
org.cp.elements.data.struct.SimpleKeyValue Maven / Gradle / Ivy
/*
* Copyright 2016 Author or Authors.
*
* 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 org.cp.elements.data.struct;
import java.util.Map;
import java.util.Optional;
import org.cp.elements.lang.Assert;
import org.cp.elements.lang.ObjectUtils;
import org.cp.elements.lang.concurrent.ThreadSafe;
/**
* The {@link SimpleKeyValue} class is a Thread-safe data structure modeling both a key and a value mapped to the key.
*
* @author John Blum
* @see java.util.Map
* @see java.util.Map.Entry
* @see org.cp.elements.data.struct.KeyValue
* @since 1.0.0
*/
@ThreadSafe
@SuppressWarnings("unused")
public class SimpleKeyValue implements KeyValue {
/**
* Factory method used to construct a new instance of {@link SimpleKeyValue} initialized from the given {@link Map.Entry}.
*
* @param {@link Class type} of the key.
* @param {@link Class type} of the value.
* @param mapEntry {@link Map.Entry} used to construct and initialize an instance of {@link SimpleKeyValue}.
* @return a new instance of {@link SimpleKeyValue} initialized from the the given {@link Map.Entry}.
* @see #newKeyValue(Object, Object)
* @see java.util.Map.Entry
*/
public static SimpleKeyValue from(Map.Entry mapEntry) {
Assert.notNull(mapEntry, "Map.Entry is required");
return newKeyValue(mapEntry.getKey(), mapEntry.getValue());
}
/**
* Factory method used to construct a new instance of {@link SimpleKeyValue} initialized with the given {@code key}
* and no value.
*
* @param {@link Class type} of the key.
* @param {@link Class type} of the value.
* @param key key in the key/value mapping; must not be {@literal null}.
* @return a new instance of {@link SimpleKeyValue} initialized with the given {@code key} with no value.
* @throws IllegalArgumentException if {@code key} is {@literal null}.
* @see #SimpleKeyValue(Object)
*/
public static SimpleKeyValue newKeyValue(KEY key) {
return new SimpleKeyValue<>(key);
}
/**
* Factory method used to construct a new instance of {@link SimpleKeyValue} initialized with the given {@code key}
* and {@code value}.
*
* @param {@link Class type} of the key.
* @param {@link Class type} of the value.
* @param key key in the key/value mapping; must not be {@literal null}.
* @param value value in the key/value mapping; may be {@literal null}.
* @return a new instance of {@link SimpleKeyValue} initialized with the given {@code key} with no value.
* @throws IllegalArgumentException if {@code key} is {@literal null}.
* @see #SimpleKeyValue(Object, Object)
*/
public static SimpleKeyValue newKeyValue(KEY key, VALUE value) {
return new SimpleKeyValue<>(key, value);
}
private final KEY key;
private final VALUE value;
/**
* Constructs a new instance of {@link SimpleKeyValue} initialized with the given {@code key} and a {@literal null} value.
*
* @param key key in the key/value mapping; must not be {@literal null}.
* @throws IllegalArgumentException if {@code key} is {@literal null}.
* @see #SimpleKeyValue(Object, Object)
*/
public SimpleKeyValue(KEY key) {
this(key, null);
}
/**
* Constructs a new instance of {@link SimpleKeyValue} initialized with the given {@code key} and {@code value}.
*
* @param key key in the key/value mapping; must not be {@literal null}.
* @param value value in the key/value mapping; may be {@literal null}.
* @throws IllegalArgumentException if {@code key} is {@literal null}.
*/
public SimpleKeyValue(KEY key, VALUE value) {
Assert.notNull(key, "Key is required");
this.key = key;
this.value = value;
}
/**
* Determines whether the {@link #getKey() key} has a value.
*
* @return a boolean value indicating whether the {@link #getKey() key} has a value.
* @see #getValue(Object)
*/
public boolean isSet() {
return getValue(null) != null;
}
/**
* Return the key in the key/value mapping.
*
* @return the key.
*/
public KEY getKey() {
return this.key;
}
/**
* Return the value as a null-safe {@link Optional} value in the key/value mapping.
*
* @return the optional value.
* @see java.util.Optional
* @see #getValue(Object)
*/
public Optional getValue() {
return Optional.ofNullable(this.value);
}
/**
* Return the value in the key/value mapping.
*
* If the value is {@literal null}, then return the {@code defaulValue}.
*
* @param defaultValue default value to return if the value is {@literal null}.
* @return the value of the key/value mapping or {@code defaultValue} if value is {@literal null}.
* @see #getValue()
*/
public VALUE getValue(VALUE defaultValue) {
return getValue().orElse(defaultValue);
}
/**
* Determines whether this {@link SimpleKeyValue} is equal to the given {@link Object}.
*
* @param obj {@link Object} to compare for equality with this {@link SimpleKeyValue}.
* @return a boolean value indicating whether this {@link SimpleKeyValue} is equal to the given {@link Object}.
* @see java.lang.Object#equals(Object)
*/
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof SimpleKeyValue)) {
return false;
}
if (!getClass().equals(obj.getClass())) {
return false;
}
SimpleKeyValue, ?> that = (SimpleKeyValue, ?>) obj;
return this.getKey().equals(that.getKey())
&& ObjectUtils.equals(this.getValue(), that.getValue());
}
/**
* Computes the hash code for this {@link SimpleKeyValue}.
*
* @return an integer value containing the computed hash code of this {@link SimpleKeyValue}.
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
int hashValue = 17;
hashValue = 37 * hashValue + ObjectUtils.hashCode(getKey());
hashValue = 37 * hashValue + ObjectUtils.hashCode(getValue());
return hashValue;
}
/**
* Returns a {@link String} representation (view) of this {@link SimpleKeyValue}.
*
* @return a {@link String} describing this {@link SimpleKeyValue}.
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
return String.format("%1$s = %2$s", getKey(), getValue(null));
}
}
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