android实现计算器（慕课网视频教学）

网址：http://www.imooc.com/video/3071

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <EditText        android:layout_width="fill_parent"        android:layout_height="60dip"        android:background="@drawable/whitebg"        android:editable="false"        android:id="@+id/et_showview"        android:gravity="bottom|right"        android:textSize="20sp" />    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="fill_parent"        android:layout_marginTop="20dip"        android:gravity="center_horizontal"        android:orientation="vertical" >        <LinearLayout            android:layout_width="fill_parent"            android:layout_height="wrap_content"            android:gravity="center_horizontal"            android:orientation="horizontal" >            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                android:id="@+id/btn_clear"                android:background="@drawable/white_btn_selector"                android:text="C" />            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:layout_marginLeft="10dip"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                android:id="@+id/btn_del"                android:background="@drawable/white_btn_selector"                android:text="DEL" />            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:layout_marginLeft="10dip"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                android:id="@+id/btn_divide"                android:background="@drawable/white_btn_selector"                android:text="÷" />            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:layout_marginLeft="10dip"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                 android:id="@+id/btn_multiply"                android:background="@drawable/white_btn_selector"                android:text="×" />        </LinearLayout>        <LinearLayout            android:layout_width="fill_parent"            android:layout_height="wrap_content"            android:layout_marginTop="10dip"            android:gravity="center_horizontal"            android:orientation="horizontal" >            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                 android:id="@+id/btn_7"                android:background="@drawable/white_btn_selector"                android:text="7" />            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:layout_marginLeft="10dip"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                 android:id="@+id/btn_8"                android:background="@drawable/white_btn_selector"                android:text="8" />            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:layout_marginLeft="10dip"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                android:id="@+id/btn_9"                android:background="@drawable/white_btn_selector"                android:text="9" />            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:layout_marginLeft="10dip"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                android:id="@+id/btn_minus"                android:background="@drawable/white_btn_selector"                android:text="－" />        </LinearLayout>        <LinearLayout            android:layout_width="fill_parent"            android:layout_height="wrap_content"            android:layout_marginTop="10dip"            android:gravity="center_horizontal"            android:orientation="horizontal" >            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                android:id="@+id/btn_4"                android:background="@drawable/white_btn_selector"                android:text="4" />            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:layout_marginLeft="10dip"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                android:id="@+id/btn_5"                android:background="@drawable/white_btn_selector"                android:text="5" />            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:layout_marginLeft="10dip"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                 android:id="@+id/btn_6"                android:background="@drawable/white_btn_selector"                android:text="6" />            <Button                android:layout_width="60dp"                android:layout_height="60dp"                android:layout_marginLeft="10dip"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                android:id="@+id/btn_pluse"                android:background="@drawable/white_btn_selector"                android:text="＋" />        </LinearLayout>        <LinearLayout            android:layout_width="fill_parent"            android:layout_height="wrap_content"            android:layout_marginTop="10dip"            android:gravity="center_horizontal"            android:orientation="horizontal" >            <LinearLayout                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:orientation="vertical" >                <LinearLayout                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:orientation="horizontal" >                    <Button                        android:layout_width="60dp"                        android:layout_height="60dp"                        android:gravity="bottom|right"                        android:paddingBottom="10dp"                        android:paddingRight="10dp"                        android:textSize="20sp"                        android:id="@+id/btn_1"                        android:background="@drawable/white_btn_selector"                        android:text="1" />                    <Button                        android:layout_width="60dp"                        android:layout_height="60dp"                        android:layout_marginLeft="10dip"                        android:gravity="bottom|right"                        android:paddingBottom="10dp"                        android:paddingRight="10dp"                        android:textSize="20sp"                        android:id="@+id/btn_2"                        android:background="@drawable/white_btn_selector"                        android:text="2" />                    <Button                        android:layout_width="60dp"                        android:layout_height="60dp"                        android:layout_marginLeft="10dip"                        android:gravity="bottom|right"                        android:paddingBottom="10dp"                        android:paddingRight="10dp"                        android:textSize="20sp"                        android:id="@+id/btn_3"                        android:background="@drawable/white_btn_selector"                        android:text="3" />                </LinearLayout>                <LinearLayout                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:layout_marginTop="10dip"                    android:orientation="horizontal" >                    <Button                        android:layout_width="130dp"                        android:layout_height="60dp"                        android:gravity="bottom|right"                        android:paddingBottom="10dp"                        android:paddingRight="10dp"                        android:textSize="20sp"                        android:id="@+id/btn_0"                        android:background="@drawable/white_btn_selector"                        android:text="0" />                    <Button                        android:layout_width="60dp"                        android:layout_height="60dp"                        android:layout_marginLeft="10dip"                        android:gravity="bottom|right"                        android:paddingBottom="10dp"                        android:paddingRight="10dp"                        android:text="."                         android:id="@+id/btn_point"                        android:background="@drawable/white_btn_selector"                        android:textSize="20sp"/>                </LinearLayout>            </LinearLayout>            <Button                android:layout_width="60dip"                android:layout_height="130dip"                android:layout_marginLeft="10dip"                android:gravity="bottom|right"                android:paddingBottom="10dp"                android:paddingRight="10dp"                android:textSize="20sp"                android:id="@+id/btn_equal"                android:background="@drawable/orange_btn_selector"                android:text="=" />        </LinearLayout>    </LinearLayout></LinearLayout>

