Question

Hello there people of stack overflow, I have just started developing with android and have run into a bit of a problem. I am trying to run a very simple app that has a single button, which when clicked updates the text to the current time. However, the app does not even start up. I am following a book. “Beginning Android 2”, and am just learning about XML layouts. The same app worked without an XML layout, so it may be something to do with my xml.

Anyways, I’m running it on a droid 2, if that helps.

Heres the codes.

package apt.tutorial;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import java.util.Date;

public class FirstApp extends Activity implements View.OnClickListener {
    /** Called when the activity is first created. */
    Button btn;

    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);

        setContentView(R.layout.main);

        btn = (Button)findViewById(R.id.button);
        btn.setOnClickListener(this);
        updateTime();
    }

    public void onClick(View view) {
        updateTime();
    }

    private void updateTime() {
        btn.setText(new Date().toString());
    }
}

And the XML file

<Button xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/button"
    android:text=""
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    />

Thanks in advance.

Answer 1

You should enclose the button inside a layout (linear, relative, etc):

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" >
    <Button xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/button"
    android:text=""
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    />
</LinearLayout>