/*
* 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.ngrinder.common.util;
import org.apache.commons.lang.StringUtils;
import org.picocontainer.annotations.Nullable;
import java.net.URL;
/**
* Simple static methods to be called at the start of your own methods to verify correct arguments and state. This
* allows constructs such as
*
* <pre>
* if (count <= 0) {
* throw new IllegalArgumentException("must be positive: " + count);
* }
* </pre>
*
* to be replaced with the more compact
*
* <pre>
* checkArgument(count > 0, "must be positive: %s", count);
* </pre>
*
* Note that the sense of the expression is inverted; with {@code Preconditions} you declare what you expect to be
* <i>true</i>, just as you do with an <a href="http://java.sun.com/j2se/1.5.0/docs/guide/language/assert.html">
* {@code assert}</a> or a JUnit {@code assertTrue} call.
*
* <p>
* <b>Warning:</b> only the {@code "%s"} specifier is recognized as a placeholder in these messages, not the full range
* of {@link String#format(String, Object[])} specifiers.
*
* <p>
* Take care not to confuse precondition checking with other similar types of checks! Precondition exceptions --
* including those provided here, but also {@link IndexOutOfBoundsException}, {@link UnsupportedOperationException} and
* others -- are used to signal that the <i>calling method</i> has made an error. This tells the caller that it should
* not have invoked the method when it did, with the arguments it did, or perhaps ever. Postcondition or other
* invariant
* failures should not throw these types of exceptions.
*
* @author Kevin Bourrillion
* @author JunHo Yoon (modify some.. add string related)
* @since 2 (imported from Google Collections Library)
*/
@SuppressWarnings("UnusedDeclaration")
public final class Preconditions {
private static final int DEFAULT_16 = 16;
private Preconditions() {
}
/**
* Ensures the truth of an expression involving one or more parameters to the calling method.
*
* @param expression a boolean expression
*/
public static void checkArgument(boolean expression) {
if (!expression) {
throw new IllegalArgumentException();
}
}
/**
* Ensures the truth of an expression involving one or more parameters to the calling method.
*
* @param expression a boolean expression
* @param errorMessage the exception message to use if the check fails; will be converted to a string using
* {@link String#valueOf(Object)}
*/
public static void checkArgument(boolean expression, @Nullable Object errorMessage) {
if (!expression) {
throw new IllegalArgumentException(String.valueOf(errorMessage));
}
}
/**
* Ensures the truth of an expression involving one or more parameters to the calling method.
*
* @param expression a boolean expression
* @param errorMessageTemplate a template for the exception message should the check fail. The message is formed by
* replacing each
* {@code %s} placeholder in the template with an argument. These are matched by position
* -
* the first
* {@code %s} gets {@code errorMessageArgs[0]}, etc. Unmatched arguments will be appended
* to the
* formatted message in square braces. Unmatched placeholders will be left as-is.
* @param errorMessageArgs the arguments to be substituted into the message template. Arguments are converted to
* strings using
* {@link String#valueOf(Object)}.
*/
public static void checkArgument(boolean expression, @Nullable String errorMessageTemplate,
@Nullable Object... errorMessageArgs) {
if (!expression) {
throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
}
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null and also not empty.
*
* @param <T> type
* @param expression array
* @param errorMessageTemplate error message
* @param errorMessageArgs args
* @return the non-null reference and the non-empty value that was validated
*/
public static <T> T[] checkNotEmpty(T[] expression, @Nullable String errorMessageTemplate,
@Nullable Object... errorMessageArgs) {
if (expression == null || expression.length == 0) {
throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
}
return expression;
}
/**
* Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters
* to the calling method.
*
* @param expression a boolean expression
*/
public static void checkState(boolean expression) {
if (!expression) {
throw new IllegalStateException();
}
}
/**
* Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters
* to the calling method.
*
* @param expression a boolean expression
* @param errorMessage the exception message to use if the check fails; will be converted to a string using
* {@link String#valueOf(Object)}
*/
public static void checkState(boolean expression, @Nullable Object errorMessage) {
if (!expression) {
throw new IllegalStateException(String.valueOf(errorMessage));
}
}
/**
* Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters
* to the calling method.
*
* @param expression a boolean expression
* @param errorMessageTemplate a template for the exception message should the check fail. The message is formed by
* replacing each
* {@code %s} placeholder in the template with an argument. These are matched by position
* -
* the first
* {@code %s} gets {@code errorMessageArgs[0]}, etc. Unmatched arguments will be appended
* to the
* formatted message in square braces. Unmatched placeholders will be left as-is.
* @param errorMessageArgs the arguments to be substituted into the message template. Arguments are converted to
* strings using
* {@link String#valueOf(Object)}.
