Java tutorial
/* * Copyright 2019 ThoughtWorks, Inc. * * 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 com.thoughtworks.go.util; import org.apache.commons.lang3.StringUtils; // an object that represents a ruby like truthy public abstract class TriState { public static TriState UNSET = new TriState() { @Override public boolean isFalse() { return false; } @Override public boolean isTrue() { return false; } }; public static TriState TRUE = new TriState() { @Override public boolean isFalse() { return false; } @Override public boolean isTruthy() { return true; } }; public static TriState FALSE = new TriState() { }; private TriState() { } public boolean isTruthy() { return false; } public boolean isFalsy() { return !isTruthy(); } public boolean isFalse() { return true; } public boolean isTrue() { return !isFalse(); } public static TriState from(String booleanLike) { if (StringUtils.isBlank(booleanLike)) { return UNSET; } if (booleanLike.toLowerCase().equals("false")) { return FALSE; } if (booleanLike.toLowerCase().equals("true")) { return TRUE; } throw new IllegalArgumentException( String.format("The string '%s' does not look like a boolean.", booleanLike)); } public static TriState from(boolean booleanLike) { if (booleanLike) { return TRUE; } else { return FALSE; } } }