Develop Reference

Force Main-Layout to Inflate

I'll try another shot. Hopefully now i get the answere i totally Need.
Just imagine:
I have a widget which calls(after onClick) a blank activity with no hardcoded code, just a Relative Layout with some views.(Layout provided by XML-layout-file).
My Activity:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.myLayout);
When i add a for-loop to the onCreate-Method which adds 50 Buttons(take no care about layoutparams, orientation and so on). Just 50 simply Buttons
Like:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.myLayout);
for(int i = 0; i<50; i++) {
Button btn = new Button(this);
myLayout.add(btn);
}
I recognize that he only Shows the activity on the Screen until he finished to add all the Buttons.
My Question is: How can i prevent this!? How can i Show up the Activity with the Content from the XML-layout file and then(ONLY then) add one Button after another to the Layout.
Is this possible? If so, do i neew to redraw the whole activity and so on. Please give me advise to my issue.

Show white screen until layout is completely constructed

My problem is that I have complicated layout, and when my application starts, I see how every view is adding to layout. I see my custom window title bar construction too. I see empty custom window title, with gradient background on start, and then 1 - 2 sec later I see completed window title with my views.
requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
setContentView(R.layout.main);
getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.title);
Is there simple way to show white screen, until my activity and custom title bar will be completely constructed?
The main trouble is that I cant start application with no title, and then add custom window title.
Only solution I know is splash screen, but it is too complicated for just this small task.

Use an asynctask like this:
private class LoadingMyView extends AsyncTask<void, void, int> {
protected void onPreExecute ()
{
requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
setContentView(R.layout.main);
getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.title);
//show whiteView
}
protected int doInBackground() {
return 0;
}
protected void onPostExecute(int result) {
//Hide white View
}
}
Note: I didnt test the code but i think more or less is ok
AsyncTask

How to change color of backGround on app load(onCreate())?

I am trying to change r=the color of the back ground on app load. For this I have used something like this :
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final View view= new View(getApplicationContext());
view.post(new Runnable() {
#Override
public void run() {
view.setBackgroundColor(Color.BLACK);
}
});
addListenerOnButton();
}
This does not work. See the emulator screen shot below :
As you can see the back ground color is still white . Any ideas on what i can do to rectify this ?

Simple. Try this way.
this.findViewById(android.R.id.content).setBackgroundColor(Color.BLACK);
For ex:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
this.findViewById(android.R.id.content).setBackgroundColor(Color.BLACK);
}
Here findViewById(android.R.id.content) will return ContentView of current activity. Then you can set background for this view.
I hope this will help you.

First of all, view.post() is not necessary, because onCreate() already runs in the UI thread. Secondly, you are creating a View and setting the background of it, but you never set the view to anywhere, it's just an Object that never gets drawn. There are 2 solutions:
either:
View view= new View(this);
view.setBackgroundColor(Color.BLACK);
setContentView(view);
or, probably better:
setContentView(R.layout.activity_main);
View view = findViewById(R.id.root_laout); // set the root_layout in the layout xml file
view.setBackgroundColor(Color.BLACK);

This should do the trick:
this.findViewById(android.R.id.content).setBackgroundColor(Color.BLACK);

