Develop Reference

Add UI elements dynamically in android

I want to add some ui elements to my android app, a Button for example!
But I can't find a complete tutorial! I found this code after a lot of searches:
LinearLayout ll = (LinearLayout)findViewById(R.id.layout);
Button btn = new Button(this);
btn.setText("Manual Add");
btn.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
ll.addView(btn);
My first problem is first line! Can you explain it for me please? What is R.id.layout? I know R is an object for resources but I don't know what is layout!
Second problem is line 3, What is LayoutParams?
Thank you all!

You can create views using default constructors for example
Button button = new Button(context);
After that you should determine to which type of parent view you are going to attach it, and create corresponding layot params. Every parent view LayoutParams type has uniqe customize methods, for example rules of RelativeLayout.LayoutParams.
FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(width, height)
//customize params here
button.setLayoutParams(params)
Attach view to your parent view
frameLayout.addView(button)
That is it.

LinearLayout ll = (LinearLayout)findViewById(R.id.layout);// you are getting a refrence to your layout
Button btn = new Button(this); // creating a new object of button type
btn.setText("Manual Add"); //setting the button text
btn.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,
LayoutParams.WRAP_CONTENT)); //setting the width and height of the element
ll.addView(btn);//adding the button to your layout
R.id.layout is the name of your activity layout

It is the parent view which you are going to add your views. In your example it is a LinearLayout called layout.

how to i manage textviews inside linear layout orientation horizontal

Code :
LinearLayout linearLayout2;
final JSONArray answer=jsonObject1.getJSONArray("answer");
//Here get Answer from question
((ViewGroup) findViewById(R.id.linearLayout2)).removeView(linearLayout2); //Here remove preselected radiobuttons
linearLayout2 = new LinearLayout(TestActivity2.this); //Here create new viewgroup when user click next and previous
linearLayout2.setOrientation(LinearLayout.HORIZONTAL);
linearLayout2.setGravity(Gravity.FILL_HORIZONTAL);
indexAns=new String[answer.length()];
for(int j=0;j<answer.length();j++)
{
final JSONObject jsonObject2 = answer.getJSONObject(j);
final String answer_ans=jsonObject2.getString("answer_ans"); //get answer from loop
answer_id=jsonObject2.getString("answer_id");
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
//Here create radio buttons depending on answer loop
final TextView textBtn = new TextView(TestActivity2.this);
textBtn.setId(Integer.parseInt(answer_id));
textBtn.setLayoutParams(params);
textBtn.setAllCaps(true);
textBtn.setTextSize(12);
textBtn.setPadding(5,5,5,5);
textBtn.setGravity(Gravity.LEFT | Gravity.CENTER |Gravity.RIGHT);
textBtn.setTextColor(Color.parseColor("#000000"));
indexAns[j]=answer_id;

You may want to post your layout xml files. Looks like you are manipulating the layout programatically, which, in most cases in unnecessary. You can accomplish the same goal via xml layout files.
Also, you can save a lot of time using styles for formatting.
Check out the following layout documentation
https://developer.android.com/guide/topics/ui/declaring-layout.html
Check out the TextView documentation:
https://developer.android.com/reference/android/widget/TextView.html

Android: Align a Button to the Right in LinearLayout

I have a piece of code which I use to create a new LinearLayout. Within the layout I wish to add a TextView which contains both a label and a value. Then next to it on the right I want to display the button. I want the button to be located toward the end of the screen, without stretching the button. I am happy with the button width and height as WARP_CONTENT.
How can I achieve this in code? I have barely any XML so using XML is not an option. I am trying to make the app as dynamic as possible, so I decided to steer clear of XML.
Please see the code below:
// Build a button
final Button addButton = new Button(task.getParent());
addButton.setText("Add New");
addButton.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
// Open a file picker here to let the user pick a file
}
});
// Build a new layout to hold all the elements
LinearLayout verticalLayout = new LinearLayout(task.getParent());
verticalLayout.setOrientation(LinearLayout.HORIZONTAL);
verticalLayout.addView(sizeTextView);
verticalLayout.addView(addButton);
Thank you guys in advance.

