android back to privious activity

// showProgressDialog();

// bind events 

billButton = (Button) findViewById(R.id.billing);

billButton.setOnClickListener(this);

cancelbillButton = (Button) findViewById(R.id.cancelbilling);

cancelbillButton.setOnClickListener(this);

public void onClick(View v) {

int id = v.getId();

switch (id) {

case R.id.billing:

/**

* 商品购买接口。

*/

order(this,mListener);

break;

case R.id.cancelbilling:

this.finish(); // back  

break;

default:

break;

}