Android: ScrollView force to bottom

Question

I would like a ScrollView to start all the way at the bottom. Any methods?

Answer 1

you should run the code inside the scroll.post like this:

scroll.post(new Runnable() {            
    @Override
    public void run() {
           scroll.fullScroll(View.FOCUS_DOWN);              
    }
});

Answer 2

scroll.fullScroll(View.FOCUS_DOWN) also should work.

Put this in a scroll.Post(Runnable run)

Kotlin Code

scrollView.post {
   scrollView.fullScroll(View.FOCUS_DOWN)
}

Answer 3

scroll.fullScroll(View.FOCUS_DOWN) will lead to the change of focus. That will bring some strange behavior when there are more than one focusable views, e.g two EditText. There is another way for this question.

    View lastChild = scrollLayout.getChildAt(scrollLayout.getChildCount() - 1);
    int bottom = lastChild.getBottom() + scrollLayout.getPaddingBottom();
    int sy = scrollLayout.getScrollY();
    int sh = scrollLayout.getHeight();
    int delta = bottom - (sy + sh);

    scrollLayout.smoothScrollBy(0, delta);

This works well.

Kotlin Extension

fun ScrollView.scrollToBottom() {
    val lastChild = getChildAt(childCount - 1)
    val bottom = lastChild.bottom + paddingBottom
    val delta = bottom - (scrollY+ height)        
    smoothScrollBy(0, delta)
}

Or if you want to further enhance to check whether it is already at the bottom before scrolling, you can do something like this:

    fun ScrollView.scrollToBottom() {
    val lastChild = children.lastOrNull() ?: return
    val bottom = lastChild.bottom + paddingBottom
    val currentY = height + scrollY
    val alreadyAtBottom = bottom <= currentY
    if (!alreadyAtBottom) {
        val delta = bottom - currentY
        smoothScrollBy(0, delta)
    } else {
        // already at bottom, do nothing
    }
}

Answer 4

Sometimes scrollView.post doesn't work

 scrollView.post(new Runnable() {
        @Override
        public void run() {
            scrollView.fullScroll(ScrollView.FOCUS_DOWN);
        }
    });

BUT if you use scrollView.postDelayed, it will definitely work

 scrollView.postDelayed(new Runnable() {
        @Override
        public void run() {
            scrollView.fullScroll(ScrollView.FOCUS_DOWN);
        }
    },1000);

Answer 5

What worked best for me is

scroll_view.post(new Runnable() {
     @Override
     public void run() {
         // This method works but animates the scrolling 
         // which looks weird on first load
         // scroll_view.fullScroll(View.FOCUS_DOWN);

         // This method works even better because there are no animations.
         scroll_view.scrollTo(0, scroll_view.getBottom());
     }
});

Answer 6

I increment to work perfectly.

    private void sendScroll(){
        final Handler handler = new Handler();
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {Thread.sleep(100);} catch (InterruptedException e) {}
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                        scrollView.fullScroll(View.FOCUS_DOWN);
                    }
                });
            }
        }).start();
    }

---

Note

This answer is a workaround for really old versions of android. Today the postDelayed has no more that bug and you should use it.

Answer 7

i tried that successful.

scrollView.postDelayed(new Runnable() {
    @Override
    public void run() {
        scrollView.smoothScrollTo(0, scrollView.getHeight());
    }
}, 1000);

Answer 8

Here is some other ways to scroll to bottom

fun ScrollView.scrollToBottom() {
    // use this for scroll immediately
    scrollTo(0, this.getChildAt(0).height) 

    // or this for smooth scroll
    //smoothScrollBy(0, this.getChildAt(0).height)

    // or this for **very** smooth scroll
    //ObjectAnimator.ofInt(this, "scrollY", this.getChildAt(0).height).setDuration(2000).start()
}

Using

If you scrollview already laid out

my_scroll_view.scrollToBottom()

If your scrollview is not finish laid out (eg: you scroll to bottom in Activity onCreate method ...)

my_scroll_view.post { 
   my_scroll_view.scrollToBottom()          
}

Answer 9

When the view is not loaded yet, you cannot scroll. You can do it 'later' with a post or sleep call as above, but this is not very elegant.

It is better to plan the scroll and do it on the next onLayout(). Example code here:

https://stackoverflow.com/a/10209457/1310343

Answer 10

One thing to consider is what NOT to set. Make certain your child controls, especially EditText controls, do not have the RequestFocus property set. This may be one of the last interpreted properties on the layout and it will override gravity settings on its parents (the layout or ScrollView).

