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 have a question regarding Android Activitys:
An Activity has the Method addContentView(View) while a ViewGroup has a (similar?) addView(View) Method.
Unfortunately its undocumented where the View from addContentView is placed. Is it like a LinearLayout just adding the View to the bottom, or is it more like a FrameLayout, which adds its Views "onTop" ? Does it depend on the ViewGroup set by setContentView?
If I dive into the sources I see that addContentView will call Window's abstract Method addContentView. Unfortunately I cannot see which class is implementing this Method. So whats the behaviour of Activitys addContentView exactly?
The base layout of every activity is a FrameLayout. This means the layout you usually set via setContentView() is a child of this layout. addContentView() adds just another child, therefore it behaves like a FrameLayout (which means it adds new UI elements above existing ones).
You can check this by using a tool called hierachyviewer from your ANDROID_SDK\tools folder. Here are two screenshots:
This is the layout before calling addContentView(), my activity consists of the default FrameLayout, holding a LinearLayout with a Button (my layout here). This is reflected in the bottom row here, the other elements above are the title/statusbar.
After adding a TextView via addContentView() it looks like this. You can see that the base FrameLayout got a new child.
public void addContentView(View view,
LayoutParams params) {
mActivity.addContentView(view, params);
}
//
public static void SetActivityRoot(Activity c) {
View v = ((ViewGroup)c.findViewById(android.R.id.content)).getChildAt(0);
ScrollView sv = new ScrollView(c);
LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT,
LayoutParams.MATCH_PARENT);
sv.setLayoutParams(lp);
((ViewGroup) v.getParent()).removeAllViews();
sv.addView((View) v);
c.addContentView(sv, lp);
}
//
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LinearLayout mainLayout =
(LinearLayout)findViewById(R.id.mainlayout);
//newButton added to the existing layout
Button newButton = new Button(this);
newButton.setText("Hello");
mainLayout.addView(newButton);
//anotherLayout and anotherButton added
//using addContentView()
LinearLayout anotherLayout = new LinearLayout(this);
LinearLayout.LayoutParams linearLayoutParams =
new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
Button anotherButton = new Button(this);
anotherButton.setText("I'm another button");
anotherLayout.addView(anotherButton);
addContentView(anotherLayout, linearLayoutParams);
}
}
My question is simple,
How to set my buttons layout_gravity programmatically?
I found this on internet, but it simply throws me a Nullpointer exception:
Button MyButton = new Button(this);
LinearLayout.LayoutParams lllp=(LinearLayout.LayoutParams)MyButton.getLayoutParams();
lllp.gravity=Gravity.RIGHT;
MyButton.setLayoutParams(lllp);
MyLinearLayout.addView(MyButton);
Any solution?
Java
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);
params.weight = 1.0f;
params.gravity = Gravity.TOP;
button.setLayoutParams(params);
Kotlin
val params = LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT
).apply {
weight = 1.0f
gravity = Gravity.TOP
}
For gravity values and how to set gravity check Gravity.
Basically, you should choose the LayoutParams depending on the parent. It can be RelativeLayout, LinearLayout etc...
I'd hate to be resurrecting old threads but this is a problem that is not answered correctly and moreover I've ran into this problem myself.
Here's the long bit, if you're only interested in the answer please scroll all the way down to the code:
android:gravity and android:layout_gravity works differently. Here's an article I've read that helped me.
GIST of article: gravity affects view after height/width is assigned. So gravity centre will not affect a view that is done FILL_PARENT (think of it as auto margin). layout_gravity centre WILL affect view that is FILL_PARENT (think of it as auto pad).
Basically, android:layout_gravity CANNOT be access programmatically, only android:gravity.
In the OP's case and my case, the accepted answer does not place the button vertically centre.
To improve on Karthi's answer:
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.gravity = Gravity.CENTER;
button.setLayoutParams(params);
Link to LinearLayout.LayoutParams.
android:layout_gravity shows "No related methods" meaning cannot be access programatically.
Whereas gravity is a field in the class.
I had a similar problem with programmatically setting layout_gravity on buttons in a GridLayout.
