LogUtils.java

/*
 * Copyright (C) 2011 Google 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.android.utils;

import android.util.Log;

import java.util.IllegalFormatException;

/**
 * Handles logging formatted strings.
 */
public class LogUtils {
    private final static String TAG = "LogUtils";

    /**
     * The minimum log level that will be printed to the console. Set this to
     * {@link Log#ERROR} for release or {@link Log#VERBOSE} for debugging.
     */
    public static int LOG_LEVEL = Log.ERROR;

    /**
     * Logs a formatted string to the console using the source object's name as
     * the log tag. If the source object is null, the default tag (see
     * {@link LogUtils#TAG} is used.
     * <p>
     * Example usage: <br>
     * <code>
     * LogUtils.log(this, Log.ERROR, "Invalid value: %d", value);
     * </code>
     *
     * @param source The object that generated the log event.
     * @param priority The log entry priority, see
     *            {@link Log#println(int, String, String)}.
     * @param format A format string, see
     *            {@link String#format(String, Object...)}.
     * @param args String formatter arguments.
     */
    public static void log(Object source, int priority, String format, Object... args) {
        if (priority < LOG_LEVEL) {
            return;
        }

        final String sourceClass;

        if (source == null) {
            sourceClass = TAG;
        } else if (source instanceof Class<?>) {
            sourceClass = ((Class<?>) source).getSimpleName();
        } else {
            sourceClass = source.getClass().getSimpleName();
        }

        try {
            Log.println(priority, sourceClass, String.format(format, args));
        } catch (IllegalFormatException e) {
            Log.e(TAG, "Bad formatting string: \"" + format + "\"", e);
        }
    }

    /**
     * Logs a formatted string to the console using the default tag (see
     * {@link LogUtils#TAG}.
     *
     * @param priority The log entry priority, see
     *            {@link Log#println(int, String, String)}.
     * @param format A format string, see
     *            {@link String#format(String, Object...)}.
     * @param args String formatter arguments.
     */
    public static void log(int priority, String format, Object... args) {
        log(null, priority, format, args);
    }

    /**
     * Logs a formatted string to the console using the default tag (see
     * {@link LogUtils#TAG}. If the index is greater than the limit, then the log entry is skipped.
     *
     * @param index The index of the log entry in the current log sequence.
     * @param limit The maximum number of log entries allowed in the current sequence.
     * @param priority The log entry priority, see
     *            {@link Log#println(int, String, String)}.
     * @param format A format string, see
     *            {@link String#format(String, Object...)}.
     * @param args String formatter arguments.
     */
    public static void logWithLimit(Object source, int priority, int index, int limit,
            String format, Object... args) {
        String formatWithIndex;
        if (index > limit) {
            return;
        } else if (index == limit) {
            formatWithIndex = String.format("%s (%d); further messages suppressed", format, index);
        } else {
            formatWithIndex = String.format("%s (%d)", format, index);
        }

        log(source, priority, formatWithIndex, args);
    }

    /**
     * Sets the log display level.
     *
     * @param logLevel The minimum log level that will be printed to the
     *            console.
     */
    public static void setLogLevel(int logLevel) {
        LOG_LEVEL = logLevel;
    }
}