet extends AbstractSet<Entry<K, V>> { private class MyEntrySet extends AbstractSet<Entry<K, V>> {
public class EntryIterator implements Iterator<Entry<K, V>> { public class EntryIterator implements Iterator<Entry<K, V>> {
private Iterator<K> inner; private Iterator<K> inner;
public EntryIterator() { public EntryIterator() {
this.inner = MyEntrySet.this.keys.iterator(); this.inner = MyEntrySet.this.keys.iterator();
} }
@Override @Override
public boolean hasNext() { public boolean hasNext() {
return this.inner.hasNext(); return this.inner.hasNext();
} }
@Override @Override
public Map.Entry<K, V> next() { public Map.Entry<K, V> next() {
K key = this.inner.next(); K key = this.inner.next();
return new SingleEntry(key); return new SingleEntry(key);
} }
@Override @Override
public void remove() { public void remove() {
throw new UnsupportedOperationException(); throw new UnsupportedOperationException();
} }
} }
private Set<K> keys; private Set<K> keys;
public MyEntrySet( Set<K> keys) { public MyEntrySet(Set<K> keys) {
this.keys = keys; this.keys = keys;
} }
@Override @Override
public Iterator<Map.Entry<K, V>> iterator() { public Iterator<Map.Entry<K, V>> iterator() {
return new EntryIterator(); return new EntryIterator();
} }
@Override @Override
public int size() { public int size() {
return this.keys.size(); return this.keys.size();
} }
} }
private WeakHashMap<K, V> cache; private WeakHashMap<K, V> cache;
private Set<Entry<K, V>> entries; private Set<Entry<K, V>> entries;
private Function<? super K, ? extends V> function; private Function<? super K, ? extends V> function;
public GuavaMapFromSet( Set<K> keys, Function<? super K, ? extends V> function) { public GuavaMapFromSet(Set<K> keys, Function<? super K, ? extends V> function) {
this.function = function; this.function = function;
this.cache = new WeakHashMap<K, V>(); this.cache = new WeakHashMap<K, V>();
this.entries = new MyEntrySet(keys); this.entries = new MyEntrySet(keys);
} }
@Override @Override
public Set<Map.Entry<K, V>> entrySet() { public Set<Map.Entry<K, V>> entrySet() {
return this.entries; return this.entries;
} }
} }

90
guava/src/test/java/org/baeldung/guava/GuavaMapFromSetTests.java
View File

@ -13,54 +13,52 @@ import com.google.common.base.Function;
public class GuavaMapFromSetTests { public class GuavaMapFromSetTests {
@Test @Test
public void givenStringSet_whenMapsToElementLength_thenCorrect() { public void givenStringSet_whenMapsToElementLength_thenCorrect() {
Function<Integer, String> function = new Function<Integer, String>() { Function<Integer, String> function = new Function<Integer, String>() {
@Override
public String apply(Integer from) {
return Integer.toBinaryString(from);
}
};
Set<Integer> set = new TreeSet<>(Arrays.asList(32, 64, 128));
Map<Integer, String> map = new GuavaMapFromSet<Integer, String>(set, function);
assertTrue(map.get(32).equals("100000")
&& map.get(64).equals("1000000")
&& map.get(128).equals("10000000"));
}
@Override @Test
public String apply(Integer from) { public void givenIntSet_whenMapsToElementBinaryValue_thenCorrect() {
return Integer.toBinaryString(from.intValue()); Function<String, Integer> function = new Function<String, Integer>() {
}
};
Set<Integer> set = (Set<Integer>) new TreeSet<Integer>(Arrays.asList(
32, 64, 128));
Map<Integer, String> map = new GuavaMapFromSet<Integer, String>(set,
function);
assertTrue(map.get(32).equals("100000")
&& map.get(64).equals("1000000")
&& map.get(128).equals("10000000"));
}
@Test @Override
public void givenIntSet_whenMapsToElementBinaryValue_thenCorrect() { public Integer apply(String from) {
Function<String, Integer> function = new Function<String, Integer>() { return from.length();
}
};
Set<String> set = new TreeSet<>(Arrays.asList(
"four", "three", "twelve"));
Map<String, Integer> map = new GuavaMapFromSet<String, Integer>(set,
function);
assertTrue(map.get("four") == 4 && map.get("three") == 5
&& map.get("twelve") == 6);
}
@Override @Test
public Integer apply(String from) { public void givenSet_whenNewSetElementAddedAndMappedLive_thenCorrect() {
return from.length(); Function<String, Integer> function = new Function<String, Integer>() {
}
};
Set<String> set = (Set<String>) new TreeSet<String>(Arrays.asList(
"four", "three", "twelve"));
Map<String, Integer> map = new GuavaMapFromSet<String, Integer>(set,
function);
assertTrue(map.get("four") == 4 && map.get("three") == 5
&& map.get("twelve") == 6);
}
@Test
public void givenSet_whenNewSetElementAddedAndMappedLive_thenCorrect() {
Function<String, Integer> function = new Function<String, Integer>() {
@Override @Override
public Integer apply(String from) { public Integer apply(String from) {
return from.length(); return from.length();
} }
}; };
Set<String> set = (Set<String>) new TreeSet<String>(Arrays.asList( Set<String> set = new TreeSet<>(Arrays.asList(
"four", "three", "twelve")); "four", "three", "twelve"));
Map<String, Integer> map = new GuavaMapFromSet<String, Integer>(set, Map<String, Integer> map = new GuavaMapFromSet<String, Integer>(set,
function); function);
set.add("one"); set.add("one");
assertTrue(map.get("one") == 3 && map.size()==4); assertTrue(map.get("one") == 3 && map.size() == 4);
} }
} }