The trick was to set gravity on the button layoutParams AFTER the button was added to a parent (GridLayout), otherwise the gravity would be ignored.
grid.addView(button)
((GridLayout.LayoutParams)button.getLayoutParams()).setGravity(int)
MyButton.setGravity(Gravity.RIGHT);
For layout_gravity use the answer stated by "karthi". This method sets gravity to place the children inside the view.
layoutParams2.gravity = Gravity.RIGHT|Gravity.BOTTOM;
use this to add mor than one gravity
If you want to change the layou_gravity of an existing view do this:
((FrameLayout.LayoutParams) view.getLayoutParams()).gravity = Gravity.BOTTOM;
Remember to use the right LayoutParams based on the Layout type your view is in. Ex:
LinearLayout.LayoutParams
KOTLIN setting more than one gravity on FrameLayout without changing size:
// assign more than one gravity,Using the operator "or"
var gravity = Gravity.RIGHT or Gravity.CENTER_VERTICAL
// update gravity
(pagerContainer.layoutParams as FrameLayout.LayoutParams).gravity = gravity
// refresh layout
pagerContainer.requestLayout()
This question is old but I just had the same problem and solved it like this
LayoutParams lay = new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT)
lay.gravity = Gravity.CENTER;
I use someting like that: (Xamarin and C# code)
LinearLayout linLayout= new LinearLayout(this);
linLayout.SetGravity(GravityFlags.Center);
TextView txtView= new TextView(this);
linLayout.AddView(txtView);
the SetGravity puts my textView in the center of the layout.
So SetGravity layout property refer to layout content
In case you need to set Gravity for a View use the following
Button b=new Button(Context);
b.setGravity(Gravity.CENTER);
For setting layout_gravity for the Button
use gravity field for the layoutparams as
LayoutParams lp=new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
lp.gravity=Gravity.CENTER;
try this
hope this clears
thanks
If you want to put a view in the center of parent, you can do with following code..
public class myLayout extends LinearLayout {
public myLayout(Context context) {
super(context);
RelativeLayout vi = (RelativeLayout) ((LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(
R.layout.activity_main, null);
LinearLayout.LayoutParams cc = new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
cc.gravity = Gravity.CENTER;
this.setGravity(Gravity.CENTER);
this.addView(vi);
}
}
these code section make LinearLayout put the first view elements in the center of parent.
So, we system don't consider the initial width and high to arrange view in the center .
I do the code section well.
The rest of the answers are right, I want to add more explaination. The layout_gravity is about how to position the view in parent view.
You must set gravity **after method parentView.addView() ** was called. We can see the code:
public void setLayoutParams(ViewGroup.LayoutParams params) {
if (params == null) {
throw new NullPointerException("Layout parameters cannot be null");
}
mLayoutParams = params;
resolveLayoutParams();
if (mParent instanceof ViewGroup) {
((ViewGroup) mParent).onSetLayoutParams(this, params);
}
requestLayout();
}
And the problem of null pointer is because it's not calling addView before getLayoutParams().
The annotation was already said "This method may return null if this View is not attached to a parent ViewGroup or {#link#setLayoutParams(android.view.ViewGroup.LayoutParams)} was not invoked successfully. When a View is attached to a parent ViewGroup, this method must not return null."
to RelativeLayout, try this code , it works for me:
yourLayoutParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
Perfectly Working!!! None of the above answer works for me. In Xml file setting gravity and setting layout_gravity is different. Check out the below code
// here messageLL is the linear layout in the xml file
// Before adding any view just remove all views
messageLL.removeAllViews();
// FrameLayout is the parent for LinearLayout
FrameLayout.LayoutParams params = new
FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
params.gravity = Gravity.CENTER|Gravity.CENTER_VERTICAL;
messageLL.setLayoutParams(params);
messageText.setVisibility(View.GONE);
messageNoText.setVisibility(View.VISIBLE);
messageLL.addView(messageNoText);
Also check This,where you can find clear explanation about gravity and layout_gravity .
