Common Android development problems and their solution
1. Common Android development problems and their solution
Things are not always working as they should during your Android development. This section gives an overview over typical problems and how to solve them.
Several users report
that they get the following errors:
To solve any of these errors, go to the project menu and select → .
If you have library projects, make sure to clean them too.
-
Project ... is missing required source folder: 'gen'
-
The project could not be built until build path errors are
resolved.
-
Unable to open class file R.java.
To solve any of these errors, go to the project menu and select → .
If you have library projects, make sure to clean them too.
During start or during execution of your application, your
application stops. In
the
LogCat
view
you see the message:
android.content.ActivityNotFoundException :
Unable to find explicit activity class; have you declared this
activity in your AndroidManifest.xml?
Check in this case if you declared your activity in the
Check in this case if you declared your activity in the
AndroidManifest.xml
file.
The communication with the emulator or your Android device
might have problems. This communication is handled by the Android
Debug Bridge (adb).
Eclipse allows to reset the adb in case this causes problems. Select therefore the DDMS perspective via → → →
To restart the adb, select the "Reset adb" in the Device
Eclipse allows to reset the adb in case this causes problems. Select therefore the DDMS perspective via → → →
To restart the adb, select the "Reset adb" in the Device
View.
The
LogCat
view
shows you the log messages of your Android device and helps
you to
analyze
problems. For example Java exceptions in your
program would be
shown
here. To open this view, select
→ → → → .
If Android complains that you cannot use Java7 select your
right-click on your project
and select the
Java Compiler
entry. Ensure that Java 1.5 or Java 1.6 is used. You may have to
select the
Enable project specific settings
checkbox.
Sometimes Eclipse complains that a file, e.g.
R.layout.main
cannot be found. Check in your source code that you did not import
android.R. An
android.R
import will prevent Eclipse from finding your
R
file.
Android provides nice editors to edit
Android resource files,
unfortunately these editor are not always automatically
used due to
bugs
in the ADT. If that happens, you can open this editor manually.
Right-click on
your menu file and select
→ .
If your emulator does not start, make sure that the
android-sdk
version is in a path without any spaces in the path name.
If you face timeout issues during deployment you can increase the
default timeout in the Eclipse preferences. Select
→ → →
and increase the
ADB connection timeout (in ms)
value.
Sometimes the emulator will refuse to install an application
with the error
message: INSTALL_FAILED_INSUFFICIENT_STORAGE.
An Android virtual device provides by default only 64M for the storaging Android applications. You can clean your installed application by re-starting the emulator and selecting the Wipe user data " flag.
Alternatively you can set the data partition size. If you press edit on the AVD, you can set the
An Android virtual device provides by default only 64M for the storaging Android applications. You can clean your installed application by re-starting the emulator and selecting the Wipe user data " flag.
Alternatively you can set the data partition size. If you press edit on the AVD, you can set the
Ideal size of data partition
property via the
button.
If you get the error message
Debug Certificate expired
switch
to the folder which contains the Android AVD, e.g.
.android
under
Linux and delete the
debug.keystore
file. This file is only
valid
for a year and if not present, Eclipse
will regenerate the
password.
The
@Override
annotation was introduced in Java 1.6. If you receive
an
error message
for
@Override, change the Java compiler level to Java 1.6. To do this,
right-click
on the
project, select
→ →
and select
1.6
in the drop-down box.
Java requires that classes which are not part of the standard
Java
Language are either fully qualified or declared via imports.
If you see an error message with the XX cannot be resolved to a variable text, right-click in your
If you see an error message with the XX cannot be resolved to a variable text, right-click in your
Editor
and select
→
to important required packages.
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