Mega Code Archive
Performs an xor on a set of booleans
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
/**
* Operations on boolean primitives and Boolean objects.
*
* This class tries to handle <code>null</code> input gracefully.
* An exception will not be thrown for a <code>null</code> input.
* Each method documents its behaviour in more detail.
*
* @author Stephen Colebourne
* @author Matthew Hawthorne
* @author Gary Gregory
* @since 2.0
* @version $Id: BooleanUtils.java 589050 2007-10-27 05:07:45Z bayard $
*/
public class Main {
/**
* Performs an xor on a set of booleans.
*
* <pre>
* BooleanUtils.xor(new boolean[] { true, true }) = false
* BooleanUtils.xor(new boolean[] { false, false }) = false
* BooleanUtils.xor(new boolean[] { true, false }) = true
* </pre>
*
* @param array an array of <code>boolean<code>s
* @return <code>true</code> if the xor is successful.
* @throws IllegalArgumentException if <code>array</code> is <code>null</code>
* @throws IllegalArgumentException if <code>array</code> is empty.
*/
public static boolean xor(boolean[] array) {
// Validates input
if (array == null) {
throw new IllegalArgumentException("The Array must not be null");
} else if (array.length == 0) {
throw new IllegalArgumentException("Array is empty");
}
// Loops through array, comparing each item
int trueCount = 0;
for (int i = 0; i < array.length; i++) {
// If item is true, and trueCount is < 1, increments count
// Else, xor fails
if (array[i]) {
if (trueCount < 1) {
trueCount++;
} else {
return false;
}
}
}
// Returns true if there was exactly 1 true item
return trueCount == 1;
}
/**
* Performs an xor on an array of Booleans.
*
* <pre>
* BooleanUtils.xor(new Boolean[] { Boolean.TRUE, Boolean.TRUE }) = Boolean.FALSE
* BooleanUtils.xor(new Boolean[] { Boolean.FALSE, Boolean.FALSE }) = Boolean.FALSE
* BooleanUtils.xor(new Boolean[] { Boolean.TRUE, Boolean.FALSE }) = Boolean.TRUE
* </pre>
*
* @param array an array of <code>Boolean<code>s
* @return <code>true</code> if the xor is successful.
* @throws IllegalArgumentException if <code>array</code> is <code>null</code>
* @throws IllegalArgumentException if <code>array</code> is empty.
* @throws IllegalArgumentException if <code>array</code> contains a <code>null</code>
*/
public static Boolean xor(Boolean[] array) {
if (array == null) {
throw new IllegalArgumentException("The Array must not be null");
} else if (array.length == 0) {
throw new IllegalArgumentException("Array is empty");
}
boolean[] primitive = null;
try {
primitive = toPrimitive(array);
} catch (NullPointerException ex) {
throw new IllegalArgumentException("The array must not contain any null elements");
}
return xor(primitive) ? Boolean.TRUE : Boolean.FALSE;
}
/**
* Converts an array of object Booleans to primitives.
*
* This method returns <code>null</code> for a <code>null</code> input array.
*
* @param array a <code>Boolean</code> array, may be <code>null</code>
* @return a <code>boolean</code> array, <code>null</code> if null array input
* @throws NullPointerException if array content is <code>null</code>
*/
public static boolean[] toPrimitive(Boolean[] array) {
if (array == null) {
return null;
} else if (array.length == 0) {
return new boolean[0];
}
final boolean[] result = new boolean[array.length];
for (int i = 0; i < array.length; i++) {
result[i] = array[i].booleanValue();
}
return result;
}
}
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