TextView txtOtherMatches = (TextView) dialog.findViewById(R.id.txtOtherMatches);
txtOtherMatches.setText("Other Matches");
i m getting this error while running application and i m just assigning simple text to Textview at run time .....
java.lang.NullPointerException
Make sure your TextView in the xml has exactly the same id: android:id="#+id/txtOtherMatches"
Check that you don't have more than one res/layout folder (e.g., layout-normal, layout-large or layout-land) and, if you do, make sure that your TextView is present in the layourt corresponding to your device/emulator
Check that it was added to the current View (most probably, through some ViewGroup)
If everything else fails, clean the Eclipse project and rebuild
txtOtherMatches is probably null because it doesn't exist in the current view.When you use findViewById the view must be in the "contentview" you've set with setContentView, or added later tot the view. You can't find any "random" view that has an ID somewhere, it must actually be "present" in your current view.
If the view is NOT in the xml you're using already, but somewhere else in one of your xmls, you must use an inflater to get the View, and add it with View.add()
It would be helpfull if you provide a few more lines before that one.
But my guess is Nanne is right.
Try to add a safety check:
(this wouldn't change the code flow)
if(txtOtherMatches == null) {
throw new NullPointerException("darn, the R.id.txtOtherMatches is not in the dialog")
}
(on the other hand Nanne mistakenly mentions 'current view' while I'm sure he meant the 'dialog' view.
Put some more meat if you need further assistance ;)
Related
Im using Android Studio, trying set text to Text View but every time i do this
TextView test = (TextView) findViewById(R.id.testView);
test.setText("fds");
on Android Studio i see Cannot resolve symbol 'setText'.
Can someone tell me what im doing wrong?
setText() will accept String which you have passed, so there is no issue in that.
One possible reason for this might be you have not written your code inside onCreate() or onCreateView().
If it is Activity you need to use these lines after setContentView() in onCreate().
If it is Fragment you need to use these lines after inflating your view in onCreateView().
Second reason, you might be having one more test variable of different type like String or something else
I used to do alot of Flash Actionscript and now I am getting into Android. Is there something in the Android API that is similar to duplicateMovieClip() in Actionscript? I'm sure there is probably a way to write such a method, but I am wondering if there are any existing shortcuts.
For example, say I have an ImageView, TextView, or other kind of View Object on screen and I want to have a button to click which will make a duplicate of some object on screen.
If you don't mind my asking, why do you need something like duplicateMovieClip()?
To answer the question, Android doesn't have a notion of the AS2 duplicateMovieClip(). Much like in AS3 (which also didn't have duplicateMovieClip()) you'll have to implement your own cloning method. Java does have an unimplemented '.clone()' method as part of every Java object, so if there's a particular View you would like to clone you might be able to implement your cloning there by
Overriding the clone method.
I think what you'd probably end up doing instead is doing something more akin to instantiating from the Library by making small view layouts in xml and inflating them using the Inflater tools.
View result = null;
// where pContext is a context object, either supplied by the application
// or just by the current Activity (if available)
LayoutInflater inflater = (LayoutInflater) pContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
// where id is the layout id such as R.layout.myclonableview.
// where pRoot is the parent container for the new result.
// where pAttachToRoot is whether to immediately inflate the new view into the root.
result = inflater.inflate(id, pRoot, pAttachToRoot);
// Now "clone" your old view by copying relevant fields from the old one to the
// one stored in result
I have a bunch of code in a routine that looks a bit like this:
a.setContentView(R.layout.myLayout);
textview t1 = (TextView) a.findViewById(R.id.mylayout_t1);
t1.setText("Hello")
t1.setTypeface(font);
t1.setTextColor(colour);
t1.setTextSize(fontSize);
textview t2 = (TextView) a.findViewById(R.id.mylayout_t2);
t2.setText("Hello Again")
t2.setTypeface(font);
t2.setTextColor(colour);
t2.setTextSize(fontSize);
The problem I'm having is that before when the routine is called, the layout is done with all the fonts at the default font/size/colour and then they quickly change to the specified values, which is not very pleasant on the eye.
Is there some kind of command I can add to the beginning of the routine to suspend any layout, and then another command to resume at the end of the routine?
There are two ways:
1) Put your all code (you mentioned above) in onCreate() method and at last call t1.setVisible(true);
2) Put your code in the method in which you are creating your UI (like initUI() or something like that) and call this method before setting visibility to true.
Have you considered using XML to set the text style instead of doing it programmaticly. See this Android Dve Guide page for more on this topic.
Another (bad?) way might be to use XML to set the views visibility to false and when you have made your style changes, call t1.setVisibility(true). Haven't tried this one, so it might produce a similar, unwanted result.
i have a row of buttins created like this
i want to change the background colour at runtime in code.
