EditText输入数据精确到小数点后n位

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
>

<EditText
android:id="@+id/et"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="30dp"
android:gravity="center"
android:hint="请输入"
android:inputType="numberDecimal"
android:textSize="20sp"
/>

</RelativeLayout>

public class MainActivity extends Activity {

EditText et;
/**
* 用于控制小数点后面的位数。这里默认设置，如果输入了小数点，后面最多只能有1位
*/
private static final int ACCURACYNUM = 1;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

et = (EditText) findViewById(R.id.et);

et.addTextChangedListener(watcher);
}

private TextWatcher watcher = new TextWatcher() {
@Override
public void afterTextChanged(Editable s) {
// TODO Auto-generated method stub
String temp = s.toString().trim();
//如果数据以小数点开头，就清空。因为手机的处理速度，怎么也比手动输入的速度快，所以给人感觉是：开头输小数点，输不进去
if (s.toString().startsWith(".")) {
et.setText("");
}

int posDot = temp.indexOf(".");
if (posDot <= 0)
return;
if (temp.length() - posDot - 1 > ACCURACYNUM) {
s.delete(posDot + ACCURACYNUM + 1, posDot + ACCURACYNUM + 2);
}
}

@Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
}

@Override
public void onTextChanged(CharSequence s, int start, int before,
int count) {
}
};

}