Java tutorial
/* * 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. */ package com.framework.utils.error; import org.apache.commons.lang3.StringUtils; /** * Static convenience methods that help a method or constructor check whether it was invoked * correctly (whether its <i>preconditions</i> have been met). These methods generally accept a * {@code boolean} expression which is expected to be {@code true} (or in the case of {@code * checkNotNull}, an object reference which is expected to be non-null). When {@code false} (or * {@code null}) is passed instead, the {@code Preconditions} method throws an unchecked exception, * which helps the calling method communicate to <i>its</i> caller that <i>that</i> caller has made a mistake. * Verifies correct argument values and state. Borrowed from Guava. */ public final class PreConditions { //region PreConditions - Constructor Methods Section private PreConditions() { // util } //endregion //region PreConditions - Check Argument Methods Section /** * 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)} * * @throws IllegalArgumentException if {@code expression} is false * * @see com.google.common.base.Preconditions#checkArgument(boolean, Object) */ public static void checkArgument(boolean expression, 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)}. * * @throws IllegalArgumentException if {@code expression} is false * @throws NullPointerException if the check fails and either {@code errorMessageTemplate} or * {@code errorMessageArgs} is null (don't let this happen) * * @see com.google.common.base.Preconditions#checkArgument(boolean, String, Object...) */ public static void checkArgument(boolean expression, String errorMessageTemplate, Object... errorMessageArgs) { if (!expression) { throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs)); } } //endregion //region PreConditions - Check State Methods Section /** * 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)} * * @throws IllegalStateException if {@code expression} is false * * @see com.google.common.base.Preconditions#checkState(boolean, Object) */ public static void checkState(boolean expression, 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)}. * * @throws IllegalStateException if {@code expression} is false * @throws NullPointerException if the check fails and either {@code errorMessageTemplate} or * {@code errorMessageArgs} is null (don't let this happen) * * @see com.google.common.base.Preconditions#checkState(boolean, String, Object...) */ public static void checkState(boolean expression, String errorMessageTemplate, Object... errorMessageArgs) { if (!expression) { throw new IllegalStateException(format(errorMessageTemplate, errorMessageArgs)); } } //todo: documentation public static void checkInstanceOf(final Class<?> type, final Object obj, String errorMessageTemplate, Object... errorMessageArgs) { if (!type.isInstance(obj)) { throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs)); } } //endregion //region PreConditions - Check Not Null Methods Section /** * Ensures that an object reference passed as a parameter to the calling method is not null. * * @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 * * @throws NullPointerException if {@code reference} is null */ public static <T> T checkNotNull(T reference, Object errorMessage) { if (reference == null) { throw new PreConditionException(new NullPointerException(String.valueOf(errorMessage))); } return reference; } /** * Ensures that an object reference passed as a parameter to the calling method is not null. * * @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 * * @throws NullPointerException if {@code reference} is null */ public static <T> T checkNotNull(T reference, String errorMessageTemplate, Object... errorMessageArgs) { if (reference == null) { // If either of these parameters is null, the right thing happens anyway throw new PreConditionException( new NullPointerException(format(errorMessageTemplate, errorMessageArgs))); } return reference; } //endregion //region PreConditions - Check Element Index Methods Section /** * 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} * * @throws IndexOutOfBoundsException if {@code index} is negative or is not less than {@code size} * @throws IllegalArgumentException if {@code size} is negative */ public static int checkElementIndex(int index, int size, String desc) { // Carefully optimized for execution by hotspot (explanatory comment above) if (index < 0 || index >= size) { throw new PreConditionException(new IndexOutOfBoundsException(badElementIndex(index, size, desc))); } return 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} * * @throws IndexOutOfBoundsException if {@code index} is negative or is greater than {@code size} * @throws IllegalArgumentException if {@code size} is negative */ public static int checkPositionIndex(int index, int size, String desc) { // Carefully optimized for execution by hotspot (explanatory comment above) if (index < 0 || index > size) { throw new PreConditionException(new IndexOutOfBoundsException(badPositionIndex(index, size, desc))); } return index; } /** * Ensures that {@code startTest} and {@code endTest} 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 * * @throws IndexOutOfBoundsException if either index is negative or is greater