Clear previous View and show new View on button click in the same Activity

I have created an activity with two buttons at the top. One button to show "SMS Logs" and second to show "Call Logs".
On clicking "SMS Logs" button, i am dynamically creating textviews and linear layout to show sms logs.
On Clicking "Call Logs", i am dynamically creating another textviews and linear layout to show call logs.
But the problem is that, once if we click "sms log" button and then we click "call log" button, the previously created linear layouts are not removed and the both(previous layouts and the current layouts) are shown simultaneously.
But i want that the previous layouts should be removed on clicking the second button.
Which function, should i use to remove the previous viewgroups or the layouts. Tell me if you need to read my class file.
Edit:
This is my Activity's code,
public class General extends Activity
{
String phone, message;
TextView Logs;
View layout, callLayout;
TextView data, callData, line, callLine;
Button smsLog, callLog;
LinearLayout ll, callll;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.general_main);
Logs = (TextView)findViewById(R.id.Logs);
layout = findViewById(R.id.layout);
callLayout = findViewById(R.id.layout);
smsLog = (Button)findViewById(R.id.smsLogs);
callLog = (Button)findViewById(R.id.callLogs);
smsLog.setOnClickListener(new View.OnClickListener() {
public void onClick(View v)
{
callLayout.setVisibility(View.GONE);
ll = new LinearLayout(getApplicationContext());
ll.setOrientation(LinearLayout.VERTICAL);
data = new TextView(getApplicationContext());
data.setText("First Line");
data.setTextColor(Color.YELLOW);
line = new TextView(getApplicationContext());
line.setText("Second Line");
((ViewGroup) ll).addView(data);
((ViewGroup) layout).addView(line);
((ViewGroup) layout).addView(ll);
}
});
callLog.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
layout.setVisibility(View.GONE);
callll = new LinearLayout(getApplicationContext());
callll.setOrientation(LinearLayout.VERTICAL);
callData = new TextView(getApplicationContext());
callLine = new TextView(getApplicationContext());
callData.setText("Third Line");
callLine.setText("Fourth Line");
((ViewGroup) callll).addView(callData);
((ViewGroup) callLayout).addView(callLine);
((ViewGroup) callLayout).addView(callll);
}
});
}
}
I have removed the extra code and made it simple to understand.

You can use FrameLayout to solve your problem. But I recommend you to use tabview.Here is the link that demonstrates how to develop tabbed applications.Good Luck

You could implement a TabView.
But having your current setup just change the visibility of one view group to GONE and the other to VISIBLE.
GONE will make the view invisible and it won't take up any space anymore.
EDIT based on the code added to the question
Both your layout and callLayout are using the same XML view. Implement 2 identical views in your xml and keep one visible and one gone. This way when you set layout or callLayout visibility to GONE they are 2 different ones not the same. So your onClick() will have something like this:
for smsLog:
layout.setVisibility(View.GONE);
callLayout.setVisibility(View.VISIBLE);
for callLog:
callLayout.setVisibility(View.GONE);
callLayout.setVisibility(View.VISIBLE);

CheckBoxes in ListView disappear when the screen rotates

What my application first does is it loads ListView whose items have invisible CheckBoxes by setting its visibility View.Gone. When the user tabs a menu button then it will turn on and off the CheckBox visibility and some other layouts. Below is the code, I removed some unnecessary parts:
private void editmodeSwitch(boolean flag){
// get topbar, bottombar, and bottombar2
LinearLayout topbar = (LinearLayout) findViewById(R.id.task_topbar_linearLayout);
LinearLayout bottombar = (LinearLayout) findViewById(R.id.task_bottombar1_linearlayout);
LinearLayout bottombar2 = (LinearLayout) findViewById(R.id.task_bottombar2_linearlayout);
if(flag){
isEditmodeOn = true;
// make topbar and bottombar2 visilble, but bottombar gone
topbar.setVisibility(View.VISIBLE);
bottombar.setVisibility(View.GONE);
bottombar2.setVisibility(View.VISIBLE);
// make checkboxes visible in listview visible as well
for(int i=0; i<listView.getChildCount(); i++){
LinearLayout ll = (LinearLayout) listView.getChildAt(i);
CheckBox cb = (CheckBox) ll.findViewById(R.id.task_row_checkBox1);
cb.setVisibility(View.VISIBLE);
}
}
else{
isEditmodeOn = false;
topbar.setVisibility(View.GONE);
bottombar.setVisibility(View.VISIBLE);
bottombar2.setVisibility(View.GONE);
// set each checkbox false and its visibility gone
for(int i=0; i<listView.getChildCount(); i++){
LinearLayout ll = (LinearLayout) listView.getChildAt(i);
CheckBox cb = (CheckBox) ll.findViewById(R.id.task_row_checkBox1);
cb.setVisibility(View.GONE);
cb.setChecked(false);
}
}
}
It works fine but the problem is the application doesn't work when the screen rotates(changes the screen orientation). Everything worked fine as it displayed some layouts but only CheckBoxes in list items. Below is the code inonCreate()`:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.task_layout);
initialize();
loadDB();
updateListAdapter(list_title, list_date);
// in case of screen rotation
if(savedInstanceState != null){
isEditmodeOn = savedInstanceState.getBoolean(EDITMODE_CHECK);
isItemChecked = savedInstanceState.getBoolean(ITEM_CHECK);
if(isEditmodeOn){
if(!isItemChecked){
Log.i(tag, "item NOT checked");
editmodeSwitch(true);
} else{
//this is something different so please don't mind
deditmodeSwitch(savedInstanceState.getBooleanArray(LIST_CB_CHECK));
}
}
}
}
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
// save values for rotation
outState.putBoolean(EDITMODE_CHECK, isEditmodeOn);
outState.putBoolean(ITEM_CHECK, isItemChecked);
outState.putBooleanArray(LIST_CB_CHECK, list_cb_check);
}
#Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
Log.i(tag, "you're in onRestoreInstanceState()");
// in case of screen rotation
if(savedInstanceState != null){
isEditmodeOn = savedInstanceState.getBoolean(EDITMODE_CHECK);
isItemChecked = savedInstanceState.getBoolean(ITEM_CHECK);
if(isEditmodeOn){
if(!isItemChecked){
Log.i(tag, "item NOT checked");
editmodeSwitch(true);
} else{
// this is for something else so please ignore this part
editmodeSwitch(savedInstanceState.getBooleanArray(LIST_CB_CHECK));
}
}
}
What I guessed is the ListView is being loaded at the end. Therefore, even if the code in onCreate() makes CheckBoxes visible, the CheckBoxes will become invisible again as its initialization in xml will do so. However, I'm stuck here and need your advice to solve this problem. Can anyone help me?
Just in case, below is the checkbox code of layout xml file for getview.
<CheckBox android:id="#+id/task_row_checkBox1" android:gravity="right"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:visibility="gone"
/>

