org.bonitasoft.engine.commons.NullCheckingUtil Maven / Gradle / Ivy
/**
* Copyright (C) 2015 BonitaSoft S.A.
* BonitaSoft, 32 rue Gustave Eiffel - 38000 Grenoble
* This library is free software; you can redistribute it and/or modify it under the terms
* of the GNU Lesser General Public License as published by the Free Software Foundation
* version 2.1 of the License.
* This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
* Floor, Boston, MA 02110-1301, USA.
**/
package org.bonitasoft.engine.commons;
import java.util.BitSet;
/**
* @author Elias Ricken de Medeiros
*/
public class NullCheckingUtil {
/**
* Check that the given parameters are not null.
* This method should only be used to check that some parameters given to a
* given method are not null. The exception message tries its best to produce
* a helpful message by scanning the stack trace.
*
* @param params
* the parameters to check
* @throws IllegalArgumentException
* if at least one of the parameters is null
*/
public static void checkArgsNotNull(final Object... params) {
checkArgsNotNull(1, params);
}
/**
* Check that the given parameters are not null.
* This method should only be used to check that some parameters given to a
* given method are not null. The exception message tries its best to produce
* a helpful message by scanning the stack trace.
*
* @param offset
* the offset to use in the stack trace to produce error message
* @param params
* the parameters to check
* @throws IllegalArgumentException
* if at least one of the parameters is null
*/
private static void checkArgsNotNull(final int offset, final Object... params) {
final NullCheckResult result = findNull(params);
if (result.hasNull()) {
// Guess the signature of the caller
final StackTraceElement callerSTE = getCaller(offset + 1);
final String className = callerSTE.getClassName();
final String methodName = callerSTE.getMethodName();
final StringBuilder sb = new StringBuilder();
for (int i = 0; i < result.getSize(); i++) {
if (result.isNull(i)) {
sb.append("null");
} else {
sb.append(params[i].getClass().getName());
}
if (i < result.getSize() - 1) {
sb.append(", ");
}
}
final StringBuilder messageStb = new StringBuilder("Some parameters are null in ");
messageStb.append(className);
messageStb.append('.');
messageStb.append(methodName);
messageStb.append("(): ");
messageStb.append(sb.toString());
throw new IllegalArgumentException(messageStb.toString());
}
}
/**
* Find null parameters in the given list.
* This method returns a {@link NullCheckResult}.
*
* @param params
* the parameters to check
* @return a {@link NullCheckResult} representing null parameters.
* @see NullCheckResult
*/
public static NullCheckResult findNull(final Object... params) {
if (params == null) {
final BitSet bitSet = new BitSet(1);
bitSet.set(0);
return new NullCheckResult(bitSet, 1);
}
final BitSet bitSet = new BitSet(params.length);
for (int i = 0; i < params.length; i++) {
bitSet.set(i, params[i] == null);
}
return new NullCheckResult(bitSet, params.length);
}
/**
* Return the StackTraceElement at the given offset from this method
* invocation.
*
* @param offset
* @return a StackTraceElement
*/
public static StackTraceElement getCaller(final int offset) {
final StackTraceElement[] stes = Thread.currentThread().getStackTrace();
StackTraceElement callerSTE = null;
for (int i = 0; i < stes.length - offset - 1; i++) {
if (stes[i].getClassName().equals(NullCheckingUtil.class.getName()) && stes[i].getMethodName().equals("getCaller")) {
callerSTE = stes[i + 1 + offset];
break;
}
}
badStateIfNull(callerSTE, "Ouch! Can't get the stack trace back to the caller of this method!");
return callerSTE;
}
/**
* This method throw an IllegalStateException if the given parameter is null
*
* @param valueToCheck
* the value to check
* @param msg
* the message for the thrown exception
* @see IllegalStateException
*/
public static void badStateIfNull(final Object valueToCheck, final String msg) {
badStateIfTrue(valueToCheck == null, msg);
}
/**
* This method throw an IllegalStateException if the given parameter is true
*
* @param valueToCheck
* the value to check
* @param msg
* the message for the thrown exception
* @see IllegalStateException
*/
public static void badStateIfTrue(final boolean valueToCheck, final String msg) {
if (valueToCheck) {
throw new IllegalStateException(msg);
}
}
/**
* Represents null value returned by {@link #findNull(Object...)}.
*
* @see #findNull(Object...)
*/
public static class NullCheckResult {
private final int size;
private final BitSet bitSet;
NullCheckResult(final BitSet bitSet, final int size) {
this.bitSet = bitSet;
this.size = size;
}
/**
* Returns true if some parameters given to {@link #findNull(Object...)} were null.
*
* @return true if some parameters given to {@link #findNull(Object...)} were null.
* @see #findNull(Object...)
*/
public boolean hasNull() {
return bitSet.cardinality() != 0;
}
/**
* Returns the number of parameters given to {@link #findNull(Object...)}
*
* @return the number of parameters given to {@link #findNull(Object...)}
* @see #findNull(Object...)
*/
public int getSize() {
return size;
}
/**
* Returns true if the i th parameter given to {@link #findNull(Object...)} was null.
*
* @param i
* the rank of the parameter given to {@link #findNull(Object...)}.
* @return true if the i th parameter given to {@link #findNull(Object...)} was null.
*/
public boolean isNull(final int i) {
return bitSet.get(i);
}
}
}