Try this: Add Space (View) between TextView & Button.
// View space = new View(parent_context);
View space = new View(task.getParent());
// Width:0dp, Height:1 & Weight: 1.0
LinearLayout.LayoutParams spaceLP = new LinearLayout.LayoutParams(0, 1, 1.0f);
space.setLayoutParams(spaceLP);
verticalLayout.addView(sizeTextView);
verticalLayout.addView(space);
verticalLayout.addView(addButton);

Add textview with size and gravity,like this:
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONTENT);
params.setLayoutDirection(Gravity.RIGHT|Gravity.CENTER_VERTICAL);
verticalLayout.addView(sizeTextView,params);

To achieve this you should use Relative layout and RelativeLayout.LayoutParams. By using LayoutParams you can set the rule to align your views as per your requirements.
for example
RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams)button.getLayoutParams();
params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
params.addRule(RelativeLayout.LEFT_OF, R.id.id_to_be_left_of);
button.setLayoutParams(params);

Adding Views to LinearLayout with weight programmatically

I am getting stucked on the following problem:
For a questions app I want to implement a nice output for a survey showing the possible answers and the percentage of people answered the specific question. Therefore, I want to add a "bar" to my app that displays the percentage. I try to solve this by using views and weighting them in a linear layout.
I want to add the different answers programmatically, this is the code I've got so far.
My problems are, that I am not getting closer to weighting the views and resizing them.
/* Add all questions */
RelativeLayout my_root = (RelativeLayout) findViewById(R.id.ownerRL);
/* Add a new Linearlayout as a container for the question */
LinearLayout A = new LinearLayout(this);
A.setOrientation(LinearLayout.HORIZONTAL);
my_root.addView(A);
/* Create a new View in this container, for the status bar */
View new_view = new View(getBaseContext());
new_view.setBackgroundColor(Color.YELLOW);
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(50, 20, 3);
RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) A.getLayoutParams();
params.addRule(RelativeLayout.BELOW, R.id.question1);
A.addView(new_view);
View new_view2 = new View(getBaseContext());
new_view.setBackgroundColor(Color.GREEN);
ViewGroup.LayoutParams lp2 = new ViewGroup.LayoutParams(50, 20);
RelativeLayout.LayoutParams params2 = (RelativeLayout.LayoutParams) A.getLayoutParams();
params2.addRule(RelativeLayout.BELOW, R.id.question1);
params2.addRule(RelativeLayout.LEFT_OF, new_view.getId());
A.addView(new_view2);
The Green view should actually be right of the yellow one (which is not visible).
How do get it managed such that it creates a red/white bar that has a height of 4px and the red and weight parts are weighted?
Thanks for your help!

check this link, Set Linear Layout weight it like this
LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT, 1.0f);
The last parameter is weight.Hope this help.

Adding margins to button object programatically

Need to set left margin to a button object programatically.
This is the code segment:
RelativeLayout rl = (RelativeLayout) findViewById(R.id.for_button);
MarginLayoutParams ml = new MarginLayoutParams(-2,-2);
ml.setMargins(5, 0, 0, 0);
Button btn = new Button(this);
btn.setText("7");
btn.setTextColor(Color.WHITE);
btn.setBackgroundResource(R.drawable.date_button);
rl.addView(btn,ml)
I also tried
btn.setLayoutParams(ml);
rl.addView(btn);
Whats the big problem. Or is there any alternative way?

Alright, I'm gonna give this a shot IronBlossom; this is how I do it and I hope it works:
LinearLayout myLinearLayout = (LinearLayout)findViewById(R.id.my_linear_layout);
Button myButton = new Button(this);
// more myButton attribute setting here like text etc //
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
params.setMargins(5,0,0,0);
myLinearLayout.addView(myButton, params);
best,
-serkan

You use a RelativeLayout as the parent for the button, but you don't specify any rules for the it where to place the button (e.g. ALIGN_PARENT_LEFT and ALIGN_PARENT_TOP).
You have to set rules for position when using a RelativeLayout though, so this messes with the layout calculation. This means that you have to use RelativeLayout.LayoutParams instead of the MarginLayoutParams because the former allows these rules and has proper default values set.
Alter this line:
MarginLayoutParams ml = new MarginLayoutParams(-2,-2);
to
RelativeLayout.LayoutParams ml = new RelativeLayout.LayoutParams(-2,-2);
Chances are that you also want to add rules because the default positioning values don't suit you (views get positioned in the top left corner of the parent layout by default). You can use RelativeLayout.LayoutParams.addRule() for that.