Most of above answer are right, so written a helper methods, so you can use it
directly in you project .
set layout_gravity programmtically
// gravity types : Gravity.BOTTOM, Gravity.START etc.
// view : can be any view example : button, textview, linearlayout, image etc.
// for single view
public static void setLayoutGravity(int gravity, View view){
((LinearLayout.LayoutParams) view.getLayoutParams()).gravity = gravity;
}
// for mulitple views
public static void setLayoutGravity(int gravity, View ...view){
for(View item : view)
((LinearLayout.LayoutParams) item.getLayoutParams()).gravity = gravity;
}
Modify the existing layout params and set layout params again
//Get the current layout params and update the Gravity
(iv.layoutParams as FrameLayout.LayoutParams).gravity = Gravity.START
//Set layout params again (this updates the view)
iv.layoutParams = layoutParams
I switched from LinearLayout.LayoutParams to RelativeLayout.LayoutParams to finally get the result I was desiring on a custom circleview I created.
But instead of gravity you use addRule
RelativeLayout.LayoutParams mCircleParams = new RelativeLayout.LayoutParams(circleheight,circleheight);
mCircleParams.addRule(RelativeLayout.CENTER_IN_PARENT);
int width=getResources().getDisplayMetrics().widthPixels;
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams
(width, width);
params.gravity = Gravity.CENTER;
iv_main_text = new HTextView(getContext());
iv_main_text.setLayoutParams(params);
iv_main_text.setBackgroundColor(Color.BLUE);
iv_main_text.setTextSize(60);
iv_main_text.setGravity(Gravity.CENTER);
iv_main_text.setTextColor(Color.BLACK);
FloatingActionButton sendFab = new FloatingActionButton(this);
FrameLayout.LayoutParams layoutParams = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
layoutParams.setMargins(32, 32, 32, 32);
layoutParams.gravity = Gravity.END|Gravity.BOTTOM;
sendFab.setLayoutParams(layoutParams);
sendFab.setImageResource(android.R.drawable.ic_menu_send);
Try this code
Button btn = new Button(YourActivity.this);
btn.setGravity(Gravity.CENTER | Gravity.TOP);
btn.setText("some text");
or
btn.setGravity(Gravity.TOP);
I need to create a button in Java. Below is my code:
Button b = new Button(MyClass.this);
b.requestLayout();
LayoutParams lp = b.getLayoutParams();
lp.height = LayoutParams.WRAP_CONTENT;
lp.width = LayoutParams.WRAP_CONTENT;
b.setLayoutParams(lp);
b.setText("bla");
b.setTextSize(16);
b.setOnClickListener(myListener);
I then add this button to the bottom of a ListView:
getListView().addFooterView(b);
However this crashes, because getLayoutParams returns null.
Even if I create new LayoutParams instead of getLayoutParams, i.e.:
Button b = new Button(MyClass.this);
LayoutParams lp = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
b.setLayoutParams(lp);
b.setText("bla");
b.setTextSize(16);
b.setOnClickListener(myListener);
then the application crashes. Without setLayoutParams, it runs fine, but my button is not sized properly.
How can I size my button?
You have to add this button to a view if you want to get LayoutParams from button. Or just create new LayoutParams and set it.
It's returning null because when you programmatically create a widget, it has no layout params! (Until you add it to a view, then it receives defaults from the LayoutManager)
edit: above is referring to line 3 of your code
Set them like this:
TextView moneyTV = new TextView(this);
LayoutParams lp1 = new LayoutParams(HeightParamHere, WidthParamHere, WeightParamHere);
moneyTV.setLayoutParams(lp1);
Edit2: here's some readybake replacement code.
Button b = new Button(MyClass.this);
b.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
b.setText("bla");
b.setTextSize(16);
b.setOnClickListener(myListener);
Assuming you have defined myListener, this should work.
Because I'm adding this button via ListView::addFooterView, it turns out I had to use the ListView type.
b.setLayoutParams(new ListView.LayoutParams(ListView.LayoutParams.WRAP_CONTENT, ListView.LayoutParams.WRAP_CONTENT));
Using this instead of just LayoutParams resolves my crash. Hope this helps others.