Hi, I am developing a simple two view app. I am overriding the onKeyPressed to make the activity go into background when back key is pressed, instead of destroying it. Now when I am on first view and I sent the activity to background(using back key) , on again launching the app, the first view appears correctly, but when I am on second view and I send the activity to background, When I launch the app a Black Screen Appears. I am not able to find a solution to it. Please help. The relevant source code is:
1. main.xml : <?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/ android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <RelativeLayout android:id="@+id/firstview" android:layout_height = "fill_parent" android:layout_width = "fill_parent" android:visibility="visible" > <TextView android:id="@+id/firstviewet" android:layout_width="fill_parent" android:layout_height = "60px" android:layout_alignParentTop="true" android:layout_alignParentLeft="true" android:layout_marginTop="20px" android:text="You are in first view" /> <Button android:id="@+id/firstviewbutton" android:layout_width="fill_parent" android:layout_height = "wrap_content" android:layout_below="@id/firstviewet" android:layout_marginTop="20px" android:text="Press Me" android:layout_alignParentLeft="true" /> </RelativeLayout> <RelativeLayout android:id="@+id/secondview" android:layout_height = "fill_parent" android:layout_width = "fill_parent" android:visibility="invisible" > <TextView android:id="@+id/secondviewet" android:layout_width="fill_parent" android:layout_height = "60px" android:layout_alignParentTop="true" android:layout_alignParentLeft="true" android:text="You are in second view" /> <Button android:id="@+id/secondviewbutton" android:layout_width="fill_parent" android:layout_height = "wrap_content" android:layout_alignParentBottom="true" android:layout_alignParentLeft="true" /> </RelativeLayout> </FrameLayout> 2. BackgroundActivity.java: package com.octro.demo.backgroundapp; import android.app.Activity; import android.os.Bundle; import android.util.Log; import android.view.KeyEvent; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class BackgroundActivity extends Activity { AppState currentState; BackgroundAppHelper bgdAppHelper = null; View firstView, secondView; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //setContentView(R.layout.main); bgdAppHelper = BackgroundAppHelper.getInstance(); //firstView = findViewById(R.id.firstview); //secondView = findViewById(R.id.secondview); if(bgdAppHelper.getCurrentState() == null) bgdAppHelper.startBgdActivityHandling(this); else bgdAppHelper.setAppState(); } public void displayMainView() { setContentView(R.layout.main); } public View getFirstView() { if(firstView == null) firstView = findViewById(R.id.firstview); return firstView; } public View getSecondView() { if(secondView == null) secondView = findViewById(R.id.secondview); return secondView; } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { // TODO Auto-generated method stub if(keyCode == KeyEvent.KEYCODE_BACK) { if(bgdAppHelper.backKeyPressed()) return true; } return super.onKeyDown(keyCode, event); } @Override protected void onStop() { // TODO Auto-generated method stub Log.v("onStop", "in on stop method"); super.onStop(); } @Override protected void onDestroy() { // TODO Auto-generated method stub Log.v("onDestroy", "in on destroy method"); super.onDestroy(); } public boolean backKeyPressed() { moveTaskToBack(true); return true; } } 3. BackgroundAppHelper.java : package com.octro.demo.backgroundapp; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class BackgroundAppHelper { private AppState currentState; private BackgroundActivity backgroundActivityObj = null; private View firstView = null; private View secondView = null; private Button button = null; private static BackgroundAppHelper backgroundAppHelper = null; private BackgroundAppHelper() { } public static BackgroundAppHelper getInstance() { if(backgroundAppHelper == null) backgroundAppHelper = new BackgroundAppHelper(); return backgroundAppHelper; } public void startBgdActivityHandling(BackgroundActivity bgAObj) { if(backgroundActivityObj == null) backgroundActivityObj = bgAObj; startFirstView(); } private void startFirstView() { backgroundActivityObj.displayMainView(); if(firstView == null) firstView = backgroundActivityObj.getFirstView(); if(currentState == null) currentState = new AppState(); currentState.appState = EAppState.FirstView; button = (Button)firstView.findViewById(R.id.firstviewbutton); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub startSecondView(); } }); } public void setAppState() { if(currentState.appState == EAppState.SecondView) { firstView.setVisibility(View.GONE); secondView.setVisibility(View.VISIBLE); backgroundActivityObj.displayMainView(); } } public boolean backKeyPressed() { return backgroundActivityObj.backKeyPressed(); } private void startSecondView() { if(secondView == null) secondView = backgroundActivityObj.getSecondView(); firstView.setVisibility(View.GONE); secondView.setVisibility(View.VISIBLE); currentState.appState = EAppState.SecondView; } public AppState getCurrentState() { return currentState; } } 4. AppState.java package com.octro.demo.backgroundapp; public class AppState { EAppState appState; } 5. EAppState.java package com.octro.demo.backgroundapp; public enum EAppState { FirstView(0), SecondView(1); int eAppState; EAppState(int value) { eAppState = value; } } -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
