Record Web Start Time

I try Date Class. I create app of "record web start time" to check Date Class.
The app have the time of pushing "Web Start" button.

I get now time.

SimpleDateFormat  sdf = new SimpleDateFormat("yyyy'　/'MM'/'dd'/ 'HH':'mm':'ss':'");  
Date  date = new Date();  

I get previous time of pushing "Web Start" button. I use SharedPreferences Class.

SharedPreferences pref = getSharedPreferences("pref", MODE_WORLD_READABLE|MODE_WORLD_WRITEABLE);
String votetime = pref.getString("votetime", sdf.format(date));

I preview previous time.

TextView prevvotetime = (TextView)findViewById(R.id.text1);
prevvotetime.setText(votetime);

If pushing "Web Start" button, I update time.
set listener.

Button votebutton = (Button)findViewById(R.id.button1);
votebutton.setOnClickListener(new View.OnClickListener() {

 @Override
 public void onClick(View v) {
 }
});

I update time and save time to SharedPreferences .

SimpleDateFormat  sdf = new SimpleDateFormat("yyyy'　/'MM'/'dd'/ 'HH':'mm':'ss':'");  
Date  date = new Date(); 

SharedPreferences pref = getSharedPreferences("pref", MODE_WORLD_READABLE|MODE_WORLD_WRITEABLE);
Editor e = pref.edit();
e.putString("votetime", sdf.format(date));
e.commit();

source code is here.
apk is here.
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