Dynamic number of buttons in LinearLayout

Question

In the onCreate method of my Activity I know the number of Buttons which I want in col0. In the following example it are four Buttons. Then my TextView v0 gets the android:layout_weight set to number of buttons minus one (this is because v1 should be of the same height as all the Buttons). Instead of providing for each possible number of buttons an own xml file it would be much nicer, if one could generalize such that dynamic java codes somehow produces the appropriate layout. How is that possible?

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:baselineAligned="false"
    android:orientation="horizontal">

    <LinearLayout
        android:id="@+id/col0"
        android:layout_width="0dip"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:baselineAligned="false"
        android:orientation="vertical">

        <Button
            android:id="@+id/b0"
            style="@style/MyButton" />

        <Button
            android:id="@+id/b1"
            style="@style/MyButton" />

        <Button
            android:id="@+id/b2"
            style="@style/MyButton" />

        <Button
            android:id="@+id/b3"
            style="@style/MyButton" />

    </LinearLayout>

    <LinearLayout
        android:id="@+id/col1"
        android:layout_width="0dip"
        android:layout_height="match_parent"
        android:layout_weight="6"
        android:baselineAligned="false"
        android:orientation="vertical">

        <TextView
            android:id="@+id/v0"
            android:layout_width="match_parent"
            android:layout_height="0dip"
            android:layout_weight="3" />

        <TextView
            android:id="@+id/v1"
            android:layout_width="match_parent"
            android:layout_height="0dip"
            android:layout_weight="1" />

    </LinearLayout>

</LinearLayout>

Answer 1

First prepare all the possible ids, here 10 buttons max (put it in res/values) :

ids.xml

<?xml version="1.0" encoding="UTF-8"?>
<resources>
    <item type="id" name="b0" />
    <item type="id" name="b1" />
    <item type="id" name="b2" />
    <item type="id" name="b3" />
    <item type="id" name="b4" />
    <item type="id" name="b5" />
    <item type="id" name="b6" />
    <item type="id" name="b7" />
    <item type="id" name="b8" />
    <item type="id" name="b9" />
</resources>

If you are using API >= 17, you can avoid this file and use View.generateViewId()

If you don't need ids, skip the above part

Then, here is your main layout :

main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:baselineAligned="false"
    android:orientation="horizontal">

    <LinearLayout
        android:id="@+id/col0"
        android:layout_width="0dip"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:baselineAligned="false"
        android:orientation="vertical">    
    </LinearLayout>

    <LinearLayout
        android:id="@+id/col1"
        android:layout_width="0dip"
        android:layout_height="match_parent"
        android:layout_weight="6"
        android:baselineAligned="false"
        android:orientation="vertical">

        <TextView
            android:id="@+id/v0" />

        <TextView
            android:id="@+id/v1"
            android:layout_width="match_parent"
            android:layout_height="0dip"
            android:layout_weight="1" />

    </LinearLayout>

</LinearLayout>

Then, use the code to generate your layout :

setContentView(R.layout.main);
int buttonsNumber = 5; // Put here your number of buttons
LinearLayout col0 = (LinearLayout) findViewById(R.id.col0);

for(int i = 0; i < buttonsNumber; i++)
{
    try
    {
        Button newButton = new Button(this);
        newButton.setId(R.id.class.getField("b"+i).getInt(null));
        // Since API Level 17, you can also use View.generateViewId()
        newButton.setLayoutParams(new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, 0, 1));
        col0.addView(newButton);
    }
    catch (Exception e)
    {
        // Unknown button id !
        // We skip it
    }
}

TextView v0 = (TextView) findViewById(R.id.v0);
v0.setLayoutParams(new TableLayout.LayoutParams(LayoutParams.match_parent, 0, buttonsNumber - 1));

Answer 2

int buttonsNumber = YOUR_BUTTONS_NUMBER;
LinearLayout col0 = (LinearLayout)findViewById(R.layout.col0);
Button button = new Button(getContext()); // or create xml view for button and get it with findViewById

// adding buttons
for(int i = 0; i < buttonsNumber; i++)
    col0.addView(button);

// setting weight
TextView v0 = (TextView)findViewById(R.layout.v0);
v0.setLayoutParams(new TableLayout.LayoutParams(LayoutParams.match_parent, 0, buttonsNumber - 1));