package com.imooc.calculator;import java.util.ArrayList;import java.util.Arrays;import bsh.EvalError;import bsh.Interpreter;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;public class MainActivity extends Activity implements OnClickListener {Button btn_0;Button btn_1;Button btn_2;Button btn_3;Button btn_4;Button btn_5;Button btn_6;Button btn_7;Button btn_8;Button btn_9;Button btn_point;// 小数点Button btn_divide;// 除以Button btn_multiply;// 乘以Button btn_minus;// 减去Button btn_pluse;// 加Button btn_equal;// 等于Button btn_clear;Button btn_del;EditText et_showview;boolean needclear;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);btn_0 = (Button) findViewById(R.id.btn_0);btn_1 = (Button) findViewById(R.id.btn_1);btn_2 = (Button) findViewById(R.id.btn_2);btn_3 = (Button) findViewById(R.id.btn_3);btn_4 = (Button) findViewById(R.id.btn_4);btn_5 = (Button) findViewById(R.id.btn_5);btn_6 = (Button) findViewById(R.id.btn_6);btn_7 = (Button) findViewById(R.id.btn_7);btn_8 = (Button) findViewById(R.id.btn_8);btn_9 = (Button) findViewById(R.id.btn_9);btn_point = (Button) findViewById(R.id.btn_point);// 小数点btn_divide = (Button) findViewById(R.id.btn_divide);// 除以btn_multiply = (Button) findViewById(R.id.btn_multiply);// 乘以btn_minus = (Button) findViewById(R.id.btn_minus);// 减去btn_pluse = (Button) findViewById(R.id.btn_pluse);// 加btn_equal = (Button) findViewById(R.id.btn_equal);// 等于btn_clear = (Button) findViewById(R.id.btn_clear);btn_del = (Button) findViewById(R.id.btn_del);et_showview = (EditText) findViewById(R.id.et_showview);btn_0.setOnClickListener(this);btn_1.setOnClickListener(this);btn_2.setOnClickListener(this);btn_3.setOnClickListener(this);btn_4.setOnClickListener(this);btn_5.setOnClickListener(this);btn_6.setOnClickListener(this);btn_7.setOnClickListener(this);btn_8.setOnClickListener(this);btn_9.setOnClickListener(this);btn_point.setOnClickListener(this);btn_divide.setOnClickListener(this);btn_multiply.setOnClickListener(this);btn_minus.setOnClickListener(this);btn_pluse.setOnClickListener(this);btn_equal.setOnClickListener(this);btn_clear.setOnClickListener(this);btn_del.setOnClickListener(this);}@Overridepublic void onClick(View v) {// TODO Auto-generated method stubString str = et_showview.getText().toString();switch (v.getId()) {case R.id.btn_0:case R.id.btn_1:case R.id.btn_2:case R.id.btn_3:case R.id.btn_4:case R.id.btn_5:case R.id.btn_6:case R.id.btn_7:case R.id.btn_8:case R.id.btn_9:case R.id.btn_point:if(needclear){str = "";et_showview.setText("");}et_showview.setText(str + ((Button) v).getText());break;case R.id.btn_pluse:case R.id.btn_minus:case R.id.btn_multiply:case R.id.btn_divide:if(needclear){et_showview.setText("");}et_showview.setText(str +" "+((Button) v).getText()+" ");break;case R.id.btn_equal:getResult();break;case R.id.btn_del:if (str != null && !str.equals("")) {et_showview.setText(str.substring(0, str.length() - 1));}break;case R.id.btn_clear:et_showview.setText("");break;}}/** * 获取计算结果 */private void getResult() {needclear = true;String exp = et_showview.getText().toString();double r = 0;    int space = exp.indexOf(' ');//用于搜索空格位置        String s1 = exp.substring(0, space);//s1用于保存第一个运算数        String op = exp.substring(space + 1, space + 2);//op用于保存运算符        String s2 = exp.substring(space + 3);//s2用于保存第二个运算数        double arg1 = Double.parseDouble(s1);//将运算数从string转换为Single        double arg2 = Double.parseDouble(s2);        if(op.equals("＋")){         r = arg1 + arg2;        }else if(op.equals("－")){        r = arg1 - arg2;        }else if(op.equals("×")){         r = arg1 * arg2;        }else if(op.equals("÷")){         if (arg2 == 0)             {                r=0;             }             else             {                 r = arg1 / arg2;             }        }               if(!s1.contains(".")&&!s2.contains(".")){        int result = (int)r;        et_showview.setText(result+"");        }else{        et_showview.setText(r+"");        }}/////***// * @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();//return "0";//}//return result.doubleValue() + "";//}/////**// * @param exp// *            算数表达式// * @return 因为计算过程中,全程需要有小数参与.// *///private String filterExp(String exp) {//String num[] = exp.split("");//String temp = null;//double dtemp = 0 ;//String str_temp="";//for (int i = 0; i < num.length; i++) {//temp = num[i];////if (temp.equals("+") || temp.equals("-") || temp.equals("×")//|| temp.equals("÷")) {//if(dtemp==0){//dtemp=Double.parseDouble(str_temp);//}////str_temp="";//}else{//str_temp=str_temp+temp;//}//}////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("[\\[\\], ]", "");//}}