TextView problem

[techcent]

Hi Friends

I am new one in the world of Android, i wrote a sample application code from internet. I can't run application it shows an error

please find code snippet

alert.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
String value = input.getText().toString();
TextView tv = new TextView(this);
alert.setView(tv);
}
});


Error is "The constructor TextView(new DialogInterface.OnClickListener(){}) is undefined"

expecting your valuable help

thanks in advance