Java tutorial
//package com.java2s; /* * 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. */ public class Main { /** * <p>Converts a Boolean to a boolean handling {@code null} * by returning {@code false}.</p> * * <pre> * BooleanUtils.toBoolean(Boolean.TRUE) = true * BooleanUtils.toBoolean(Boolean.FALSE) = false * BooleanUtils.toBoolean(null) = false * </pre> * * @param bool the boolean to convert * @return {@code true} or {@code false}, {@code null} returns {@code false} */ public static boolean toBoolean(final Boolean bool) { return bool != null && bool.booleanValue(); } /** * <p>Converts an int to a boolean using the convention that {@code zero} * is {@code false}.</p> * * <pre> * BooleanUtils.toBoolean(0) = false * BooleanUtils.toBoolean(1) = true * BooleanUtils.toBoolean(2) = true * </pre> * * @param value the int to convert * @return {@code true} if non-zero, {@code false} * if zero */ public static boolean toBoolean(final int value) { return value != 0; } /** * <p>Converts an int to a boolean specifying the conversion values.</p> * * <pre> * BooleanUtils.toBoolean(0, 1, 0) = false * BooleanUtils.toBoolean(1, 1, 0) = true * BooleanUtils.toBoolean(2, 1, 2) = false * BooleanUtils.toBoolean(2, 2, 0) = true * </pre> * * @param value the Integer to convert * @param trueValue the value to match for {@code true} * @param falseValue the value to match for {@code false} * @return {@code true} or {@code false} * @throws IllegalArgumentException if no match */ public static boolean toBoolean(final int value, final int trueValue, final int falseValue) { if (value == trueValue) { return true; } if (value == falseValue) { return false; } // no match throw new IllegalArgumentException("The Integer did not match either specified value"); } /** * <p>Converts an Integer to a boolean specifying the conversion values.</p> * * <pre> * BooleanUtils.toBoolean(Integer.valueOf(0), Integer.valueOf(1), Integer.valueOf(0)) = false * BooleanUtils.toBoolean(Integer.valueOf(1), Integer.valueOf(1), Integer.valueOf(0)) = true * BooleanUtils.toBoolean(Integer.valueOf(2), Integer.valueOf(1), Integer.valueOf(2)) = false * BooleanUtils.toBoolean(Integer.valueOf(2), Integer.valueOf(2), Integer.valueOf(0)) = true * BooleanUtils.toBoolean(null, null, Integer.valueOf(0)) = true * </pre> * * @param value the Integer to convert * @param trueValue the value to match for {@code true}, may be {@code null} * @param falseValue the value to match for {@code false}, may be {@code null} * @return {@code true} or {@code false} * @throws IllegalArgumentException if no match */ public static boolean toBoolean(final Integer value, final Integer trueValue, final Integer falseValue) { if (value == null) { if (trueValue == null) { return true; } if (falseValue == null) { return false; } } else if (value.equals(trueValue)) { return true; } else if (value.equals(falseValue)) { return false; } // no match throw new IllegalArgumentException("The Integer did not match either specified value"); } /** * <p>Converts a String to a boolean (optimised for performance).</p> * * <p>{@code 'true'}, {@code 'on'}, {@code 'y'}, {@code 't'} or {@code 'yes'} * (case insensitive) will return {@code true}. Otherwise, * {@code false} is returned.</p> * * <p>This method performs 4 times faster (JDK1.4) than * {@code Boolean.valueOf(String)}. However, this method accepts * 'on' and 'yes', 't', 'y' as true values. * * <pre> * BooleanUtils.toBoolean(null) = false * BooleanUtils.toBoolean("true") = true * BooleanUtils.toBoolean("TRUE") = true * BooleanUtils.toBoolean("tRUe") = true * BooleanUtils.toBoolean("on") = true * BooleanUtils.toBoolean("yes") = true * BooleanUtils.toBoolean("false") = false * BooleanUtils.toBoolean("x gti") = false * BooleanUtils.toBooleanObject("y") = true * BooleanUtils.toBooleanObject("n") = false * BooleanUtils.toBooleanObject("t") = true * BooleanUtils.toBooleanObject("f") = false * </pre> * * @param str the String to check * @return the boolean value of the string, {@code false} if no match or the String is null */ public static boolean toBoolean(final String str) { return toBooleanObject(str) == Boolean.TRUE; } /** * <p>Converts a String to a Boolean throwing an exception if no match found.