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support library for libGDX
/** Copyright 2014 Robin Stumm ([email protected], http://dermetfan.net)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License. */
package net.dermetfan.utils;
/** @param the type of the key
* @param the type of the value
* @author dermetfan */
public class Pair {
/** the key */
private K key;
/** the value */
private V value;
/** creates an empty pair ({@link #key} and {@link #value} are {@code null}) */
public Pair() {}
/** @param key the {@link #key}
* @param value the {@link #value} */
public Pair(K key, V value) {
this.key = key;
this.value = value;
}
/** @param pair the {@link Pair} to copy */
public Pair(Pair pair) {
key = pair.key;
value = pair.value;
}
/** @param pair the Pair which {@link #key} and {@link #value} to use
* @return this Pair for chaining */
public Pair set(Pair pair) {
key = pair.key;
value = pair.value;
return this;
}
/** @param key the {@link #key} to set
* @param value the {@link #value} to set
* @return this Pair for chaining */
public Pair set(K key, V value) {
this.key = key;
this.value = value;
return this;
}
/** sets {@link #key} and {@link #value} to null */
public void clear() {
key = null;
value = null;
}
/** sets {@link #key} null */
public void clearKey() {
key = null;
}
/** sets {@link #value} null */
public void clearValue() {
value = null;
}
/** @return if {@link #key} or {@link #value} is not {@code null} */
public boolean isEmpty() {
return key == null && value == null;
}
/** @return if {@link #key} and {@link #value} are both not {@code null} */
public boolean isFull() {
return key != null && value != null;
}
/** @return if {@link #key} is not null */
public boolean hasKey() {
return key != null;
}
/** @return if {@link #value} is not null */
public boolean hasValue() {
return value != null;
}
/** swaps key and value
* @throws IllegalStateException if the classes of {@link #key} and {@link #value} are not {@link Class#isAssignableFrom(Class) assignable} from each other */
@SuppressWarnings("unchecked")
public void swap() throws IllegalStateException {
if(key.getClass() != value.getClass())
throw new IllegalStateException("key and value are not of the same type: " + key.getClass() + " & " + value.getClass());
V oldValue = value;
value = (V) key;
key = (K) oldValue;
}
@Override
public int hashCode() {
int result = key != null ? key.hashCode() : 0;
result = 31 * result + (value != null ? value.hashCode() : 0);
return result;
}
/** if the given object is a {@link Pair} instance, {@link Object#equals(Object) equals} comparison will be used on key and value */
@Override
public boolean equals(Object obj) {
if(obj instanceof Pair) {
Pair pair = (Pair) obj;
return key.equals(pair.key) && value.equals(pair.value);
}
return super.equals(obj);
}
/** @return [{@link #key} & {@link #value}] */
@Override
public String toString() {
return "[" + key + " & " + value + ']';
}
// getters and setters
/** @return the {@link #key} */
public K getKey() {
return key;
}
/** @param key the {@link #key} to set */
public void setKey(K key) {
this.key = key;
}
/** @return the {@link #value} */
public V getValue() {
return value;
}
/** @param value the {@link #value} to set */
public void setValue(V value) {
this.value = value;
}
}