实现了四则运算，是学习的好资料
界面布局采用TableRow进行布局，采用自定义的style进行背景颜色设置，点击按钮又会变换颜色
资源文件列表
calculator/.classpath , 364
calculator/.project , 846
calculator/AndroidManifest.xml , 781
calculator/bin/calculator.apk , 65354
calculator/bin/classes/com/calculator/activity/CalculatorActivity.class , 4183
calculator/bin/classes/com/calculator/activity/R$attr.class , 355
calculator/bin/classes/com/calculator/activity/R$color.class , 499
calculator/bin/classes/com/calculator/activity/R$dimen.class , 411
calculator/bin/classes/com/calculator/activity/R$drawable.class , 553
calculator/bin/classes/com/calculator/activity/R$id.class , 955
calculator/bin/classes/com/calculator/activity/R$layout.class , 409
calculator/bin/classes/com/calculator/activity/R$string.class , 413
calculator/bin/classes/com/calculator/activity/R.class , 672
calculator/bin/classes.dex , 6496
calculator/bin/res/drawable-hdpi/calculator_blue.png , 13300
calculator/bin/res/drawable-hdpi/ic_launcher.png , 3966
calculator/bin/res/drawable-ldpi/ic_launcher.png , 1537
calculator/bin/res/drawable-mdpi/ic_launcher.png , 2200
calculator/bin/resources.ap_ , 59799
calculator/gen/com/calculator/activity/R.java , 2223
calculator/proguard.cfg , 1248
calculator/project.properties , 361
calculator/res/drawable/btn_select.xml , 367
calculator/res/drawable/white_bg.xml , 389
calculator/res/drawable-hdpi/bg.jpeg , 32649
calculator/res/drawable-hdpi/calculator_blue.png , 14084
calculator/res/drawable-hdpi/ic_launcher.png , 4147
calculator/res/drawable-ldpi/ic_launcher.png , 1723
calculator/res/drawable-mdpi/ic_launcher.png , 2574
calculator/res/layout/main.xml , 8432
calculator/res/values/colors.xml , 232
calculator/res/values/dimens.xml , 105
calculator/res/values/strings.xml , 117
calculator/src/com/calculator/activity/CalculatorActivity.java , 4840