</p> * * <pre> * BooleanUtils.toBoolean("true", "true", "false") = true * BooleanUtils.toBoolean("false", "true", "false") = false * </pre> * * @param str the String to check * @param trueString the String to match for {@code true} (case sensitive), may be {@code null} * @param falseString the String to match for {@code false} (case sensitive), may be {@code null} * @return the boolean value of the string * @throws IllegalArgumentException if the String doesn't match */ public static boolean toBoolean(final String str, final String trueString, final String falseString) { if (str == trueString) { return true; } else if (str == falseString) { return false; } else if (str != null) { if (str.equals(trueString)) { return true; } else if (str.equals(falseString)) { return false; } } // no match throw new IllegalArgumentException("The String did not match either specified value"); } /** * <p>Converts an int to a Boolean using the convention that {@code zero} * is {@code false}.</p> * * <pre> * BooleanUtils.toBoolean(0) = Boolean.FALSE * BooleanUtils.toBoolean(1) = Boolean.TRUE * BooleanUtils.toBoolean(2) = Boolean.TRUE * </pre> * * @param value the int to convert * @return Boolean.TRUE if non-zero, Boolean.FALSE if zero, * {@code null} if {@code null} */ public static Boolean toBooleanObject(final int value) { return value == 0 ? Boolean.FALSE : Boolean.TRUE; } /** * <p>Converts an Integer to a Boolean using the convention that {@code zero} * is {@code false}.</p> * * <p>{@code null} will be converted to {@code null}.</p> * * <p>NOTE: This returns null and will throw a NullPointerException if autoboxed to a boolean. </p> * * <pre> * BooleanUtils.toBoolean(Integer.valueOf(0)) = Boolean.FALSE * BooleanUtils.toBoolean(Integer.valueOf(1)) = Boolean.TRUE * BooleanUtils.toBoolean(Integer.valueOf(null)) = null * </pre> * * @param value the Integer to convert * @return Boolean.TRUE if non-zero, Boolean.FALSE if zero, * {@code null} if {@code null} input */ public static Boolean toBooleanObject(final Integer value) { if (value == null) { return null; } return value.intValue() == 0 ? Boolean.FALSE : Boolean.TRUE; } /** * <p>Converts an int to a Boolean specifying the conversion values.</p> * * <p>NOTE: This returns null and will throw a NullPointerException if autoboxed to a boolean. </p> * * <pre> * BooleanUtils.toBooleanObject(0, 0, 2, 3) = Boolean.TRUE * BooleanUtils.toBooleanObject(2, 1, 2, 3) = Boolean.FALSE * BooleanUtils.toBooleanObject(3, 1, 2, 3) = null * </pre> * * @param value the Integer to convert * @param trueValue the value to match for {@code true} * @param falseValue the value to match for {@code false} * @param nullValue the value to to match for {@code null} * @return Boolean.TRUE, Boolean.FALSE, or {@code null} * @throws IllegalArgumentException if no match */ public static Boolean toBooleanObject(final int value, final int trueValue, final int falseValue, final int nullValue) { if (value == trueValue) { return Boolean.TRUE; } if (value == falseValue) { return Boolean.FALSE; } if (value == nullValue) { return null; } // no match throw new IllegalArgumentException("The Integer did not match any specified value"); } /** * <p>Converts an Integer to a Boolean specifying the conversion values.</p> * * <p>NOTE: This returns null and will throw a NullPointerException if autoboxed to a boolean. </p> * * <pre> * BooleanUtils.toBooleanObject(Integer.valueOf(0), Integer.valueOf(0), Integer.valueOf(2), Integer.valueOf(3)) = Boolean.TRUE * BooleanUtils.toBooleanObject(Integer.valueOf(2), Integer.valueOf(1), Integer.valueOf(2), Integer.valueOf(3)) = Boolean.FALSE * BooleanUtils.toBooleanObject(Integer.valueOf(3), Integer.valueOf(1), Integer.valueOf(2), Integer.valueOf(3)) = null * </pre> * * @param value the Integer to convert * @param trueValue the value to match for {@code true}, may be {@code null} * @param falseValue the value to match for {@code false}, may be {@code null} * @param nullValue the value to to match for {@code null}, may be {@code null} * @return Boolean.TRUE, Boolean.FALSE, or {@code null} * @throws IllegalArgumentException if no match */ public static Boolean toBooleanObject(final Integer value, final Integer trueValue, final Integer falseValue, final Integer nullValue) { if (value == null) { if (trueValue == null) { return Boolean.TRUE; } if (falseValue == null) { return Boolean.FALSE; } if (nullValue == null) { return null; } } else if (value.equals(trueValue)) { return Boolean.TRUE; } else if (value.equals(falseValue)) { return Boolean.FALSE; } else if (value.equals(nullValue)) { return null; } // no match throw new IllegalArgumentException("The Integer did not match any specified value"); } /** * <p>Converts a String to a Boolean.</p> * * <p>{@code 'true'}, {@code 'on'}, {@code 'y'}, {@code 't'} or {@code 'yes'} * (case insensitive) will return {@code true}. * {@code 'false'}, {@code 'off'}, {@code 'n'}, {@code 'f'} or {@code 'no'} * (case insensitive) will return {@code false}. * Otherwise, {@code null} is returned.