android 简单的计算器

package com.example.calculator;  import java.util.Arrays; import bsh.EvalError;import bsh.Interpreter;import android.os.Bundle;import android.app.Activity;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText; /** * @author 铂金小龟  */public class CalculatorActivity extends Activity implements OnClickListener{     EditText rsText = null;  //显示器    boolean isClear = false; //用于是否显示器需要被清理    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.calculator);                 //fun 功能按钮        rsText = (EditText)findViewById(R.id.rsText);        Button btnDel = (Button)findViewById(R.id.delete);        Button btnPlu = (Button)findViewById(R.id.plus);        Button btnMin = (Button)findViewById(R.id.minus);        Button btnMul = (Button)findViewById(R.id.multiply);        Button btnDiv = (Button)findViewById(R.id.division);        Button btnEqu = (Button)findViewById(R.id.equ);        Button btnTono = (Button)findViewById(R.id.tonone);        Button btnLeft = (Button)findViewById(R.id.left);        Button btnRight = (Button)findViewById(R.id.right);                 //num 数字按钮        Button num0 = (Button)findViewById(R.id.num0);        Button num1 = (Button)findViewById(R.id.num1);        Button num2 = (Button)findViewById(R.id.num2);        Button num3 = (Button)findViewById(R.id.num3);        Button num4 = (Button)findViewById(R.id.num4);        Button num5 = (Button)findViewById(R.id.num5);        Button num6 = (Button)findViewById(R.id.num6);        Button num7 = (Button)findViewById(R.id.num7);        Button num8 = (Button)findViewById(R.id.num8);        Button num9 = (Button)findViewById(R.id.num9);        Button dot = (Button)findViewById(R.id.dot);                 //listener        btnTono.setOnClickListener(this);        btnLeft.setOnClickListener(this);        btnRight.setOnClickListener(this);        btnDel.setOnClickListener(this);        btnPlu.setOnClickListener(this);        btnMin.setOnClickListener(this);        btnMul.setOnClickListener(this);        btnDiv.setOnClickListener(this);        btnEqu.setOnClickListener(this);          num0.setOnClickListener(this);          num1.setOnClickListener(this);          num2.setOnClickListener(this);          num3.setOnClickListener(this);          num4.setOnClickListener(this);          num5.setOnClickListener(this);          num6.setOnClickListener(this);          num7.setOnClickListener(this);          num8.setOnClickListener(this);          num9.setOnClickListener(this);          dot.setOnClickListener(this);    }     @Override    public void onClick(View e) {        Button btn = (Button)e;        String exp = rsText.getText().toString();        if(isClear &&(              btn.getText().equals("0")            ||btn.getText().equals("1")            ||btn.getText().equals("2")            ||btn.getText().equals("3")            ||btn.getText().equals("4")            ||btn.getText().equals("5")            ||btn.getText().equals("6")            ||btn.getText().equals("7")            ||btn.getText().equals("8")            ||btn.getText().equals("9")            ||btn.getText().equals("."))         ||btn.getText().equals("算数公式错误")){            rsText.setText("");            isClear = false;        }        if(btn.getText().equals("C")){            rsText.setText("");        }else if(btn.getText().equals("清除")){             if(isEmpty(exp)) return;            else                rsText.setText(exp.substring(0, exp.length()-1));        }else if(btn.getText().equals("=")){            if(isEmpty(exp)) return;            exp = exp.replaceAll("×", "*");            exp = exp.replaceAll("÷", "/");            rsText.setText(getRs(exp));             isClear = false;        }else{            rsText.setText(rsText.getText()+""+btn.getText());            isClear = false;        }        //操作完成后始终保持光标在最后一位        rsText.setSelection(rsText.getText().length());    }     /***     * @param  exp 算数表达式     * @return 根据表达式返回结果     */    private String getRs(String exp){            Interpreter bsh = new Interpreter();            Number result = null;            try {                exp = filterExp(exp);                result = (Number)bsh.eval(exp);            } catch (EvalError e) {                e.printStackTrace();                isClear = true;                return "算数公式错误";            }                    exp = result.doubleValue()+"";            if(exp.endsWith(".0"))                exp = exp.substring(0, exp.indexOf(".0"));            return exp;    }              /**     * 因为计算过程中,全程需要有小数参与,所以需要过滤一下     * @param exp 算数表达式     * @return      */    private String filterExp(String exp) {        String num[] = exp.split("");        String temp = null;        int begin=0,end=0;         for (int i = 1; i < num.length; i++) {             temp = num[i];             if(temp.matches("[+-/()*]")){                 if(temp.equals(".")) continue;                 end = i - 1;                   temp = exp.substring(begin, end);                 if(temp.trim().length() > 0 && temp.indexOf(".")<0)                     num[i-1] = num[i-1]+".0";                 begin = end + 1;             }         }         return Arrays.toString(num).replaceAll("[\\[\\], ]", "");    }         /***     * @param str     * @return 字符串非空验证     */    private boolean isEmpty(String str){        return (str==null || str.trim().length()==0);    }     }