| java.lang.Object | |
| ↳ | android.util.Log |
Class Overview
API for sending log output.
Generally, use the Log.v() Log.d() Log.i() Log.w() and Log.e()
methods.
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.
Tip: A good convention is to declare a
TAG constant
in your class:
private static final String TAG = "MyActivity";and use that in subsequent calls to the log methods. Tip: Don't forget that when you make a call like
Log.v(TAG, "index=" + i);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.
Summary
| Constants | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| int | ASSERT | Priority constant for the println method. | |||||||||
| int | DEBUG | Priority constant for the println method; use Log.d. | |||||||||
| int | ERROR | Priority constant for the println method; use Log.e. | |||||||||
| int | INFO | Priority constant for the println method; use Log.i. | |||||||||
| int | VERBOSE | Priority constant for the println method; use Log.v. | |||||||||
| int | WARN | Priority constant for the println method; use Log.w. | |||||||||
| Public Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Send a
DEBUG log message. | |||||||||||
Send a
DEBUG log message and log the exception. | |||||||||||
Send an
ERROR log message. | |||||||||||
Send a
ERROR log message and log the exception. | |||||||||||
Handy function to get a loggable stack trace from a Throwable
| |||||||||||
Send an
INFO log message. | |||||||||||
Send a
INFO log message and log the exception. | |||||||||||
Checks to see whether or not a log for the specified tag is loggable at the specified level.
| |||||||||||
Low-level logging call.
| |||||||||||
Send a
VERBOSE log message. | |||||||||||
Send a
VERBOSE log message and log the exception. | |||||||||||
Send a
WARN log message and log the exception. | |||||||||||
Send a
WARN log message. | |||||||||||
What a Terrible Failure: Report an exception that should never happen.
| |||||||||||
What a Terrible Failure: Report a condition that should never happen.
| |||||||||||
What a Terrible Failure: Report an exception that should never happen.
| |||||||||||
| [Expand]
Inherited Methods
| |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.lang.Object
| |||||||||||
Constants
public static final int ASSERT
Added in API level 1
Priority constant for the println method.
Constant Value:
7
(0x00000007)
public static final int DEBUG
Added in API level 1
Priority constant for the println method; use Log.d.
Constant Value:
3
(0x00000003)
public static final int ERROR
Added in API level 1
Priority constant for the println method; use Log.e.
Constant Value:
6
(0x00000006)
public static final int INFO
Added in API level 1
Priority constant for the println method; use Log.i.
Constant Value:
4
(0x00000004)
public static final int VERBOSE
Added in API level 1
Priority constant for the println method; use Log.v.
Constant Value:
2
(0x00000002)
public static final int WARN
Added in API level 1
Priority constant for the println method; use Log.w.
Constant Value:
5
(0x00000005)
Public Methods
public static int d (String tag, String msg)
Added in API level 1
Send a
DEBUG log message.Parameters
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
|---|---|
| msg | The message you would like logged. |
public static int d (String tag, String msg, Throwable tr)
Added in API level 1
Send a
DEBUG log message and log the exception.Parameters
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
|---|---|
| msg | The message you would like logged. |
| tr | An exception to log |
public static int e (String tag, String msg)
Added in API level 1
Send an
ERROR log message.Parameters
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
|---|---|
| msg | The message you would like logged. |
public static int e (String tag, String msg, Throwable tr)
Added in API level 1
Send a
ERROR log message and log the exception.Parameters
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
|---|---|
| msg | The message you would like logged. |
| tr | An exception to log |
public static String getStackTraceString (Throwable tr)
Added in API level 1
Handy function to get a loggable stack trace from a Throwable
Parameters
| tr | An exception to log |
|---|
public static int i (String tag, String msg)
Added in API level 1
Send an
INFO log message.Parameters
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
|---|---|
| msg | The message you would like logged. |
public static int i (String tag, String msg, Throwable tr)
Added in API level 1
Send a
INFO log message and log the exception.Parameters
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
|---|---|
| msg | The message you would like logged. |
| tr | An exception to log |
public static boolean isLoggable (String tag, int level)
Added in API level 1
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. SUPPRESS 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.
Parameters
| tag | The tag to check. |
|---|---|
| level | The level to check. |
Returns
- Whether or not that this is allowed to be logged.
Throws
| IllegalArgumentException | is thrown if the tag.length() > 23. |
|---|
public static int println (int priority, String tag, String msg)
Added in API level 1
Low-level logging call.
Parameters
| priority | The priority/type of this log message |
|---|---|
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
| msg | The message you would like logged. |
Returns
- The number of bytes written.
public static int v (String tag, String msg)
Added in API level 1
Send a
VERBOSE log message.Parameters
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
|---|---|
| msg | The message you would like logged. |
public static int v (String tag, String msg, Throwable tr)
Added in API level 1
Send a
VERBOSE log message and log the exception.Parameters
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
|---|---|
| msg | The message you would like logged. |
| tr | An exception to log |
public static int w (String tag, String msg, Throwable tr)
Added in API level 1
Send a
WARN log message and log the exception.Parameters
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
|---|---|
| msg | The message you would like logged. |
| tr | An exception to log |
public static int w (String tag, String msg)
Added in API level 1
Send a
WARN log message.Parameters
| tag | Used to identify the source of a log message. It usually identifies the class or activity where the log call occurs. |
|---|---|
| msg | The message you would like logged. |
public static int wtf (String tag, Throwable tr)
Added in API level 8
What a Terrible Failure: Report an exception that should never happen.
Similar to
wtf(String, String), with an exception to log.Parameters
| tag | Used to identify the source of a log message. |
|---|---|
| tr | An exception to log. |
public static int wtf (String tag, String msg)
Added in API level 8
What a Terrible Failure: Report a condition that should never happen.
The error will always be logged at level ASSERT with the call stack.
Depending on system configuration, a report may be added to the
DropBoxManager and/or the process may be terminated
immediately with an error dialog.Parameters
| tag | Used to identify the source of a log message. |
|---|---|
| msg | The message you would like logged. |
public static int wtf (String tag, String msg, Throwable tr)
Added in API level 8
What a Terrible Failure: Report an exception that should never happen.
Similar to
wtf(String, Throwable), with a message as well.Parameters
| tag | Used to identify the source of a log message. |
|---|---|
| msg | The message you would like logged. |
| tr | An exception to log. May be null. |