</p> * * <p>NOTE: This returns null and will throw a NullPointerException if autoboxed to a boolean. </p> * * <pre> * // N.B. case is not significant * BooleanUtils.toBooleanObject(null) = null * BooleanUtils.toBooleanObject("true") = Boolean.TRUE * BooleanUtils.toBooleanObject("T") = Boolean.TRUE // i.e. T[RUE] * BooleanUtils.toBooleanObject("false") = Boolean.FALSE * BooleanUtils.toBooleanObject("f") = Boolean.FALSE // i.e. f[alse] * BooleanUtils.toBooleanObject("No") = Boolean.FALSE * BooleanUtils.toBooleanObject("n") = Boolean.FALSE // i.e. n[o] * BooleanUtils.toBooleanObject("on") = Boolean.TRUE * BooleanUtils.toBooleanObject("ON") = Boolean.TRUE * BooleanUtils.toBooleanObject("off") = Boolean.FALSE * BooleanUtils.toBooleanObject("oFf") = Boolean.FALSE * BooleanUtils.toBooleanObject("yes") = Boolean.TRUE * BooleanUtils.toBooleanObject("Y") = Boolean.TRUE // i.e. Y[ES] * BooleanUtils.toBooleanObject("blue") = null * </pre> * * @param str the String to check; upper and lower case are treated as the same * @return the Boolean value of the string, {@code null} if no match or {@code null} input */ public static Boolean toBooleanObject(final String str) { // Previously used equalsIgnoreCase, which was fast for interned 'true'. // Non interned 'true' matched 15 times slower. // // Optimisation provides same performance as before for interned 'true'. // Similar performance for null, 'false', and other strings not length 2/3/4. // 'true'/'TRUE' match 4 times slower, 'tRUE'/'True' 7 times slower. if (str == "true") { return Boolean.TRUE; } if (str == null) { return null; } switch (str.length()) { case 1: { final char ch0 = str.charAt(0); if (ch0 == 'y' || ch0 == 'Y' || ch0 == 't' || ch0 == 'T') { return Boolean.TRUE; } if (ch0 == 'n' || ch0 == 'N' || ch0 == 'f' || ch0 == 'F') { return Boolean.FALSE; } break; } case 2: { final char ch0 = str.charAt(0); final char ch1 = str.charAt(1); if ((ch0 == 'o' || ch0 == 'O') && (ch1 == 'n' || ch1 == 'N')) { return Boolean.TRUE; } if ((ch0 == 'n' || ch0 == 'N') && (ch1 == 'o' || ch1 == 'O')) { return Boolean.FALSE; } break; } case 3: { final char ch0 = str.charAt(0); final char ch1 = str.charAt(1); final char ch2 = str.charAt(2); if ((ch0 == 'y' || ch0 == 'Y') && (ch1 == 'e' || ch1 == 'E') && (ch2 == 's' || ch2 == 'S')) { return Boolean.TRUE; } if ((ch0 == 'o' || ch0 == 'O') && (ch1 == 'f' || ch1 == 'F') && (ch2 == 'f' || ch2 == 'F')) { return Boolean.FALSE; } break; } case 4: { final char ch0 = str.charAt(0); final char ch1 = str.charAt(1); final char ch2 = str.charAt(2); final char ch3 = str.charAt(3); if ((ch0 == 't' || ch0 == 'T') && (ch1 == 'r' || ch1 == 'R') && (ch2 == 'u' || ch2 == 'U') && (ch3 == 'e' || ch3 == 'E')) { return Boolean.TRUE; } break; } case 5: { final char ch0 = str.charAt(0); final char ch1 = str.charAt(1); final char ch2 = str.charAt(2); final char ch3 = str.charAt(3); final char ch4 = str.charAt(4); if ((ch0 == 'f' || ch0 == 'F') && (ch1 == 'a' || ch1 == 'A') && (ch2 == 'l' || ch2 == 'L') && (ch3 == 's' || ch3 == 'S') && (ch4 == 'e' || ch4 == 'E')) { return Boolean.FALSE; } break; } } return null; } /** * <p>Converts a String to a Boolean throwing an exception if no match.</p> * * <p>NOTE: This returns null and will throw a NullPointerException if autoboxed to a boolean. </p> * * <pre> * BooleanUtils.toBooleanObject("true", "true", "false", "null") = Boolean.TRUE * BooleanUtils.toBooleanObject("false", "true", "false", "null") = Boolean.FALSE * BooleanUtils.toBooleanObject("null", "true", "false", "null") = null * </pre> * * @param str the String to check * @param trueString the String to match for {@code true} (case sensitive), may be {@code null} * @param falseString the String to match for {@code false} (case sensitive), may be {@code null} * @param nullString the String to match for {@code null} (case sensitive), may be {@code null} * @return the Boolean value of the string, {@code null} if either the String matches {@code nullString} * or if {@code null} input and {@code nullString} is {@code null} * @throws IllegalArgumentException if the String doesn't match */ public static Boolean toBooleanObject(final String str, final String trueString, final String falseString, final String nullString) { if (str == null) { if (trueString == null) { return Boolean.TRUE; } if (falseString == null) { return Boolean.FALSE; } if (nullString == null) { return null; } } else if (str.equals(trueString)) { return Boolean.TRUE; } else if (str.equals(falseString)) { return Boolean.FALSE; } else if (str.equals(nullString)) { return null; } // no match throw new IllegalArgumentException("The String did not match any specified value"); } }