Change the Color of ScrollView Programmatically
android, android-scrollview, android-xml
Solution
There is a method to change it programmatically but that method is not exposed. There doesn't seem to be anything else to change it programmatically from what I have read.
However, I did come across this one stackoverflow answer that uses reflection to do it. Please upvote the answer there if it works for you: https://stackoverflow.com/a/19819843/3286163
The answer was for a listview but is the same for the scrollview:
ScrollView scr = (ScrollView)findViewById(R.id.scrollView1);
try
{
Field mScrollCacheField = View.class.getDeclaredField("mScrollCache");
mScrollCacheField.setAccessible(true);
Object mScrollCache = mScrollCacheField.get(scr); // scr is your Scroll View
Field scrollBarField = mScrollCache.getClass().getDeclaredField("scrollBar");
scrollBarField.setAccessible(true);
Object scrollBar = scrollBarField.get(mScrollCache);
Method method = scrollBar.getClass().getDeclaredMethod("setVerticalThumbDrawable", Drawable.class);
method.setAccessible(true);
// Set your drawable here.
method.invoke(scrollBar, getResources().getDrawable(R.drawable.scrollbar_blue));
}
catch(Exception e)
{
e.printStackTrace();
}
Only thing I could find. I gave it a try myself and it worked.
Problem
What I'm currently doing Currently, I have changed the scrollbar in my XML file using the `android:scrollbarThumbVertical` property like so: ``` <ScrollView android:id="@+id/scrollView1" android:scrollbarThumbVertical="@drawable/scrollbar_blue" ... > ``` And `scrollbar_blue` refers to my `scrollbar_blue.xml` file, which is this: ``` <?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" > <gradient android:angle="45" android:centerColor="@color/blue" android:endColor="@color/blue" android:startColor="@color/blue" /> <corners android:radius="8dp" /> </shape> ``` What I want to do I have a colour option for my app - so when the colour is on, it should stay blue; otherwise, it should be grey. How can I programmatically (in my activity class) change my ScrollView to use my `scrollbar_grey.xml`? If you look at the Android documentation on `ScrollView`, there is no corresponding method to `android:scrollbarThumbVertical` I'm fine with another way change the colour as well. Here is how I create the reference to my ScrollView: ``` ScrollView scr = (ScrollView)findViewById(R.id.scrollView1); ```