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
LinearLayout track1 = (LinearLayout)findViewById(R.id.my_toggle_container);
for (int i = 0; i<32; i++) {
ToggleButton tgl = new ToggleButton(this);
tgl.setId(i);
...
track1.addView(tgl);
this names the id of the togglebuttons 1, 2, 3... (i presume?)
i have an int variable called 'xBtn' that changes 1, 2,..
this is how i get a reference to the button using xBtn
String buttonID = ""+xBtn;
int resID = getResources().getIdentifier(buttonID, "id", "com.thing");
//find the button
ToggleButton tb = (ToggleButton) findViewById(resID);
//change its colour
tb.setBackgroundColor(Color.BLUE);
it crashes on the setBackgroundColor line.
it may be obvious to someone whats wrong and thats what im hoping
any help would be totaly ace ta
thanks
main.xml
<LinearLayout android:layout_width="wrap_content" android:layout_height="match_parent" android:id="#+id/my_toggle_container" android:orientation="vertical">
The id of your togglebuttons is gonna be a number from 1 to 32... However, trying to find the toggle button by id will return null because simply instantiating a new toggle button and giving an id wont help you. findViewById looks in the parent view for a child view with the specified id. If you havent added that toggle button with that id to the view, then findViewById will return null. I am 99.99% sure even without looking at the log, that it crashes because you are calling setBackgroundColor on a null object.
In other words, the id that you set a view to is only relevant once the view is actually added to a parent view. In your case you are probably trying to add these toggle buttons to your main content view, in which case you need grab hold of that view that you used for setContentView and call addView on that view and pass in each new toggle button. Note that this will probably not look right unless you also specify layoutparams for the togglebuttons.
EDIT
If thats your entire main.xml, then you've got other issues. Post the full xml file. In any event, you still are going to have to do what I've said, which is to grab hold of the view or a child view of that view and then add the toggle buttons to it via addView (after giving the togglebuttons their proper ids). Once the button has been added, then you can find it. Note though that if you're gonna add the toggle buttons to a child view of your main view, then you'll likely have to grab hold of that child view and call findViewById on THAT.
For example, you can do a nested call like this. findViewById(1) <--- gets you the LinearLayout or whatever inside of your main content view, then once you have that you can call addView on it. So LinearLayout ll = (LinearLayout)findViewById(someNumber); ll.addView(tb);
Try to use the method setTag() , and then you can get all your ToggleButton by using : findViewByTag();
Perhaps tb is null? Could you check that out?
To expand on what LuxuryMode said... What gets an ID INTO your java is inflating it via setContentView and setting it as content. That's why it's ok to have overlapping (duplicate) IDs in different layouts. You can have #+id/submit_button in layout1.xml and in layout2.xml and the Activity will get you the object via findViewById(R.id.submit_button) based on which one you have loaded into setContentView() at any given moment.
So, we're all guessing that you're probably not setting the content view and hoping that the code will find your object in your non inflated XML, which it won't. Which would lead (as everyone has guessed) to you now dealing with a null object, which you obviously can't set a background color on.
I know it gets confusing cause you have the XML RIGHT THERE!!! But the reality is that the xml isn't "alive". It's just stuff for you to look at until you have tasked the Application with inflating it and converting all of it into Android objects of some kind. A lot of the time this is done mostly transparently to you, so, it's easy to forget that none of these things really exist.
It's very likely that tb is null, because findViewById() didn't go as you expected.
You can verify this by surrounding the erroneous line with try.. catch block:
try {
tb.setBackgroundColor(Color.BLUE);
} catch (Exception e){
}
and watch for the message of e. It's likely to be null pointer exception.
In fact, I think you should not use getResources().getIdentifier(buttonID, "id", "com.thing") in the first place. It seems to me that all these resources are continuously numbered in R file, thus you should simply get the first id (as an integer), and then increment on that.
That is, you should do things like:
// The following code is not tested; I just wrote it here on SO.
for (int resID = R.id.button1; resID <= 32; resID++) {
ToggleButton tb = (ToggleButton) findViewById(resID);
tb.setBackgroundColor(Color.BLUE);
}
this should make all 32 buttons blue.
I'm new to Android and find it brutal (there seems to be an near infinite number of details and dependencies to remember).
Anywho, I got the TextSwitcher1 example app working, which uses ViewSwitcher. I'm assuming ViewSwitcher is the way to go, need to either display a map or a table, user can pick, and switch back and forth.
So I created my MapActivity in another application, seems to work. Next integrate into main app. So, call
View v = findViewById(R.layout.mapview);
and then
mSwitcher.addView(v);
except "v" is null. Why? Do I create the activity? But I don't want to show it yet. Is there such a call as "create activity but hide it until needed"? Or am I barking up the wrong tree?
Thanks for any insight.
The findViewById function returns a View based on an ID resource (R.id.something) for whatever view you have loaded in your activity (using setContentView(R.layout.main)). In your sample code, you're using a layout resource (R.layout.mapview). You should inflate the XML file, which will return a View that you can use to add to the ViewSwitcher.
Example Code:
LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View v = vi.inflate(R.layout.mapview, null);
mSwitcher.addView(v);
However, you should be able to define everything in your XML file and not have to manually add the pages to your ViewSwitcher. Here's some example code on how to do that: http://inphamousdevelopment.wordpress.com/2010/10/11/using-a-viewswitcher-in-your-android-xml-layouts/