Here are some quick tips that will come in handy when developing an android application.
S.No | Issue | Solution |
1. | How to remove focus for an EditText control? (When a new screen is launched with EditText, keypad appears automatically hiding the screen layout). | Set android:focusableInTouchMode="true" in the layout where the EditText is coded to remove the automatic setting of focus. |
2. | How to add an image in a Button control? | Set android:drawableright=”drawable/image1” in the Button layout to add the image to the right and android:drawableleft =”drawable/image1” to add the image to the left. |
3. | How to remove the background from a button and make it transparent? | Set android:background=”@android: color/transparent” in the Button layout |
4. | How to allow signed numbers in EditText? | Set android:inputType=”numberDecimal/numberSigned” in the EditText layout. |
5. | How to set gradient colour for a button? | Create an xml with shape object and give the gradient colours <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle"> <gradient android:endColor="#9BBB59” android:startColor="#4F6228” android:angle="90" /> </shape> Include this xml in the drawable and give as background for the button. |
6. | How to set a common background for 2 or more controls like a Button , Textview and EditText? | Use a <Framelayout> and set the background colour or image in the layout. Include the controls inside the layout. |
7. | How to manage multiple screen layouts in a single activity? | Use <ViewFlipper> and flip the screen layouts in the code. |
8. | How to declare global variables to be used by all activities in a package? | Create a class file that extends Application and declare the variable in it. In the other files, the variable can be accessed as follows: Variable1 = ((class file name) getApplication()). Variable name. |
9. | How to make the screen or part of the screen scrollable? | Wrap the layout to be scrolled in a ScrollView using <ScrollView> tag. Remember to have just one layout (like RelativeLayout or LinearLayout) or control (like TextView or Button) inside the ScrollView. |
10. | How to display HTML text in a button? | Button.setText(Html.fromHtml(sText)) where sText is the string containing the text in HTML format. |
Below is the list of some frequent issues encountered while testing an android application.
S.No | Issue | Solution |
1. | NumberFormatException | This may occur due to several reasons and one of the reasons is setting the value of an EditText control with inputType as signed decimal, to spaces. For ex: If an EditText control has inputType defined as below. android:inputType=”numberDecimal/numberSigned” If you set the value of the above EditText to spaces as below mEditText.setText(“ “), it will throw a NumberFormatException. Set the EditText control’s inputType to "numberSigned" only if you need the control to accept negative value, otherwise set it to just "numberDecimal". |
2. | ‘Window leaked error message’ when using an AlertDialog. | This error message will be thrown if the dialog is not dismissed (Dialog.dismiss()) in the onClick() method. |
3. | WARNING: Application does not specify an API level requirement! | In the Android Manifest file set the minimum SDK version required as below. <uses-sdk android:minSdkVersion=”3”/> |
