/*
* Copyright (C) 2006 The Android Open Source Project
*
* 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 android.util;
import com.android.internal.os.RuntimeInit;
import java.io.PrintWriter;
import java.io.StringWriter;
/**
* API for sending log output.
*
* <p>Generally, use the Log.v() Log.d() Log.i() Log.w() and Log.e()
* methods.
*
* <p>The order in terms of verbosity, from least to most is
* ERROR, WARN, INFO, DEBUG, VERBOSE. Verbose should never be compiled
* into an application except during development. Debug logs are compiled
* in but stripped at runtime. Error, warning and info logs are always kept.
*
* <p><b>Tip:</b> A good convention is to declare a <code>TAG</code> constant
* in your class:
*
* <pre>private static final String TAG = "MyActivity";</pre>
*
* and use that in subsequent calls to the log methods.
* </p>
*
* <p><b>Tip:</b> Don't forget that when you make a call like
* <pre>Log.v(TAG, "index=" + i);</pre>
* that when you're building the string to pass into Log.d, the compiler uses a
* StringBuilder and at least three allocations occur: the StringBuilder
* itself, the buffer, and the String object. Realistically, there is also
* another buffer allocation and copy, and even more pressure on the gc.
* That means that if your log message is filtered out, you might be doing
* significant work and incurring significant overhead.
*/
public final class Log {
/**
* Priority constant for the println method; use Log.v.
*/
public static final int VERBOSE = 2;
/**
* Priority constant for the println method; use Log.d.
*/
public static final int DEBUG = 3;
/**
* Priority constant for the println method; use Log.i.
*/
public static final int INFO = 4;
/**
* Priority constant for the println method; use Log.w.
*/
public static final int WARN = 5;
/**
* Priority constant for the println method; use Log.e.
*/
public static final int ERROR = 6;
/**
* Priority constant for the println method.
*/
public static final int ASSERT = 7;
private Log() {
}
/**
* Send a {@link #VERBOSE} log message.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
*/
public static int v(String tag, String msg) {
return println(VERBOSE, tag, msg);
}
/**
* Send a {@link #VERBOSE} log message and log the exception.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
* @param tr An exception to log
*/
public static int v(String tag, String msg, Throwable tr) {
return println(VERBOSE, tag, msg + '\n' + getStackTraceString(tr));
}
/**
* Send a {@link #DEBUG} log message.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
*/
public static int d(String tag, String msg) {
return println(DEBUG, tag, msg);
}
/**
* Send a {@link #DEBUG} log message and log the exception.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
* @param tr An exception to log
*/
public static int d(String tag, String msg, Throwable tr) {
return println(DEBUG, tag, msg + '\n' + getStackTraceString(tr));
}
/**
* Send an {@link #INFO} log message.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
*/
public static int i(String tag, String msg) {
return println(INFO, tag, msg);
}
/**
* Send a {@link #INFO} log message and log the exception.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
* @param tr An exception to log
*/
public static int i(String tag, String msg, Throwable tr) {
return println(INFO, tag, msg + '\n' + getStackTraceString(tr));
}
/**
* Send a {@link #WARN} log message.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
*/
public static int w(String tag, String msg) {
return println(WARN, tag, msg);
}
/**
* Send a {@link #WARN} log message and log the exception.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
* @param tr An exception to log
*/
public static int w(String tag, String msg, Throwable tr) {
return println(WARN, tag, msg + '\n' + getStackTraceString(tr));
}
/**
* Checks to see whether or not a log for the specified tag is loggable at the specified level.
*
* The default level of any tag is set to INFO. This means that any level above and including
* INFO will be logged. Before you make any calls to a logging method you should check to see
* if your tag should be logged. You can change the default level by setting a system property:
* 'setprop log.tag.<YOUR_LOG_TAG> <LEVEL>'
* Where level is either VERBOSE, DEBUG, INFO, WARN, ERROR, ASSERT, or SUPPRESS. SUPRESS will
* turn off all logging for your tag. You can also create a local.prop file that with the
* following in it:
* 'log.tag.<YOUR_LOG_TAG>=<LEVEL>'
* and place that in /data/local.prop.
*
* @param tag The tag to check.
* @param level The level to check.
* @return Whether or not that this is allowed to be logged.
* @throws IllegalArgumentException is thrown if the tag.length() > 23.
*/
public static native boolean isLoggable(String tag, int level);
/*
* Send a {@link #WARN} log message and log the exception.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param tr An exception to log
*/
public static int w(String tag, Throwable tr) {
return println(WARN, tag, getStackTraceString(tr));
}
/**
* Send an {@link #ERROR} log message.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
*/
public static int e(String tag, String msg) {
return println(ERROR, tag, msg);
}
/**
* Send a {@link #ERROR} log message and log the exception.
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
* @param tr An exception to log
*/
public static int e(String tag, String msg, Throwable tr) {
int r = println(ERROR, tag, msg + '\n' + getStackTraceString(tr));
RuntimeInit.reportException(tag, tr, false); // asynchronous
return r;
}
/**
* Handy function to get a loggable stack trace from a Throwable
* @param tr An exception to log
*/
public static String getStackTraceString(Throwable tr) {
if (tr == null) {
return "";
}
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
tr.printStackTrace(pw);
return sw.toString();
}
/**
* Low-level logging call.
* @param priority The priority/type of this log message
* @param tag Used to identify the source of a log message. It usually identifies
* the class or activity where the log call occurs.
* @param msg The message you would like logged.
* @return The number of bytes written.
*/
public static native int println(int priority, String tag, String msg);
}
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