Answer 11

Not exactly the answer to the question, but I needed to scroll down as soon as an EditText got the focus. However the accepted answer would make the ET also lose focus right away (to the ScrollView I assume).

My workaround was the following:

emailEt.setOnFocusChangeListener(new View.OnFocusChangeListener() {
    @Override
    public void onFocusChange(View v, boolean hasFocus) {
        if(hasFocus){
            Toast.makeText(getActivity(), "got the focus", Toast.LENGTH_LONG).show();
            scrollView.postDelayed(new Runnable() {
                @Override
                public void run() {
                    scrollView.fullScroll(ScrollView.FOCUS_DOWN);
                }
            }, 200);
        }else {
            Toast.makeText(getActivity(), "lost the focus", Toast.LENGTH_LONG).show();
        }
    }
});

Answer 12

I actually found that calling fullScroll twice does the trick:

myScrollView.fullScroll(View.FOCUS_DOWN);

myScrollView.post(new Runnable() {
    @Override
    public void run() {
        myScrollView.fullScroll(View.FOCUS_DOWN);
    }
});

It may have something to do with the activation of the post() method right after performing the first (unsuccessful) scroll. I think this behavior occurs after any previous method call on myScrollView, so you can try replacing the first fullScroll() method by anything else that may be relevant to you.

Answer 13

Using there is another cool way to do this with Kotlin coroutines. The advantage of using a coroutine opposed to a Handler with a runnable (post/postDelayed) is that it does not fire up an expensive thread to execute a delayed action.

launch(UI){
    delay(300)
    scrollView.fullScroll(View.FOCUS_DOWN)
}

It is important to specify the coroutine's HandlerContext as UI otherwise the delayed action might not be called from the UI thread.

Answer 14

In those case were using just scroll.scrollTo(0, sc.getBottom()) don't work, use it using scroll.post

Example:

scroll.post(new Runnable() {
  @Override
  public void run() {
  scroll.fullScroll(View.FOCUS_DOWN);
  } 
});

Answer 15

One possible reason of why scroll.fullScroll(View.FOCUS_DOWN) might not work even wrapped in .post() is that the view is not laid out. In this case View.doOnLayout() could be a better option:

scroll.doOnLayout(){
    scroll.fullScroll(View.FOCUS_DOWN)
}

Or, something more elaborated for the brave souls: https://chris.banes.dev/2019/12/03/suspending-views/

Answer 16

If your minimum SDK is 29 or upper you could use this:

View childView = findViewById(R.id.your_view_id_in_the_scroll_view)
if(childView != null){
  scrollview.post(() -> scrollview.scrollToDescendant(childView));
}

Answer 17

A combination of all answers did the trick for me:

Extension Function PostDelayed

private fun ScrollView.postDelayed(
    time: Long = 325, // ms
    block: ScrollView.() -> Unit
) {
    postDelayed({block()}, time)
}

Extension Function measureScrollHeight

fun ScrollView.measureScrollHeight(): Int {
    val lastChild = getChildAt(childCount - 1)
    val bottom = lastChild.bottom + paddingBottom
    val delta = bottom - (scrollY+ height)
    return delta
}

Extension Function ScrolltoBottom

fun ScrollView.scrollToBottom() {
    postDelayed {
        smoothScrollBy(0, measureScrollHeight())
    }
}

Be aware that the minimum delay should be at least 325ms or the scrolling will be buggy (not scrolling to the entire bottom). The larger your delta between the current height and the bottom is, the larger should be the delayed time.

Answer 18

Some people here said that scrollView.post didn't work.

If you don't want to use scrollView.postDelayed, another option is to use a listener. Here is what I did in another use case :

ViewTreeObserver.OnPreDrawListener viewVisibilityChanged = new ViewTreeObserver.OnPreDrawListener() {
    @Override
    public boolean onPreDraw() {
        if (my_view.getVisibility() == View.VISIBLE) {
            scroll_view.smoothScrollTo(0, scroll_view.getHeight());
        }
        return true;
    }
};

You can add it to your view this way :

my_view.getViewTreeObserver().addOnPreDrawListener(viewVisibilityChanged);

Answer 19

This works instantly. Without delay.

// wait for the scroll view to be laid out
scrollView.post(new Runnable() {
  public void run() {
    // then wait for the child of the scroll view (normally a LinearLayout) to be laid out
    scrollView.getChildAt(0).post(new Runnable() {
      public void run() {
        // finally scroll without animation
        scrollView.scrollTo(0, scrollView.getBottom());
      }
    }
  }
}