Override onSaveInstanceState for saving value on screen rotation and onRestoreInstanceState as:
protected void onCreate(Bundle savedInstanceState) {
if(null != savedInstanceState)
{
Boolean IntTest = savedInstanceState.getBoolean("ITEM_CHECK");
Boolean StrTest = savedInstanceState.getBoolean("ITEM_CHECK");
Log.e(TAG, "onCreate get the savedInstanceState+IntTest="+IntTest+"+StrTest="+StrTest);
}
}
#Override
public void onSaveInstanceState(Bundle savedInstanceState) {
// Save away the CheckBoxes states, so we still have it if the activity
// needs to be killed while paused.
savedInstanceState.putBoolean(EDITMODE_CHECK, 0);
savedInstanceState.putBoolean(ITEM_CHECK, 0);
super.onSaveInstanceState(savedInstanceState);
Log.e(TAG, "onSaveInstanceState");
}
#Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
Boolean IntTest = savedInstanceState.getBoolean(EDITMODE_CHECK);
Boolean StrTest = savedInstanceState.getBoolean(ITEM_CHECK);
Log.e(TAG, "onRestoreInstanceState+IntTest="+IntTest+"+StrTest="+StrTest);
}

Similar to how you override onCreate, you can override onConfigurationChanged(...) which you can setup to run when the screen changes orientation.
In order for OnConfigurationChanged(...) to be trigger when the screen rotates, you need to to edit your manifest and put that relationship/rule in.
It's easy to do but takes a bit of explaining and it was answered before in this question:
Activity restart on rotation Android
Edit: Here is the dev guide on how to handle configuration changes
http://developer.android.com/guide/topics/resources/runtime-changes.html
Edit #2: First, let me suggest using Imran's solution. It follows the Developer Guide better and the end results will be the same.
Now, for the onConfigurationChanged solution.
Look at what you are doing with your onCreate:
1) Set the view. (Checkboxes are hidden at this point. Right?)
2) Call your DB and determine if you should display checkboxes (edit mode)
3) Make all the checkboxes visible.
Now, onConfigurationChanged also calls setContentView, at which point all your checkboxes are hidden again. So you need to repeat the process of making your checkboxes visible (#3 above). You probably don't need to repeat step #2 because the value should be retained, but I'm not sure how the logic of your app works, so you may need to re-do step #2.
Does that make sense?

Based on my experience, getview seems to be triggered at the end and it was why 'onRestoreInstanceState()' and 'onConfigurationChanged()' could not make it as getview will reset my checkboxes invisible as initialization in the layout xml file.
Therefore, the only solution I could find out was I must control them in getview for the answer.