Android入门--写一个最简单的计算器

<?xml version="1.0" encoding="utf-8"?>http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> @+id/editText1" android:text="@string/hello"  android:digits="1234567890.+-*/%/n/t()" android:layout_width="match_parent"  android:layout_height="match_parent">

package ghj1976.HelloWorld;import bsh.EvalError;import bsh.Interpreter;import android.app.Activity;import android.os.Bundle;import android.view.KeyEvent;import android.widget.EditText;public class HelloWorldActivity extends Activity {     private static EditText et; private static Interpreter i = new Interpreter();  /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        et = (EditText)findViewById(R.id.editText1);        et.append("/n");        et.setSelection(et.length()); // 调整光标到最后一行      }        @Override    public boolean onKeyUp(int keyCode,KeyEvent event)    {     // 判断是否输入了回车     if(keyCode == KeyEvent.KEYCODE_ENTER)     {      String input = et.getText().toString();      // 这里用偷懒的方式取用户最后一行输入      String lastLine = input.substring(input.lastIndexOf("/n",input.length() - 2));      et.append("/t/t");      et.append(eval(lastLine)+"/n");      et.setSelection(et.length());     }     return true;    }           // 用 beanshell 偷懒来做算式计算    private Object eval(String input)    {     try     {      return i.eval(input);     }     catch(EvalError e)     {      return e.getMessage();           }         }  }