Why doesn't “System.out.println” work in Android?

Question

I want to print something in console, so that I can debug it. But for some reason, nothing prints in my Android application.

How do I debug then?

Answer 1

There is no place on your phone that you can read the System.out.println();

Instead, if you want to see the result of something either look at your logcat/console window or make a Toast or a Snackbar (if you're on a newer device) appear on the device's screen with the message :) That's what i do when i have to check for example where it goes in a switch case code! Have fun coding! :)

Answer 2

Use the Log class. Output visible with LogCat

Answer 3

I dont having fancy IDE to use LogCat as I use a mobile IDE.

I had to use various other methods and I have the classes and utilties for you to use if you need.

1. class jav.android.Msg. Has a collection of static methods. A: methods for printing android TOASTS. B: methods for popping up a dialog box. Each method requires a valid Context. You can set the default context.

2. A more ambitious way, An Android Console. You instantiate a handle to the console in your app, which fires up the console(if it is installed), and you can write to the console. I recently updated the console to implement reading input from the console. Which doesnt return until the input is recieved, like a regular console. A: Download and install Android Console( get it from me) B: A java file is shipped with it(jav.android.console.IConsole). Place it at the appropriate directory. It contains the methods to operate Android Console. C: Call the constructor which completes the initialization. D: read<*> and write the console. There is still work to do. Namely, since OnServiceConnected is not called immediately, You cannot use IConsole in the same function you instantiated it.

3. Before creating Android Console, I created Console Dialog, which was a dialog operating in the same app to resemble a console. Pro: no need to wait on OnServiceConnected to use it. Con: When app crashes, you dont get the message that crashed the app.

Since Android Console is a seperate app in a seperate process, if your app crashes, you definately get to see the error. Furthermore IConsole sets an uncaught exception handler in your app incase you are not keen in exception handling. It pretty much prints the stack traces and exception messages to Android Console. Finally, if Android Console crashes, it sends its stacktrace and exceptions to you and you can choose an app to read it. Actually, AndroidConsole is not required to crash.

Edit Extras I noticed that my while APK Builder has no LogCat; AIDE does. Then I realized a pro of using my Android Console anyhow.

1. Android Console is design to take up only a portion of the screen, so you can see both your app, and data emitted from your app to the console. This is not possible with AIDE. So I I want to touch the screen and see coordinates, Android Console makes this easy.

2. Android Console is designed to pop up when you write to it.

3. Android Console will hide when you backpress.

Answer 4

Yes it does. If you're using the emulator, it will show in the Logcat view under the System.out tag. Write something and try it in your emulator.

Answer 5

Of course, to see the result in logcat, you should set the Log level at least to "Info" (Log level in logcat); otherwise, as it happened to me, you won't see your output.

Answer 6

it is not displayed in your application... it is under your emulator's logcat