Log usage (log. V, log. D, log. I, log. W, log. e)

 

When debugging code, we need to view the debugging information, so we need to use the android log class.

Common android. util. Log methods include:5Items:Log. V () Log. D () Log. I () log. W ()AndLog. E (). Corresponds to the first letterVerbose,Debug, info, warn, and error.

1. the debugging color of log. V isBlack, Any message will be output. Here v stands for verbose, which is usually used as log. V ("","");

2. The output color of log. D isBlueOnly the meaning of DEBUG debugging is output, but the upper-layer information is output, which can be selected through the logcat tag of ddms.

3. The output of log. I isGreenGenerally, the prompt message information does not output the information of log. V and log. D, but displays the information of I, W, and E.

4. log. W meansOrangeIt can be seen as a warning of warning. Generally, we need to optimize the android code and select it to output log. e information.

5. If log. e is red, you can think of error errors. Here, only red error messages are displayed. We need to carefully analyze these errors and view stack information.

Note: different printing methods are used with the (string tag, string MSG) parameter in a method. Tag indicates the tag of the printed information, and MSG indicates the information to be printed.

Below is a simple exampleLogdemo(Step by step ):

Step 1: Preparation (openLogcatWindows ).

StartEclipse, InWindow-> show ViewA dialog box is displayed. When we clickOKButton appears in the console windowLogcatWindows. For example:

Step 2: CreateAndroidProject, namedLogdemo.

Step 3:DesignUIInterface, we addButtonButtonLogLog information ).

Main. xmlThe Code is as follows:

 <? XML version = "1.0" encoding = "UTF-8"?> <Br/> <linearlayout xmlns: Android = "http://schemas.android.com/apk/res/android" <br/> Android: Orientation = "vertical" <br/> Android: layout_width = "fill_parent" <br/> Android: layout_height = "fill_parent" <br/> <textview <br/> Android: layout_width = "fill_parent" <br/> Android: layout_height = "wrap_content" <br/> Android: TEXT = "@ string/Hello" <br/> <button <br/> Android: id = "@ + ID/BT" <br/> Android: layout_width = "wrap_content" <br/> Android: layout_height = "wrap_content" <br/> Android: TEXT = "Presse me look log" <br/> </linearlayout>

Step 4: Design the main classLogdemo. JavaThe Code is as follows:

Public class logdemo extends activity {</P> <p> Private Static final string activity_tag = "logdemo"; <br/> private button Bt; <br/> Public void oncreate (bundle savedinstancestate) {<br/> super. oncreate (savedinstancestate); <br/> setcontentview (R. layout. main); <br/> // find the button resource through findviewbyid <br/> bt = (button) findviewbyid (R. id. BT); <br/> // Add Event Response <br/> BT. setonclicklistener (New button. onclicklistener () {<br/> @ override <br/> Public void onclick (view v) {<br/> log. V (logdemo. activity_tag, "this is verbose. "); <br/> log. D (logdemo. activity_tag, "this is debug. "); <br/> log. I (logdemo. activity_tag, "this is information"); <br/> log. W (logdemo. activity_tag, "this is warnning. "); <br/> log. E (logdemo. activity_tag, "this is error. "); <br/>}</P> <p >}); <br/>}</P> <p>}

Step
5: RunLogdemoProject, the effect is as follows:

When you click the button, the event is triggered. The following results are displayed in the logcat window:

This article from http://blog.csdn.net/Android_Tutor/archive/2009/12/26/5081713.aspx