学校组织的《移动互联网应用软件开发》技能竞赛，所有参赛命题均基于 Android 4.2 版本实现，比赛推荐使用的开发环境为：ADT， JDK 1.6， Android SDK 4.1
经过了四天的培训我们小组选择在计算器应用
计算器能够实现：
目前我可以完成全部功能，虽然是扩展老师的基础程序，但还是很有成就感的。
我们先进行了对Java的培训，多线程、匿名内部类、接口及其子类异常的捕获，然后使用两本书《Android移动应用开发项目教程》和《Android编程权威指南》来开展对Android的学习。给我的感觉是，开发Android应用程序和普通的Java应用程序没有太大区别，最后运行的时候才Android虚拟机上运行就好。
开发Android项目的时候虽然老师给我们推荐谷歌推出了新的Android开发环境Android Studio，但是我们用的是带插件的Eclipse，安装好JDK配置好ADT集成开发环境之后就开始了。升级Android SDK也很重要，直接升级的话需要连接Google服务器的，所以是需要×××的，为了避免这种情况，也可以到高校自己的网站去升级。就不废话了，上代码。
MainActivity.java
package com.wangjingliang.calc;import java.util.*;import com.shiyifei.calc.R;import android.os.Bundle;import android.app.Activity;import android.util.Log;import android.view.Menu;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends Activity {
EditText result; // 保存当前输入框内容
String current = "0"; // 保存之前输入的内容
String prev = ""; // 保存输入状态，是刚刚输入了一个数字，还是输入了一个运算、控制符号
int status = 0; // 0 刚刚输入了数字， 1刚刚输入了运算符号
// 保存刚刚输入的运算符号
String com = ""; //保存存储器中的数值
String num = ""; @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); // 拿到输入框对象
result = (EditText) findViewById(R.id.editText1); // 让输入框一开始显示0
update();
} // 此处的方法是和在布局中给按钮们设定的onclick属性对应的
// 点完那些按钮后，执行该方法
public void click(View v) { // 现获取按钮上的内容
String btn_text = ((Button) v).getText().toString(); // 通过getId可以获取被点的按钮的id，和我们设定的id比照
switch (v.getId()) {
case R.id.b0:
case R.id.b1:
case R.id.b2:
case R.id.b3:
case R.id.b4:
case R.id.b5:
case R.id.b6:
case R.id.b7:
case R.id.b8:
case R.id.b9: // 检测上一次输入的是什么，如果是数字，就连接显示，如果是运算符，清空输入框，
// 开始新的数字的显示
if (status == 0) { // 检测当前输入框中是否仅有0，如果仅有零，就将当前内容替换为输入的数字
// 如果不是仅有0，则将当前按下的数字，连接到当前内容的最后
if (onlyZero())
current = btn_text; else
current += btn_text; // 把当前状态置为0，表示刚刚输入的是数字
status = 0;
} else if (status == 1) {
current = btn_text;
}
break; // 如果按下了加号
case R.id.b_add:
case R.id.b_sub:
case R.id.b_multi:
case R.id.b_div:
case R.id.b_sqrt:
case R.id.b_rev:
case R.id.b_per: // 把当前状态置为1，表示刚刚输入的是符号
status = 1; // 把当前输入框的内容，作为之前输入的内容保存在prev中
prev = current; // 保存当前运算符号
com = btn_text; break;
case R.id.b_equal:
compute();
break;
case R.id.b_c:
clearAll();
break;
case R.id.b_ce:
clearPart();
break;
case R.id.b_back:
clearSingle();
break;
case R.id.b_dot:
addDot();
break;
case R.id.b_sign:
addSign();
break;
case R.id.b_ms:
Store();
break;
case R.id.b_mr:
Out();
break;
case R.id.b_mp:
addStore();
break;
case R.id.b_mc:
clearIn();
break;
} // 更新输入框的当前内容
update();
} /**
* 按下等号后调用的方法，计算
*
* @return 返回计算结果
*/
private double compute() { double old = Double.parseDouble(prev); double cur = Double.parseDouble(current);
Log.d("------获取的按钮文字-------", com);
double result = 0;
if (com.equals("+")) {
result = old + cur;
} else if (com.equals("-")) {
result = old - cur;
} else if (com.equals("*")) {
result = old * cur;
} else if (com.equals("/")) { // 除数为0检测
if (cur == 0) {
warning();
} else {
result = old / cur;
}
} else if (com.equals("sqt")) {
result = Math.sqrt(old);
} else if (com.equals("1/x")) {
result = 1 / old;
} else if (com.equals("%")) {
cur = (old*cur) / 100;
} else if (com.equals("")) // 计算得到结果后，立刻更新输入框
prev = current;
current = result + "";
update(); return result;
} /**
* 清理之前和当前的数据
*/
private void clearAll() {
prev = "";
current = "";
com = "";
status = 0;
} private void clearPart() {
current = "";
} private void clearSingle() {
if (current.length() > 1) {
current = current.substring(0, current.length() - 1);
} else {
current = "0";
}
result.setText(current);
} private void Store() {
num = current ;
} private void addStore() {
double cur = Double.parseDouble(current);
double n = Double.parseDouble(num);
n += cur;
num = String.valueOf(n);
} private void Out() {
current = num ;
} private void clearIn() {
num = "";
} private void addDot() {
if (current.indexOf(".") != -1) {
current = "";
} else {
current = current + ".";
}
} private void addSign() {
if (current.indexOf("-") != -1) {
current = current.replace('-', ' ');
} else {
current = "-" + current;
}
} // 更新输入框内容
public void update() {
result.setText(current);
} public void warning() {