*/
public static void checkState(boolean expression, @Nullable String errorMessageTemplate,
@Nullable Object... errorMessageArgs) {
if (!expression) {
throw new IllegalStateException(format(errorMessageTemplate, errorMessageArgs));
}
}
// Added By JunHo Yoon
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
* @return the non-null reference that was validated
*/
public static String checkNotEmpty(String reference) {
if (StringUtils.isEmpty(reference)) {
throw new IllegalArgumentException();
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
* @param errorMsg error message
* @return the non-null reference that was validated
*/
public static String checkNotEmpty(String reference, String errorMsg) {
if (StringUtils.isEmpty(reference)) {
throw new IllegalArgumentException(errorMsg);
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not 0.
*
* @param reference an object reference
* @param errorMsg error message
* @return the non-null reference that was validated
*/
public static Integer checkNotZero(Integer reference, String errorMsg) {
if (reference == null || reference == 0) {
throw new IllegalArgumentException(errorMsg);
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not 0.
*
* @param reference an object reference
* @param errorMsg error messgae.
* @return the non-null reference that was validated
*/
public static Long checkNotZero(Long reference, String errorMsg) {
if (reference == null || reference == 0L) {
throw new IllegalArgumentException(errorMsg);
}
return reference;
}
/**
* Ensures that an condition passed as a parameter is true.
*
* @param condition condition
* @param errorMsg error message
*/
public static void checkTrue(boolean condition, String errorMsg) {
if (!condition) {
throw new IllegalArgumentException(errorMsg);
}
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param <T> type
* @param reference reference
* @param message error message template
* @param args error formatting element
* @return the non-null reference that was validated
*/
public static <T> T checkExist(T reference, String message, Object... args) {
if (reference == null) {
throw new IllegalArgumentException(String.format(message, args));
}
return reference;
}
/**
* Ensures that the given reference is null.
*
* @param reference reference
* @param errorMessageTemplate error message template
* @param errorMessageArgs arguments to be filled in the template.
*/
public static <T> T checkNull(T reference, String errorMessageTemplate, Object... errorMessageArgs) {
if (reference != null) {
// If either of these parameters is null, the right thing happens anyway
throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param <T> type
* @param reference an object reference
* @return the non-null reference that was validated
*/
public static <T> T checkNotNull(T reference) {
if (reference == null) {
throw new IllegalArgumentException();
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param <T> type
* @param reference an object reference
* @param errorMessage the exception message to use if the check fails; will be converted to a string using
* {@link String#valueOf(Object)}
* @return the non-null reference that was validated
*/
public static <T> T checkNotNull(T reference, @Nullable Object errorMessage) {
if (reference == null) {
throw new IllegalArgumentException(String.valueOf(errorMessage));
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param <T> type
* @param reference an object reference
* @param errorMessageTemplate a template for the exception message should the check fail. The message is formed by
* replacing each
* {@code %s} placeholder in the template with an argument. These are matched by position
* -
* the first
* {@code %s} gets {@code errorMessageArgs[0]}, etc. Unmatched arguments will be appended
* to the
* formatted message in square braces. Unmatched placeholders will be left as-is.
* @param errorMessageArgs the arguments to be substituted into the message template. Arguments are converted to
* strings using
* {@link String#valueOf(Object)}.
* @return the non-null reference that was validated
*/
public static <T> T checkNotNull(T reference, @Nullable String errorMessageTemplate,
@Nullable Object... errorMessageArgs) {
if (reference == null) {
// If either of these parameters is null, the right thing happens
// anyway
throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
}
return reference;
}
/*
* All recent hotspots (as of 2009) *really* like to have the natural code
*
* if (guardExpression) { throw new BadException(messageExpression); }
*
* refactored so that messageExpression is moved to a separate String-returning method.
*
* if (guardExpression) { throw new BadException(badMsg(...)); }
*
* The alternative natural refactorings into void or Exception-returning methods are much slower. This is a big deal
* - we're talking factors of 2-8 in microbenchmarks, not just 10-20%. (This is a hotspot optimizer bug, which
* should be fixed, but that's a separate, big project).
*
* The coding pattern above is heavily used in java.util, e.g. in ArrayList. There is a RangeCheckMicroBenchmark in
* the JDK that was used to test this.
*
* But the methods in this class want to throw different exceptions, depending on the args, so it appears that this
* pattern is not directly applicable. But we can use the ridiculous, devious trick of throwing an exception in the
* middle of the construction of another exception. Hotspot is fine with that.
*/
/**
* Ensures that {@code index} specifies a valid <i>element</i> in an array, list or string of size {@code size}. An
* element index may range from zero, inclusive, to {@code size}, exclusive.
*
* @param index a user-supplied index identifying an element of an array, list or string
* @param size the size of that array, list or string
* @return the value of {@code index}
*/
public static int checkElementIndex(int index, int size) {
return checkElementIndex(index, size, "index");
}
/**
* Ensures that {@code index} specifies a valid <i>element</i> in an array, list or string of size {@code size}. An
* element index may range from zero, inclusive, to {@code size}, exclusive.
