    001    /*
    002     * Copyright (C) 2010 The Guava Authors
    003     *
    004     * Licensed under the Apache License, Version 2.0 (the "License");
    005     * you may not use this file except in compliance with the License.
    006     * You may obtain a copy of the License at
    007     *
    008     * http://www.apache.org/licenses/LICENSE-2.0
    009     *
    010     * Unless required by applicable law or agreed to in writing, software
    011     * distributed under the License is distributed on an "AS IS" BASIS,
    012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    013     * See the License for the specific language governing permissions and
    014     * limitations under the License.
    015     */
    016
    017    package com.google.common.util.concurrent;
    018
    019    import static java.util.logging.Level.SEVERE;
    020
    021    import com.google.common.annotations.VisibleForTesting;
    022
    023    import java.lang.Thread.UncaughtExceptionHandler;
    024    import java.util.logging.Logger;
    025
    026    /**
    027     * Factories for {@link UncaughtExceptionHandler} instances.
    028     *
    029     * @author Gregory Kick
    030     * @since 8.0
    031     */
    032    public final class UncaughtExceptionHandlers {
    033      private UncaughtExceptionHandlers() {}
    034
    035      /**
    036       * Returns an exception handler that exits the system. This is particularly useful for the main
    037       * thread, which may start up other, non-daemon threads, but fail to fully initialize the
    038       * application successfully.
    039       *
    040       * <p>Example usage:
    041       * <pre>public static void main(String[] args) {
    042       *   Thread.currentThread().setUncaughtExceptionHandler(UncaughtExceptionHandlers.systemExit());
    043       *   ...
    044       * </pre>
    045       */
    046      public static UncaughtExceptionHandler systemExit() {
    047        return new Exiter(Runtime.getRuntime());
    048      }
    049
    050      @VisibleForTesting static final class Exiter implements UncaughtExceptionHandler {
    051        private static final Logger logger = Logger.getLogger(Exiter.class.getName());
    052
    053        private final Runtime runtime;
    054
    055        Exiter(Runtime runtime) {
    056          this.runtime = runtime;
    057        }
    058
    059        @Override public void uncaughtException(Thread t, Throwable e) {
    060          // cannot use FormattingLogger due to a dependency loop
    061          logger.log(SEVERE, String.format("Caught an exception in %s.  Shutting down.", t), e);
    062          runtime.exit(1);
    063        }
    064      }
    065    }