Try the following changes, they worked for me:
long offset = 0;
start.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
focus.setBase(SystemClock.elapsedRealtime() - offset);
focus.start();
start.setEnabled(false);
reset.setEnabled(false);
stop.setEnabled(true);
}
});
stop.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
focus.stop();
offset = SystemClock.elapsedRealtime() - focus.getBase();
start.setEnabled(true);
stop.setEnabled(false);
reset.setEnabled(true);
}
});
reset.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
focus.setBase(SystemClock.elapsedRealtime());
offset = 0;
reset.setEnabled(false);
}
});