AlertDialog.Builder is undefined
<p>Thought I had it working but I get another error! I'm still new to Android and can't seem to fix this issue no matter what. I know it's to do with using "new Builder(this);". However I don't know what else to use, any help would be appreciated!</p>

<pre><code>changeDay.setOnClickListener(new OnClickListener(){
        public void onClick(View v){
            AlertDialog.Builder b = new Builder(this);
            b.setTitle("Select Day");
            String[] types = {"1", "2", "3"};
            b.setItems(types, new DialogInterface.OnClickListener(){
                public void onClick(DialogInterface dialog, int    which){
                    dialog.dismiss();
                    switch(which){
                    case 0:
                        day = "1";
                        break;
                    case 1:
                        day = "2";
                        break;
                    }
                }
            }); 
        }
    });
</code></pre>
