用Eslipse开发Android案例（1）——计算器<part1>

程序下来链接：http://pan.baidu.com/s/1slvI4f7

主程序：

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package com.example;

import com.example.R.id;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

//import android.view.View.OnClickListener;

public class MainActivity extends Activity implements View.OnClickListener {
private Button add; //按钮+
private Button subtract; //按钮-
private Button multiply; //按钮*
private Button divide; //按钮/
private Button equal; //按钮=
private Button delete; //按钮删除一个输入的符号
private Button clear; //按钮用来清除输入框
private Button point; //按钮小数点

private Button one;         //按钮1private Button two;private Button three;private Button four;private Button five;private Button six;private Button seven;private Button eight;private Button nine;private Button zero;private EditText showtext;//用来显示输入的符号和数字private String OperateSum="";//字符串用来保存输入的数字和符号private char Operator;      //用来记录运算符号private double num1=0,num2=0,sum=0;     //num1,num2记录输入的数字，sum保存运算的结果//private boolean NewCalculate=true;@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    initView();//对按钮和事件进行初始化}private void initView(){    one=(Button) findViewById(R.id.one);    two=(Button) findViewById(R.id.two);    three=(Button) findViewById(R.id.three);    four=(Button) findViewById(R.id.four);    five=(Button) findViewById(R.id.five);    six=(Button) findViewById(R.id.six);    seven=(Button) findViewById(R.id.seven);    eight=(Button) findViewById(R.id.eight);    nine=(Button) findViewById(R.id.nine);    zero=(Button) findViewById(R.id.zero);    add=(Button) findViewById(R.id.plus);    subtract=(Button) findViewById(R.id.减号);    multiply=(Button) findViewById(R.id.乘号);    divide=(Button) findViewById(R.id.除号);    delete=(Button) findViewById(R.id.删除);    clear=(Button) findViewById(R.id.clear);    equal=(Button) findViewById(R.id.equal);    point=(Button) findViewById(R.id.point);    //about=(Button) findViewById(R.id.about);    showtext=(EditText) findViewById(R.id.text);    showtext.setCursorVisible(false);    zero.setOnClickListener(this);//添加按钮事件    one.setOnClickListener(this);    two.setOnClickListener(this);    three.setOnClickListener(this);    four.setOnClickListener(this);    five.setOnClickListener(this);    six.setOnClickListener(this);    seven.setOnClickListener(this);    eight.setOnClickListener(this);    nine.setOnClickListener(this);    add.setOnClickListener(this);    subtract.setOnClickListener(this);    multiply.setOnClickListener(this);    divide.setOnClickListener(this);    equal.setOnClickListener(this);    delete.setOnClickListener(this);    clear.setOnClickListener(this);    point.setOnClickListener(this);    //about.setOnClickListener(this);    showtext.setOnClickListener(this);}private Button findViewById(Class<id> class1) {    // TODO Auto-generated method stub    return null;}@Overridepublic void onClick(View v) {    switch (v.getId()) {        case R.id.one:      //记录输入的数字1            OperateSum=AddSum('1');//把数字添加进OperateSum            showtext.setText(OperateSum);   //把输入的数字显示在EditText            break;        case R.id.two:      //记录输入的数字2            OperateSum=AddSum('2');            showtext.setText(OperateSum);            break;        case R.id.three:            OperateSum=AddSum('3');            showtext.setText(OperateSum);            break;        case R.id.four:            OperateSum=AddSum('4');            showtext.setText(OperateSum);            break;        case R.id.five:            OperateSum=AddSum('5');            showtext.setText(OperateSum);            break;        case R.id.six:            OperateSum=AddSum('6');            showtext.setText(OperateSum);            break;        case R.id.seven:            OperateSum=AddSum('7');            showtext.setText(OperateSum);            break;        case R.id.eight:            OperateSum=AddSum('8');            showtext.setText(OperateSum);            break;        case R.id.nine:            OperateSum=AddSum('9');            showtext.setText(OperateSum);            break;        case R.id.zero:            OperateSum=AddSum('0');            showtext.setText(OperateSum);            break;        case R.id.plus:      //记录+号            OperateSum=AddSum('+');            Operator='+';       //记录加法            showtext.setText(OperateSum);   //把输入的+号显示在EditText            break;        case R.id.