com.google.gwt.dev.util.StringKey Maven / Gradle / Ivy
/*
* Copyright 2009 Google Inc.
*
* 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 com.google.gwt.dev.util;
import java.io.Serializable;
/**
* A "typed string" utility class that improves the readability of generic code
* by using proper types. Equality and comparison are implemented by using both
* the concrete type and string value.
*/
public abstract class StringKey implements Comparable, Serializable {
/**
* The hashcode is computed and stored since this type is expected to be used
* as a map key.
*/
private final int hashCode;
private final String value;
/**
* Constructor. A null value is legal.
*
* @param value the value this key object represents
*/
protected StringKey(String value) {
this.value = value;
this.hashCode = getClass().getName().hashCode() * 13
+ (value == null ? 0 : value.hashCode());
}
/**
* Compares based on concrete type name and then value.
*/
public final int compareTo(StringKey o) {
if (getClass() == o.getClass()) {
if (value == null) {
return o.value == null ? 0 : -1;
} else if (o.value == null) {
return value == null ? 0 : 1;
} else {
return value.compareTo(o.value);
}
}
return getClass().getName().compareTo(o.getClass().getName());
}
/**
* Delegates to {@link #compareTo}.
*/
@Override
public final boolean equals(Object o) {
if (o == null) {
return false;
}
return compareTo((StringKey) o) == 0 ? true : false;
}
/**
* Returns the value of the StringKey.
*/
public final String get() {
return value;
}
@Override
public final int hashCode() {
return hashCode;
}
/**
* Delegates to {@link #get()}.
*/
@Override
public String toString() {
return value;
}
}