android 提示对话框显示 AlertDialog

AlertDialog.Builder delContactDialog = new Builder(getApplicationContext());
delContactDialog.setIcon(R.drawable.ic_launcher).setTitle(R.string.dialog_warning)
.setMessage(R.string.dialog_warning_msg);
delContactDialog.setPositiveButton(R.string.dialog_ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int whichbtn) {
//to do
}
});
delContactDialog.setNegativeButton(R.string.dialog_cancel, new DialogInterface.OnClickListener(){

@Override
public void onClick(DialogInterface dialog, int whichbtn) {
dialog.dismiss();
}

});