Why do I get an error while trying to set the content of a tabspec in android?
I have an android activity in which I'm using tabs.
public class UnitActivity extends TabActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.unit_view);
TabHost tabHost = getTabHost();
TabSpec spec;
spec = tabHost.newTabSpec("controls");
spec.setIndicator("Control");
spec.setContent(R.layout.unit_control);
tabHost.addTab(spec);
spec = tabHost.newTabSpec("data");
spec.setIndicator("Data");
spec.setContent(R.layout.unit_data);
ta开发者_如何学编程bHost.addTab(spec);
}
}
However when I run the program it crashes with the error: "Could not create tab content because could not find view with id 2130903042". I don't understand what the problem is because R.layout.unit_data refers to a layout file in my resource directory (res/layout/unit_data.xml)
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TableLayout
android:stretchColumns="*"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Spinner android:id="@+id/unit_num"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:prompt="@string/choose_unit"/>
<TableRow android:padding="2dp">
<TextView
android:gravity="right"
android:padding="5dp"
android:text="@string/Power"/>
<TextView android:id="@+id/unit_power"
android:layout_span="3"
android:gravity="center"
android:padding="5dp"
android:background="@android:color/white"
android:textColor="@android:color/black"
android:text="AUTO"/>
</TableRow>
...
</TableLayout>
</ScrollView>
as far as I can tell unit_data.xml is well formed and I've even referenced it successfully in another activity
class UnitData extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.unit_data);
Toast.makeText(this, "Hi from UnitData.onCreate", 5);
}
}
which does not give an error and renders the layout just fine.
What's going on? Why can't I reference this layout when creating a tab?
While Activity.setContentView takes an id of a Layout, TabSpec.setContent takes an id of a View. This means you need to pass an id that looks like R.id.something
and not R.layout.something
.
To solve your particular problem, give the top level view in your layout a view id:
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/unit_data"> <!-- NOTE THE CHANGE -->
...
</ScrollView>
and update your source:
public class UnitActivity extends TabActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.unit_view);
TabHost tabHost = getTabHost();
TabSpec spec;
spec = tabHost.newTabSpec("controls");
spec.setIndicator("Control");
spec.setContent(R.id.unit_control); // NOTE THE CHANGE
tabHost.addTab(spec);
spec = tabHost.newTabSpec("data");
spec.setIndicator("Data");
spec.setContent(R.id.unit_data); // NOTE THE CHANGE
tabHost.addTab(spec);
}
}
For more information, see the tab examples in the ApiDemos:
If you have your tab layout in a different file, you have to inflate the XML.
spec = tabHost.newTabSpec("data");
spec.setIndicator("Data");
// Add the layout to your tab view
getLayoutInflater().inflate(R.layout.unit_data, tabHost.getTabContentView(), true);
spec.setContent(R.id.unit_data);
tabHost.addTab(spec);
You also have to use LayoutInflater after TabHost
LayoutInflater.from(this).inflate(R.layout.unit_data, tabHost.getTabContentView(), true);
I also got stuck with this and finally figure it out.
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