Animate ProgressBar update in Android

I used android Animation for this:

public class ProgressBarAnimation extends Animation{
    private ProgressBar progressBar;
    private float from;
    private float  to;

    public ProgressBarAnimation(ProgressBar progressBar, float from, float to) {
        super();
        this.progressBar = progressBar;
        this.from = from;
        this.to = to;
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        super.applyTransformation(interpolatedTime, t);
        float value = from + (to - from) * interpolatedTime;
        progressBar.setProgress((int) value);
    }

}

and call it like so:

ProgressBarAnimation anim = new ProgressBarAnimation(progress, from, to);
anim.setDuration(1000);
progress.startAnimation(anim);

Note: if from and to value are too low to produce smooth animation just multiply them by a 100 or so. If you do so, don't forget to multiply setMax(..) as well.

I use an ObjectAnimator

private ProgressBar progreso;
private ObjectAnimator progressAnimator;
progreso = (ProgressBar)findViewById(R.id.progressbar1);
progressAnimator = ObjectAnimator.ofInt(progreso, "progress", 0,1);
progressAnimator.setDuration(7000);
progressAnimator.start();

The simplest way, using ObjectAnimator (both Java and Kotlin):

ObjectAnimator.ofInt(progressBar, "progress", progressValue)
    .setDuration(300)
    .start();

where progressValue is integer within range 0-100 (the upper limit is set to 100 by default but you can change it with Progressbar#setMax() method)

You can also change the way how values are changing by setting different interpolator with setInterpolator() method. Here is visualization of different interpolators: https://www.youtube.com/watch?v=6UL7PXdJ6-E

Here is an improved version of @Eli Konky solution:

public class ProgressBarAnimation extends Animation {
    private ProgressBar mProgressBar;
    private int mTo;
    private int mFrom;
    private long mStepDuration;

    /**
     * @param fullDuration - time required to fill progress from 0% to 100%
     */
    public ProgressBarAnimation(ProgressBar progressBar, long fullDuration) {
        super();
        mProgressBar = progressBar;
        mStepDuration = fullDuration / progressBar.getMax();
    }


    public void setProgress(int progress) {
        if (progress < 0) {
            progress = 0;
        }

        if (progress > mProgressBar.getMax()) {
            progress = mProgressBar.getMax();
        }

        mTo = progress;

        mFrom = mProgressBar.getProgress();
        setDuration(Math.abs(mTo - mFrom) * mStepDuration);
        mProgressBar.startAnimation(this);
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        float value = mFrom + (mTo - mFrom) * interpolatedTime;
        mProgressBar.setProgress((int) value);
    }
}

And usage:

ProgressBarAnimation mProgressAnimation = new ProgressBarAnimation(mProgressBar, 1000);
...

/* Update progress later anywhere in code: */
mProgressAnimation.setProgress(progress);

ProgressBar().setProgress(int progress, boolean animate)

Android has taken care of that for you