减号:            OperateSum=AddSum('-');            Operator='-';            showtext.setText(OperateSum);            break;        case R.id.乘号:            OperateSum=AddSum('*');            Operator='*';            showtext.setText(OperateSum);            break;        case R.id.除号:            OperateSum=AddSum('/');            Operator='/';            showtext.setText(OperateSum);            break;        case R.id.point:            OperateSum=AddSum('.');            showtext.setText(OperateSum);            break;        case R.id.删除:       //删除刚刚输入的一个符号            if(OperateSum.length()>=1)//当至少已经输入了一个符号才执行            {                OperateSum=OperateSum.substring(0,OperateSum.length()-1);            }            showtext.setText(OperateSum);            break;        case R.id.clear:        //清除整个显示框            OperateSum="";      //变量全部初始化            num1=0;            num2=0;            sum=0;            Operator=' ';            showtext.setText(OperateSum);            break;        case R.id.equal:            if(CheckInput(OperateSum))//当输入的数字和运算符都正确，才进行计算            {                OperateSum=OperateSum+"="+String.valueOf(equals(OperateSum));                showtext.setText(OperateSum);//显示数字运算符和结果                OperateSum=String.valueOf(sum); //保存运算结果，以便再直接输入一个运算符和一个数字进行下一次运算            }            else                        //输入不合理弹出警告            {                Toast.makeText(this,"Error", Toast.LENGTH_SHORT).show();            }            break;        default:            break;    }}public String AddSum(char c)//添加并记录一个输入的数字或符号{    OperateSum=OperateSum+String.valueOf(c);    return OperateSum;}public boolean CheckInput(String OperateSum)    //这个方法用来检查用户输入的数字是否合理，比如用户输入了"9/3"这是合理的，加入输入了 " 8/*",这部合理{    if(OperateSum.length()<=2)//至少要分别输入了一个数字和一个运算符和一个数字，输入长度<=2肯定不合理，如输入 99 按下=按钮肯定不计算    {        return false;    }    if(OperateSum.indexOf(Operator, 1)==-1)     //如果没有输入运算符，肯定不合理    {        return false;    }    if(OperateSum.endsWith(String.valueOf(Operator)))       //最后以运算符结尾而不是数字，肯定不合理 如输入 9** ，不进行计算    {        return false;    }    return true;}public double equals(String OperateSum)         //计算结果{    int indexOfOperator=0;    indexOfOperator=OperateSum.indexOf(Operator,1);         //计算运算符在从输入的OperateSum字符串里的位置    if(OperateSum.length()>=3)    {        num1=Double.parseDouble(OperateSum.substring(0, indexOfOperator));  //从输入的OperateSum字符串里得到第一个运算数        num2=Double.parseDouble(OperateSum.substring(indexOfOperator + 1, OperateSum.length()));    //从输入的OperateSum字符串里得到第二个运算数    }    switch (Operator)       //根据运算符进行计算    {        case '+':           //加法运算            sum=num1+num2;            break;        case '-':           //减法运算            sum=num1-num2;            break;        case '*':           //乘法运算            sum=num1*num2;            break;        case '/':           //除法运算            if(num2!=0)     //除数不应该为0            {                sum=num1/num2;            }            else            {                sum=0;                Toast.makeText(this,"Error", Toast.LENGTH_LONG).show();//若除数是0，弹出警告            }            break;        default:            break;    }    return sum;         //返回结果}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {    // Inflate the menu; this adds items to the action bar if it is present.    getMenuInflater().inflate(R.menu.menu, menu);    return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {    // Handle action bar item clicks here. The action bar will    // automatically handle clicks on the Home/Up button, so long    // as you specify a parent activity in AndroidManifest.xml.    int id = item.getItemId();    //noinspection SimplifiableIfStatement    if (id == R.id.action_settings) {        return true;    }    return super.onOptionsItemSelected(item);}

}

//机智勇敢的李小白“`

layout：