Toast.makeText(MainActivity.this, "除数不能为零", 0).show();
} /**
* 检测当前输入的内容是否仅仅是0
*
* @return 如果只有零，返回true，否则false
*/
public boolean onlyZero() {
return current.length() == 1 && current.equals("0");
}
}BuildConfig.Java
/** Automatically generated file. DO NOT MODIFY */
package com.shiyifei.calc;
public final class BuildConfig {
public final static boolean DEBUG = true;
}R.java
/* AUTO-GENERATED FILE. DO NOT MODIFY.
*
* This class was automatically generated by the
* aapt tool from the resource data it found. It
* should not be modified by hand.
*/package com.shiyifei.calc;public final class R {
public static final class attr {
} public static final class dimen {
/** Default screen margins, per the Android Design guidelines.
Customize dimensions originally defined in res/values/dimens.xml (such as
screen margins) for sw720dp devices (e.g. 10" tablets) in landscape here.
*/
public static final int activity_horizontal_margin=0x7f040000; public static final int activity_vertical_margin=0x7f040001;
} public static final class drawable {
public static final int ic_launcher=0x7f020000;
public static final int ic_launcher_calc=0x7f020001;
} public static final class id {
public static final int LinearLayout1=0x7f080000;
public static final int action_settings=0x7f080023; public static final int b0=0x7f08001e; public static final int b1=0x7f080017; public static final int b2=0x7f080018; public static final int b3=0x7f080019; public static final int b4=0x7f080010; public static final int b5=0x7f080011; public static final int b6=0x7f080012; public static final int b7=0x7f080009; public static final int b8=0x7f08000a; public static final int b9=0x7f08000b; public static final int b_add=0x7f080021; public static final int b_back=0x7f080004; public static final int b_c=0x7f080006; public static final int b_ce=0x7f080005; public static final int b_div=0x7f08000c; public static final int b_dot=0x7f080020; public static final int b_equal=0x7f080022;
public static final int b_mc=0x7f080008;
public static final int b_mp=0x7f08001d;
public static final int b_mr=0x7f08000f;
public static final int b_ms=0x7f080016;
public static final int b_multi=0x7f080013;
public static final int b_per=0x7f080014; public static final int b_rev=0x7f08001b; public static final int b_sign=0x7f08001f; public static final int b_sqrt=0x7f08000d; public static final int b_sub=0x7f08001a; public static final int editText1=0x7f080001; public static final int r1=0x7f080002; public static final int r2=0x7f080007; public static final int r3=0x7f08000e; public static final int r4=0x7f080015; public static final int r5=0x7f08001c; public static final int textView1=0x7f080003;
} public static final class layout {
public static final int activity_main=0x7f030000;
} public static final class menu {
public static final int main=0x7f070000;
} public static final class string {
public static final int action_settings=0x7f050001;
public static final int app_name=0x7f050000;
public static final int hello_world=0x7f050002;
} public static final class style {
/**
Base application theme, dependent on API level. This theme is replaced
by AppBaseTheme from res/values-vXX/styles.xml on newer devices.
Theme customizations available in newer API levels can go in
res/values-vXX/styles.xml, while customizations related to
backward-compatibility can go here.
Base application theme for API 11+. This theme completely replaces
AppBaseTheme from res/values/styles.xml on API 11+ devices.
API 11 theme customizations can go here.
Base application theme for API 14+. This theme completely replaces
AppBaseTheme from BOTH res/values/styles.xml and
res/values-v11/styles.xml on API 14+ devices.
API 14 theme customizations can go here.
*/
public static final int AppBaseTheme=0x7f060000;
/** Application theme.
All customizations that are NOT specific to a particular API-level can go here.
*/
public static final int AppTheme=0x7f060001;
}
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