I am still pretty new to Android development, and I have not been able to find any examples of how to do this.
In my Activity, I use "setContextView(new myViewClass)" to designate a View-extended class as the one to load. Everything works fine in terms of loading the view, where I create various elements (LinearLayouts, buttons, etc.) based on a number of conditions. Unfortunately, I cannot get any of these elements to actually appear on the screen.
I guess my question goes to a greater understanding of Views. All of the examples I've seen concern setting an xml file as the base view and then altering it within the code. Is there some alternative to this?
Thanks.
Here is an example code I've been trying to make work. There are other things going on, but this is the relevant info. For program context, this class is substantiated with the setContextView(new createView(this)):
public createView(Context c){
super(c);
// Create a simple layout
LinearLayout layout = new LinearLayout(top.getContext());
layout.setOrientation(LinearLayout.VERTICAL);
// Create test text
TextView mTestText = new TextView(c);
mTestText.setText("This is a test");
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.FILL_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
lp.setMargins(10, 10, 10, 10);
layout.addView(mTestText, lp);
}
I think the problem is that you are not adding the layout to your CreateView. However, the View class does not have an add method (see http://developer.android.com/reference/android/view/View.html).
Since LinearLayout is the base view for your extended view, you could extend LinearLayout instead and add the TextView to your extended class. If you do this, your CreateView class would probably look something like this:
/**
* Since the LinearLayout is the base layout, we'll extend it.
*/
public class CreateView extends LinearLayout {
public CreateView(Context context) {
super(context);
setOrientation(LinearLayout.VERTICAL);
TextView mTestText = new TextView(context);
mTestText.setText("This is a test");
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.FILL_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
lp.setMargins(10, 10, 10, 10);
addView(mTestText, lp);
}
}
Related
The app I am trying to make, has got a lot of similar LinearLayouts and textViews that need to be created programmatically and placed on the screen in a specific order.
So I decided to define a method which returns one element, and for the furthur uses,I will put the method in some loop to produce the others. but when I create a view or layout this way, nothing shows up or sometimes the app crashes, as if it's been sent null to addView(). It only works when I create the View/Layout in onCreate() and then I use it right there afterwards.So , any ideas that I can use the method to creat my Layout/View? Because they are too many and it's not possible to create them one by one in onCreate()
Here's the method:
public LinearLayout createLinearLayout(){
TextView tv_day = new TextView(this);
tv_day.setWidth(LinearLayout.LayoutParams.MATCH_PARENT);
tv_day.setHeight(LinearLayout.LayoutParams.WRAP_CONTENT);
tv_day.setGravity(Gravity.END);
tv_day.setText("27");
LinearLayout ll_horizontal = new LinearLayout(getBaseContext());
LinearLayout.LayoutParams ll_horizontal_params = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.MATCH_PARENT);
ll_horizontal.setLayoutParams(ll_horizontal_params);
ll_horizontal.setOrientation(LinearLayout.HORIZONTAL);
ll_horizontal.addView(tv_day);
return ll_horizontal;
}
and this is onCreate() which doesn't add any linear layouts with a textView in it :
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_month_view);
LinearLayout ll= createLinearLayout();
LinearLayout mainLayout = (LinearLayout) findViewById(R.id.activity_month_view);
mainLayout.addView(ll);
}
I think this should help
- add an empty linear layout in XML with some id.
- reference that layout in code
- add elements to that layout dynamically
Hey was just checking your code. Its working perfectly now just try this method.
public LinearLayout createLinearLayout(){
TextView tv_day = new TextView(this);
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
tv_day.setLayoutParams(layoutParams);
tv_day.setGravity(Gravity.CENTER);
tv_day.setText("27");
LinearLayout ll_horizontal = new LinearLayout(getBaseContext());
LinearLayout.LayoutParams ll_horizontal_params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.MATCH_PARENT);
ll_horizontal.setLayoutParams(ll_horizontal_params);
ll_horizontal.setOrientation(LinearLayout.HORIZONTAL);
ll_horizontal.addView(tv_day);
return ll_horizontal;
}
You know this JoystickView from http://code.google.com/p/mobile-anarchy-widgets/wiki/JoystickView ?