*
* @param index a user-supplied index identifying an element of an array, list or string
* @param size the size of that array, list or string
* @param desc the text to use to describe this index in an error message
* @return the value of {@code index}
*/
public static int checkElementIndex(int index, int size, @Nullable String desc) {
// Carefully optimized for execution by hotspot (explanatory comment
// above)
if (index < 0 || index >= size) {
throw new IndexOutOfBoundsException(buildBadElementIndexMessage(index, size, desc));
}
return index;
}
private static String buildBadElementIndexMessage(int index, int size, String desc) {
if (index < 0) {
return format("%s (%s) must not be negative", desc, index);
} else if (size < 0) {
throw new IllegalArgumentException("negative size: " + size);
} else { // index >= size
return format("%s (%s) must be less than size (%s)", desc, index, size);
}
}
/**
* Ensures that {@code index} specifies a valid <i>position</i> in an array, list or string of size {@code size}. A
* position index may range from zero to {@code size}, inclusive.
*
* @param index a user-supplied index identifying a position in an array, list or string
* @param size the size of that array, list or string
* @return the value of {@code index}
*/
public static int checkPositionIndex(int index, int size) {
return checkPositionIndex(index, size, "index");
}
/**
* Ensures that {@code index} specifies a valid <i>position</i> in an array, list or string of size {@code size}. A
* position index may range from zero to {@code size}, inclusive.
*
* @param index a user-supplied index identifying a position in an array, list or string
* @param size the size of that array, list or string
* @param desc the text to use to describe this index in an error message
* @return the value of {@code index}
*/
public static int checkPositionIndex(int index, int size, @Nullable String desc) {
// Carefully optimized for execution by hotspot (explanatory comment
// above)
if (index < 0 || index > size) {
throw new IndexOutOfBoundsException(buildBadPositionIndexMessage(index, size, desc));
}
return index;
}
private static String buildBadPositionIndexMessage(int index, int size, String desc) {
if (index < 0) {
return format("%s (%s) must not be negative", desc, index);
} else if (size < 0) {
throw new IllegalArgumentException("negative size: " + size);
} else { // index > size
return format("%s (%s) must not be greater than size (%s)", desc, index, size);
}
}
/**
* Ensures that {@code start} and {@code end} specify a valid <i>positions</i> in an array, list or string of size
* {@code size}, and are in order. A position index may range from zero to {@code size}, inclusive.
*
* @param start a user-supplied index identifying a starting position in an array, list or string
* @param end a user-supplied index identifying a ending position in an array, list or string
* @param size the size of that array, list or string
*/
public static void checkPositionIndexes(int start, int end, int size) {
// Carefully optimized for execution by hotspot (explanatory comment
// above)
if (start < 0 || end < start || end > size) {
throw new IndexOutOfBoundsException(buildBadPositionIndexesMessage(start, end, size));
}
}
private static String buildBadPositionIndexesMessage(int start, int end, int size) {
if (start < 0 || start > size) {
return buildBadPositionIndexMessage(start, size, "start index");
}
if (end < 0 || end > size) {
return buildBadPositionIndexMessage(end, size, "end index");
}
// end < start
return format("end index (%s) must not be less than start index (%s)", end, start);
}
/**
* Substitutes each {@code %s} in {@code template} with an argument. These are matched by position - the first
* {@code %s} gets {@code args[0]}, etc. If there are more arguments than placeholders, the unmatched arguments will
* be appended to the end of the formatted message in square braces.
*
* @param template a non-null string containing 0 or more {@code %s} placeholders.
* @param args the arguments to be substituted into the message template. Arguments are converted to strings using
* {@link String#valueOf(Object)}. Arguments can be null.
* @return formatted message
*/
static String format(String template, @Nullable Object... args) {
template = String.valueOf(template); // null -> "null"
// start substituting the arguments into the '%s' placeholders
StringBuilder builder = new StringBuilder(template.length() + DEFAULT_16 * args.length);
int templateStart = 0;
int i = 0;
while (i < args.length) {
int placeholderStart = template.indexOf("%s", templateStart);
if (placeholderStart == -1) {
break;
}
builder.append(template.substring(templateStart, placeholderStart));
builder.append(args[i++]);
templateStart = placeholderStart + 2;
}
builder.append(template.substring(templateStart));
// if we run out of placeholders, append the extra args in square braces
if (i < args.length) {
builder.append(" [");
builder.append(args[i++]);
while (i < args.length) {
builder.append(", ");
builder.append(args[i++]);
}
builder.append(']');
}
return builder.toString();
}
/**
* Ensures that given url is valid URL.
*
* @param url url String
* @return converted url
*/
public static URL checkValidURL(String url) {
try {
return new URL(url);
} catch (Exception e) {
throw new IllegalArgumentException("Url " + url + "should be valid", e);
}
}
}