than {@code size}, * or if {@code endTest} is less than {@code startTest} * @throws IllegalArgumentException if {@code size} is negative */ 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 PreConditionException(new IndexOutOfBoundsException(badPositionIndexes(start, end, size))); } } private static String badElementIndex(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 PreConditionException(new IllegalArgumentException("negative size: " + size)); } else { // index >= size return format("%s (%s) must be less than size (%s)", desc, index, size); } } private static String badPositionIndex(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 PreConditionException(new IllegalArgumentException("negative size: " + size)); } else { // index > size return format("%s (%s) must not be greater than size (%s)", desc, index, size); } } private static String badPositionIndexes(int start, int end, int size) { if (start < 0 || start > size) { return badPositionIndex(start, size, "startTest index"); } if (end < 0 || end > size) { return badPositionIndex(end, size, "endTest index"); } // endTest < startTest return format("endTest index (%s) must not be less than startTest index (%s)", end, start); } //endregion //region PreConditions - Check Null, Empty or Blank Methods Section /** * Verifies that the given {@code String} is not {@code null} or empty. * * @param s the given {@code String}. * @param message error message in case of empty {@code String}. * * @return the validated {@code String}. * * @throws NullPointerException if the given {@code String} is {@code null}. * @throws IllegalArgumentException if the given {@code String} is empty. */ public static String checkNotNullOrEmpty(String s, String message) { checkNotNull(s, message); if (s.isEmpty()) { throw new PreConditionException(new IllegalArgumentException(message)); } return s; } /** * Verifies that the given {@code String} is not {@code null} or empty. * * @param s a String 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 validated {@code String}. * * @throws NullPointerException if the given {@code String} is {@code null}. * @throws IllegalArgumentException if the given {@code String} is empty. */ public static String checkNotNullOrEmpty(String s, String errorMessageTemplate, Object... errorMessageArgs) { checkNotNull(s, format(errorMessageTemplate, errorMessageArgs)); if (s.isEmpty()) { throw new PreConditionException( new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs))); } return s; } /** * Verifies that the given {@code String} is not {@code null}, blank or empty. * * @param s the given {@code String}. * @param message error message in case of empty {@code String}. * * @return the validated {@code String}. * * @throws NullPointerException if the given {@code String} is {@code null}. * @throws IllegalArgumentException if the given {@code String} is empty. */ public static String checkNotNullNotBlankOrEmpty(String s, String message) { checkNotNull(s, message); if (s.isEmpty()) { throw new PreConditionException(new IllegalArgumentException(message)); } if (StringUtils.isBlank(s)) { throw new PreConditionException(new IllegalArgumentException(message)); } return s; } /** * Verifies that the given {@code String} is not {@code null}, blank or empty. * * @param s a String 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 validated {@code String}. * * @throws NullPointerException if the given {@code String} is {@code null}. * @throws IllegalArgumentException if the given {@code String} is empty or blank. */ public static String checkNotNullNotBlankOrEmpty(String s, String errorMessageTemplate, Object... errorMessageArgs) { checkNotNull(s, format(errorMessageTemplate, errorMessageArgs)); if (s.isEmpty()) { throw new PreConditionException( new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs))); } if (StringUtils.isBlank(s)) { throw new PreConditionException( new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs))); } return s; } //endregion //region PreConditions - Check WebElement Methods Section // public static WebElement checkElementTagName( final WebElement element, final String tagName ) // { // String actual = element.getTagName(); // if ( null == actual || ! tagName.equals( actual.toLowerCase() ) ) // { // throw new UnexpectedTagNameException( tagName, actual ); // } // // return element; // } // public static WebElement checkElementAttribute( final WebElement element, final String attributeName, final String attributeValue ) // { // String actual = element.getAttribute( attributeName ); // if ( null == actual || ! actual.equals( attributeValue.toLowerCase() ) ) // { // throw new UnexpectedAttributeValueException( attributeName, attributeValue, actual ); // } // // return element; // } //endregion //region PreConditions - Private Function Section /** * 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 endTest 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. */ // Note that this is somewhat-improperly used from Verify.java as well. static String format(String template, Object... args) { template = String.valueOf(template); // null -> "null" // startTest substituting the arguments into the '%s' placeholders StringBuilder builder = new StringBuilder(template.length() + 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(); } //endregion }