Well, I tried to implement it. No Problems with it. I couldn't change It's size because I Added It programmatically. I somehow found out how to change the size, but now It's stuck in the upper left corner and everything I found for three hours got me a NullPointerException on the LayoutParams param I've created or was rejected because It wasn't castable or something to begin with.
public class GameActivity extends Activity implements JoystickMovedListener{
private GraphicsHolder mGraphicsHolder;
private String TAG = "GameActivity";
/*
* creates a new GraphicsHolder and sets it its ContentView
* the GraphicsThread is being included in the GraphicsHolder
*/
#Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
Log.d(TAG, "created");
FrameLayout gameScreen = new FrameLayout(this);
mGraphicsHolder = new GraphicsHolder(this);
JoystickView Joystick = new JoystickView(this);
// I need to set the Gravity HERE
Joystick.setLayoutParams(new RelativeLayout.MarginLayoutParams(500,500));
gameScreen.addView(mGraphicsHolder);
gameScreen.addView(Joystick);
setContentView(gameScreen);
}
}
Now Here's my Question: can you somehow set the Gravity of this View programmatically?
You can try this
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(500,500);
params.addRule(RelativeLayout.CENTER_IN_PARENT, RelativeLayout.TRUE);
Joystick.setLayoutParams(params);
Try to set gravity center to FrameLayout and use ViewGroup.LayoutParams set Joystick LayoutParams :
FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT,FrameLayout.LayoutParams.MATCH_PARENT);
params.gravity = Gravity.CENTER;
gameScreen.setLayoutParams(params);
Joystick.setLayoutParams(new ViewGroup.LayoutParams(500,500));
try this.
FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) Joystick.getLayoutParams();
params.gravity = Gravity.TOP;// desired gravity
Joystick.setLayoutParams(params);
dont change ur code just add this after setContentView(gameScreen); hope it works
Well, I found the answer, but it's a completely different approach, since none of the above or those I found elsewhere worked for me.
I did the following changes in the onCreate method:
mGraphicsHolder = new GraphicsHolder(this);
LayoutInflater inflate = (LayoutInflater)
getSystemService(Context.LAYOUT_INFLATER_SERVICE);
setContentView(mGraphicsHolder);
getWindow().addContentView(inflate.inflate(
R.layout.controllayout, null), new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.FILL_PARENT));
Joystick = (JoystickView) getWindow().findViewById(R.id.joystickView1);
Joystick.setOnJostickMovedListener(this);
Now I got my Joystick on an XML Layout, but It actually works (at least in my case where nothing else worked), and it's quite easy to make changes in things of Layout etc.
I created a custom view. In it, theres a line, a textview, another line. beneath the bottom line, i wanted to put a new horizontally oriented linearlayout. when i run it, this nested linearlayout doesnt seem to show up at all. Instead, i can see the test button right underneath the bottom line. what am i doing wrong?
public class MyView extends LinearLayout {
public MyView(Context context, Question question) {
super(context);
// this.setLayoutParams(params);
this.setOrientation(VERTICAL);
this.setBackgroundColor(Color.WHITE);
LinearLayout.LayoutParams lineParams = new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT, 2);
View topLine = new View(context);
lineParams.setMargins(0, 15, 0, 0);
topLine.setBackgroundColor(Color.argb(255, 0, 159, 218));
topLine.setLayoutParams(lineParams);
this.addView(topLine);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
//Challenge Question
TextView questionText = new TextView(context);
questionText.setTextColor(Color.BLACK);
questionText.setTextSize(14);
questionText.setLayoutParams(params);
questionText.setGravity(Gravity.CENTER_HORIZONTAL);
questionText.setText(question.getQuestion());
this.addView(questionText);
View bottomLine = new View(context);
bottomLine.setBackgroundColor(Color.argb(255, 0, 159, 218));
bottomLine.setLayoutParams(lineParams);
this.addView(bottomLine);
LinearLayout innerLayout = new LinearLayout(context);
LinearLayout.LayoutParams innerLayoutParams = new LinearLayout.LayoutParams(300, LayoutParams.WRAP_CONTENT);
innerLayout.setLayoutParams(innerLayoutParams);
innerLayout.setBackgroundColor(Color.RED);
innerLayout.setOrientation(HORIZONTAL);
//TableLayout for the multiple choices
TableLayout tableLayout = new TableLayout(context);
LayoutParams tableLayoutParams = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
// tableLayoutParams.weight = .8f;
tableLayout.setBackgroundColor(Color.RED);
tableLayout.setLayoutParams(tableLayoutParams);
innerLayout.addView(tableLayout);
this.addView(innerLayout);
Button button = new Button(context);
button.setLayoutParams(params);
button.setText("testing 123");
this.addView(button);
}
Note that I pasted the code without all the stuff that I added to the tablelayout. I probably should have pasted that too. But it didn't work when I did that either. but either way, if i set the nested linearlayout to 300 width and set a background color of red to it, i should at least see it, no?
