You need to override onSaveInstanceState(Bundle savedInstanceState)
and write the application state values you want to change to the Bundle
parameter like this:
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
// Save UI state changes to the savedInstanceState.
// This bundle will be passed to onCreate if the process is
// killed and restarted.
savedInstanceState.putBoolean("MyBoolean", true);
savedInstanceState.putDouble("myDouble", 1.9);
savedInstanceState.putInt("MyInt", 1);
savedInstanceState.putString("MyString", "Welcome back to Android");
// etc.
}
The Bundle is essentially a way of storing a NVP ("Name-Value Pair") map, and it will get passed in to onCreate()
and also onRestoreInstanceState()
where you would then extract the values from activity like this:
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
// Restore UI state from the savedInstanceState.
// This bundle has also been passed to onCreate.
boolean myBoolean = savedInstanceState.getBoolean("MyBoolean");
double myDouble = savedInstanceState.getDouble("myDouble");
int myInt = savedInstanceState.getInt("MyInt");
String myString = savedInstanceState.getString("MyString");
}
Or from a fragment.
@Override
public void onViewStateRestored(@Nullable Bundle savedInstanceState) {
super.onViewStateRestored(savedInstanceState);
// Restore UI state from the savedInstanceState.
// This bundle has also been passed to onCreate.
boolean myBoolean = savedInstanceState.getBoolean("MyBoolean");
double myDouble = savedInstanceState.getDouble("myDouble");
int myInt = savedInstanceState.getInt("MyInt");
String myString = savedInstanceState.getString("MyString");
}
You would usually use this technique to store instance values for your application (selections, unsaved text, etc.).
I discovered that this can all be done in one file fairly easily. Put something like the following code in a file named custom_button.xml
and then set background="@drawable/custom_button"
in your button view:
<?xml version="1.0" encoding="utf-8"?>
<selector
xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_pressed="true" >
<shape>
<gradient
android:startColor="@color/yellow1"
android:endColor="@color/yellow2"
android:angle="270" />
<stroke
android:width="3dp"
android:color="@color/grey05" />
<corners
android:radius="3dp" />
<padding
android:left="10dp"
android:top="10dp"
android:right="10dp"
android:bottom="10dp" />
</shape>
</item>
<item android:state_focused="true" >
<shape>
<gradient
android:endColor="@color/orange4"
android:startColor="@color/orange5"
android:angle="270" />
<stroke
android:width="3dp"
android:color="@color/grey05" />
<corners
android:radius="3dp" />
<padding
android:left="10dp"
android:top="10dp"
android:right="10dp"
android:bottom="10dp" />
</shape>
</item>
<item>
<shape>
<gradient
android:endColor="@color/blue2"
android:startColor="@color/blue25"
android:angle="270" />
<stroke
android:width="3dp"
android:color="@color/grey05" />
<corners
android:radius="3dp" />
<padding
android:left="10dp"
android:top="10dp"
android:right="10dp"
android:bottom="10dp" />
</shape>
</item>
</selector>
Best Answer
With Android M (api level 23) you can achieve this from theme with
android:windowLightStatusBar
attribute.Edit :
Just as Pdroid mentioned, this can also be achieved programatically: