// Copyright 2006 The Apache Software Foundation
//
// 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.
import java.util.Arrays;
/**
* Combines multiple values to form a single composite key. MultiKey can often be used as an alternative to nested
* maps.
*/
public final class MultiKey
{
private static final int PRIME = 31;
private final Object[] values;
private final int hashCode;
/**
* Creates a new instance from the provided values. It is assumed that the values provided are good map keys
* themselves -- immutable, with proper implementations of equals() and hashCode().
*
* @param values
*/
public MultiKey(Object... values)
{
this.values = values;
hashCode = PRIME * Arrays.hashCode(this.values);
}
@Override
public int hashCode()
{
return hashCode;
}
@Override
public boolean equals(Object obj)
{
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
final MultiKey other = (MultiKey) obj;
return Arrays.equals(values, other.values);
}
@Override
public String toString()
{
StringBuilder builder = new StringBuilder("MultiKey[");
boolean first = true;
for (Object o : values)
{
if (!first)
builder.append(", ");
builder.append(o);
first = false;
}
builder.append("]");
return builder.toString();
}
}
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