import android.view.animation.AccelerateInterpolator;
import android.view.animation.Interpolator;
import android.widget.TextView;

public class CountingHelper implements Runnable {

    private final long mDuration;
    private final int mStartingValue;
    private final int mFinalValue;

    private final TextView mTextView;

    private final int mValueRange;

    private long mProgressTime = 0;
    private long mLastUpdateTime = 0;


    private Interpolator mInterpolator = new AccelerateInterpolator();

    public CountingHelper(int startingValue, int finalValue, int duration, TextView textView) {
        mDuration = duration;
        mStartingValue = startingValue;
        mFinalValue = finalValue;
        mTextView = textView;

        mValueRange = mFinalValue - mStartingValue;

        mLastUpdateTime = System.currentTimeMillis();
    }

    @Override
    public void run() {
        long now = System.currentTimeMillis();
        mProgressTime += (now - mLastUpdateTime);
        boolean shouldSchedule = true;
        if (mProgressTime >= mDuration) {
            mProgressTime = mDuration;
            shouldSchedule = false;
        }
        mTextView.setText(String.valueOf(getCurrentValue()));
        if (shouldSchedule) {
            mTextView.postOnAnimation(this);
        }
    }

    private int getCurrentValue() {
        if (mProgressTime >= mDuration) {
            return mFinalValue;
        }
        return (int) (mStartingValue + (mInterpolator.getInterpolation(
                (float) mProgressTime / (float) mDuration) * mValueRange));
    }
}