Think about what the height of the inner layout should be. Right now it is wrap_content and contains a TableLayout (with no rows) with its height also set to wrap_content. There doesn't seem to be anything in that inner layout giving it a height dimension, so that may be why it is not being displayed.
Trying the following will make your layout visible:
LinearLayout.LayoutParams innerLayoutParams = new LinearLayout.LayoutParams(300, 300);
More usefully, you can try adding something with a real width/height to the TableLayout.
Also consider writing your layout in XML to better separate your application logic and the presentation.
I'm trying to create a View dynamically (on click). Any person have any idea why this does not work. It just opens a blank (BLACK) screen. When i click back it moves to previous screen as well. And i need to know the way i'm trying to set the team is correct.
public class Details extends Activity {
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
//setTheme(android.R.style.Theme_Dialog);
TextView label = new TextView(this);
label.setText("Hello This text");
label.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
label.setTextSize(20);
label.setGravity(Gravity.CENTER);
TableRow tr = new TableRow(this);
tr.addView(label);
TableLayout tl = new TableLayout(this);
tl.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
tl.setGravity(Gravity.CENTER);
tl.addView(tr);
ScrollView sv = new ScrollView(this);
sv.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
sv.addView(tl);
setContentView(sv);
}
}
There is an msg in LogCat as following
couldn't save which view has focus because the focused view ##### has no id
Well one obvious thing is that you are using generic LayoutParams, not the correct parameters for the layout manager. For example you are not using a TableLayout.LayoutParams for the TextView so you are not actually telling it how to layout the text view within the table structure.
I also suggest using hierarchyviewer to look at what is going on with your view hierarchy.
Is the activity declared in the Manifest.xml?
You must to put
#Override
I had the similar problem
I want to create a relative Layout dynamically through code with 2 Textviews one below the other.How to implement android:layout_below property through code in Android.
can anyone help me in sorting out this issue.
Thanks in Advance,
final TextView upperTxt = (...)
upperTxt.setId(12345);
final TextView lowerTxt = (...);
final RelativeLayout.LayoutParams params = RelativeLayout.LayoutParams(this, null);
params.addRule(RelativeLayout.BELOW, 12345);
lowerTxt.setLayoutParams(params);
Here is my solution for my special Problem.
In case the username wouldn't be found in the db i had to create a RelativeLayout that looks like the xml-generated one.
// text view appears on top of the edit text
enterNameRequest = new TextView(mainActivity.getApplicationContext());
// fill the view with a string from strings.xml
enterNameRequest.setText(mainActivity.getResources().getString(R.string.enterNameRequest));
// edit text appears below text view and above button
enterName = new EditText(mainActivity.getApplicationContext());
enterName.setId(667);
// button appears at the bottom of the relative layout
saveUserName = new Button(mainActivity.getApplicationContext());
saveUserName.setText(mainActivity.getResources().getString(R.string.useUserName));
saveUserName.setId(666);
// generate the relative layout
RelativeLayout layout = new RelativeLayout(mainActivity.getApplicationContext());
layout.setId(668);
// set a background graphic by its id
layout.setBackgroundDrawable(mainActivity.getApplicationContext().getResources().getDrawable(R.drawable.background_head_neutral));
// runtime told me that i MUST use width and height parameters!
LayoutParams params2 = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
params2.addRule(RelativeLayout.ABOVE, 666);
enterName.setLayoutParams(params2);
LayoutParams params3 = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
params3.addRule(RelativeLayout.ABOVE, 667);
enterNameRequest.setLayoutParams(params3);
LayoutParams params4 = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
params4.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM, 668);
saveUserName.setLayoutParams(params4);
// add views
layout.addView(enterNameRequest);
layout.addView(enterName);
layout.addView(saveUserName);
/* todo: set button action */
mainActivity.setContentView(layout);
What i found out additionally:
It is not so good to manipulate the layout manually from within java!
You should better use a new Activity and set a new layout in it.
This way, the application-code is readable a lot better!
I even tried to set several layouts (not manually, but wit setContentView) in one activity, and it turned out that i didn't know where what was accessing what else... Also, i had a great problem in adding onClickListeners... so you better use -- android:onClick="myButtonMethod" -- in your button tag in the xml and have a method in your according activity, which uses the layout, like this:
public void myButtonMethod(View v){
// do stuff
}
This improves performance because you are not using additional Listeners - but you use the already available Listener that is bound to your activity in every case.
u can try this
LinearLayout.LayoutParams leftMarginParams = new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);``
leftMarginParams.leftMargin = 50;
Button btn1 = new Button(this);
btn1.setText("Button1");
linLayout.addView(btn1, leftMarginParams)