Develop Reference

Placing Multiple Buttons to a Relative Layout without a Grid in Android

I want to add multiple buttons to a layout programmatically.
However, count of buttons is different every time and I just want them to placed next to each other with a wrap content width. After a line is filled, it should go to next line and continue that way.
What is the cleanest way to achieve that?
Thanks.

LinearLayout verticalLayout = new LinearLayout(context);
verticalLayout.setOrientation(LinearLayout.VERTICAL);
while(isActive) {
LinearLayout horziontalLayout = new LinearLayout(context);
horziontalLayout.setOrientation(LinearLayout.HORIZONTAL);
add buttons here..
//Example Button button = new Button(context);
//horziontalLayout.addView(button);
verticalLayout.addView(horziontalLayout);
isActive = false // when youe done filling up buttons..
}

easiest way should be having a vertical LinearLayout in wich you add multiple horizontal LinearLayout
//vertical one
LinearLayout vlinear = new LinearLayout(this);
vlinear.setOrientation(LinearLayout.VERTICAL);
LayoutParams vlinearParams = new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT);
vlinear.setLayoutParams(vlinearParams);
parentgroup.addView(vlinear);
//horizontal lines
for (int i=0;i<numlines){
LinearLayout hlinear = new LinearLayout(this);
hlinear.setOrientation(LinearLayout.HORIZONTAL);
LayoutParams vlinearParams = new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT);
hlinear.setLayoutParams(hlinearParams);
vlinear.addView(hlinear);
///add the loop for adding cells
for...
hlinear.addView(cell);
}

Defining a Linear Layout progmatically

I am trying to dynamically create a linear layout with a dynamic number of buttons based on certain parameters. So far I have some code that compiles but when it runs it does not display anything.
public void displayMenu()
{
LinearLayout lin = new LinearLayout(CategoryMenu.this);
lin.setOrientation(LinearLayout.VERTICAL);
lin.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
ArrayList<Button> btnList= new ArrayList<Button>();
//Test Button
Button btn1= new Button(this);
btn1.setText("Dylan");
lin.addView(btn1);
for (int i =0 ; i < 5; i++){
btnList.add(new Button(this));
btnList.get(i).setText("Hello:"+i);
lin.addView(btnList.get(i));
Log.i("CategoryMenu","Adding btn to view");
}
}
What am i doing incorrectly? I'm sure that i'm missing some thing silly here.

you have to add lin to the current hierarchy of view, or creating a new one calling setContentView(lin);

It seems that you're not adding that linear layout to a viewgroup parent.
After all your code you should add something like
myParentViewGroup.add(lin);

Before lin.addView(btn1);
You should define layoutparams for Button like:
// Defining the layout parameters of the Button
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.FILL_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
// Setting the parameters on the Button
tv.setLayoutParams(lp);

You have to add lin too the layout.
At present you have just created a Linearlayout, but you have not attached it to any layout.

LinearLayout lin = new LinearLayout(CategoryMenu.this);
lin.setOrientation(LinearLayout.VERTICAL);
lin.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
ArrayList<Button> btnList= new ArrayList<Button>();

LinearLayout Horizontal inside LinearLayout Vertical

I am trying to put a linearlayout vertical inside the linear layout programmatically, but it seems that its not working, the buttons doesnt appear, but the text view appear...
Here is my code:
(this is for a dialog..)
LinearLayout titleLayout = new LinearLayout(m_context);
titleLayout.setOrientation(LinearLayout.VERTICAL);
m_titleView = new TextView(m_context);
m_titleView.setText(title);
LinearLayout horizontalLayout = new LinearLayout(m_context);
titleLayout.setOrientation(LinearLayout.HORIZONTAL);
Button backward = new Button(m_context);
backward.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
backward.setText("Backwards");
Button newDirButton = new Button(m_context);
newDirButton.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
newDirButton.setText("New folder");
horizontalLayout.addView(backward);
horizontalLayout.addView(newDirButton);
titleLayout.addView(m_titleView);
titleLayout.addView(horizontalLayout);
Thanks in advance!

Try setting LayoutParams on horizontalLayout.
Anyway, I'd suggest moving to xml world, as this code is not maintainable.
Edit:
Answer found by the author:
titleLayout.setOrientation(LinearLayout.HORIZONTAL);
should be:
horizontalLayout.setOrientation(LinearLayout.HORIZONTAL);

Android: how to center a button programatically created?

I need to create a button programatically and have it centered on the layout, both horizontally and vertically. I am trying with the following code:
LinearLayout ll = (LinearLayout)findViewById(R.id.layoutItem);
Button b = new Button(this);
b.setBackgroundDrawable(getResources().getDrawable(R.drawable.button));
b.setLayoutParams(new LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONTENT));
b.setGravity(Gravity.CENTER_HORIZONTAL|Gravity.CENTER_VERTICAL);
ll.addView(b);
But it's not working. The button comes out on top all to the left.
Any clues on how to fix this?

I would do something like:
LinearLayout.LayoutParams ll = (LinearLayout.LayoutParams)b.getLayoutParams();
ll.gravity = Gravity.CENTER;
b.setLayoutParams(ll);
see if that works.

Or you can use a RelativeLayout as your parent View and do the following:
this.testButton= (Button) this.findViewById(R.id.testButton);
RelativeLayout.LayoutParams testLP = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
testLP.addRule(RelativeLayout.CENTER_IN_PARENT);
this.testButton.setLayoutParams(testLP);
You can set several rules for the RelativeLayout.

How to create Scrollview programmatically?

I have one table "TABLE_SUBJECT" which contain a number of subjects. I need to create
one horizontal scroll view with Subject.
How do I create a ScrollView with database items programmatically? If I enter 1o subject then it will be appear in scroll view as a button. Is it possible?

you may create it as below:
ScrollView scroll = new ScrollView(context);
scroll.setBackgroundColor(android.R.color.transparent);
scroll.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.FILL_PARENT));
scroll.addView(yourTableView);

if you have many elements first you need to wrap-up and add in the Scroll view; for example i need a many text view inside of scrollview, so you need to create ScrollView->LinearLayout->Many textview
ScrollView scrollView = new ScrollView(context);
scrollView.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
TextView textView = new TextView(context);
textView.setText("my text");
LinearLayout linearLayout = new LinearLayout(context);
linearLayout.setOrientation(LinearLayout.VERTICAL);
linearLayout.setGravity(Gravity.RIGHT);
linearLayout.addView(textView);
scrollView.addView(linearLayout);

this may help you.
HorizontalScrollView hsrll = (HorizontalScrollView)findViewById(R.id.hrsll);
b = new Button(this);
for (int i = 0; i < 5; i++) {
b.setWidth(LayoutParams.WRAP_CONTENT);
b.setHeight(LayoutParams.WRAP_CONTENT);
b.setText("b"+i);
b.setId(100+i);
hsrll.addView(b);
}
instead of for loop just modify the code as your need(no of records in db). but this the code for creating buttons in dynamically.

I was doing it like this:
Create xml with LinearLayout inside the ScrollView
Create xml as item in ScrollView
In activity set main content as xml with ScrollView
Loop through all table elements with adding new View to LinearLayout form main view
For me works fine.

In Kotlin you can use the below code
val scroll = ScrollView(context)
scroll.setBackgroundColor(R.color.transparent)
scroll.layoutParams = LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.FILL_PARENT
)
scroll.addView(yourTableView)