Logcat window in Android Studio

Logcat Window is the place where various messages can be printed when an application runs. Suppose, you are running your application and the program crashes, unfortunately. Then, Logcat Window is going to help you to debug the output by collecting and viewing all the messages that your emulator throws. So, this is a very useful component for the app development because this Logcat dumps a lot of system messages and these messages are actually thrown by the emulator.

This means, that when you run your app in your emulator, then you will see a lot of messages which include all the information, all the verbose messages, all the errors that you are getting in your application. Suppose, an application of about 10000 lines of code gets an error. So, in that 10000 line codes, to detect the error Logcat helps by displaying the error messages.

Errors in different modules and methods can be easily detected with the help of Logcat window.

Using logcat window:

The logcat prints error using a Log Class. The class which is used to print the log messages are actually known as a Log Class. So, this class is responsible to print messages in the Logcat terminal. There are lots of methods that are present in the log class:



v(String, String) verbose
d(String, String) debug
i(String, String) information
w(String, String) warning
e(String, String) error

All these methods contains two parameters in it. First and second both are the string. When you print the log messages with these different methods, then you will get a corresponding color according to the method.

Method Output will be printed in 
verbose black
debug blue
information green
warning red
error orange

Verbose method is of very lesser priority and error is of higher priority. Thus, the method’s priority increases from verbose to error.

Syntax

// for verbose
Log.v(“TAG”, “MESSAGE”);

// for debug
Log.d(“TAG”, “MESSAGE”);

// for information
Log.i(“TAG”, “MESSAGE”);

// for warning
Log.w(“TAG”, “MESSAGE”);

// for error
Log.e(“TAG”, “MESSAGE”);

For Example: A verbose log message can be written as

Log.v(“MainActivity”, “We are under the Main Activity”);

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