动态添加按钮以滚动视图

Question

I would like some help with dynamically adding buttons to a ScrollView . I've got it working with a LinearLayout but obviously I can only add so many buttons before they no longer appear on screen. My code is below with an attached image of its current state.

I tried changing every occurrence of LinearLayout with ScrollView in the code but when I ran it, I got an error that stated something along the lines of ScrollViews can only have 1 direct child .

I'm not sure how to make it work, so if someone could give me some guidance on how to do it, I would be very grateful.

My XML Code:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"

    <LinearLayout
        android:id="@+id/mainLayout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_below="@id/imageTextView"
        android:layout_centerHorizontal="true">
    </LinearLayout>

</RelativeLayout>

My Java Code (where I'm dynamically creating the buttons):

public class Main5Activity extends AppCompatActivity
{

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main5);

        LinearLayout layout = (LinearLayout) findViewById(R.id.mainLayout);

        for (int i = 0; i < 6; i++)
        {
            LinearLayout row = new LinearLayout(this);
            row.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));

            for (int j = 0; j < 4; j++)
            {
                final Button btnTag = new Button(this);
                btnTag.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT));
                btnTag.setText("" + (j + 1 + (i * 4)));
                btnTag.setId(j + 1 + (i * 4));
                row.addView(btnTag);
            }
            layout.addView(row);
        }
    }
}

Image of the current layout.

Answer 1

Yes ScrollView can only have 1 child, and often it is the ViewGroup like LinearLayout , RelativeLayout , etc. You need to wrap your LinearLayout with a ScrollView , like this:

<ScrollView>
    <LinearLayout
    android:id="@+id/mainLayout"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:layout_below="@id/imageTextView"
    android:layout_centerHorizontal="true"/>
</ScrollView>

Or you can change your topmost RelativeLayout into ScrollView if it has only one child.