1. 前言
這是我的第一個(gè)安卓app，從界面到算法都是自己寫(xiě)的，期間經(jīng)歷了各種各樣的bug凑队，也學(xué)到的各種各樣的知識(shí)，加深了對(duì)Java的使用幔翰，也了解了如何寫(xiě)一個(gè)Android應(yīng)用漩氨。因?yàn)槲襃ava也才入門(mén)，安卓更不用說(shuō)（第一行代碼第三章都沒(méi)看完）遗增，所以代碼寫(xiě)的肯定非常粗糙叫惊，望大家諒解。后期我會(huì)對(duì)其進(jìn)行改進(jìn)做修，也會(huì)上傳到此博客
2. 準(zhǔn)備
1. 編譯器：Android Studio
雖說(shuō)AndroidStudio有很多不如人意的地方（主要還是谷歌是一個(gè)404小公司）霍狰，特別是gradle。但是其作為現(xiàn)在谷歌力推的編譯器饰及，還是很值得信賴的蔗坯。基于Idea燎含，所以界面宾濒、插件等方面都不用說(shuō)，而且從Idea過(guò)來(lái)簡(jiǎn)直就是秒適應(yīng)（畢竟他就相當(dāng)于一個(gè)加強(qiáng)版Idea）屏箍。所以我個(gè)人推薦AndroidStudio绘梦。
2. 所需知識(shí)：
- 有一個(gè)簡(jiǎn)單的Java基礎(chǔ)橘忱。
我也就學(xué)到異常和泛型這塊，IO卸奉、多線程都沒(méi)學(xué) - 對(duì)Android開(kāi)發(fā)有一個(gè)簡(jiǎn)單的了解
我是看第一行代碼看到第三章基礎(chǔ)空間以及布局就開(kāi)始寫(xiě)了 - 對(duì)計(jì)算器算法的大致了解
中綴表達(dá)式轉(zhuǎn)后綴表達(dá)式钝诚，后綴表達(dá)式的運(yùn)算
3. 學(xué)會(huì)使用百度谷歌等搜索引擎
很多東西書(shū)上沒(méi)講，你不知道怎么實(shí)現(xiàn)榄棵，就直接百度或者google敲长，找到別人的博客，然后好好看一遍秉继，就算你看不懂祈噪，但是一定要看一遍，對(duì)其有一個(gè)大致的了解
4. 會(huì)使用AndroidStudio
至少懂得如何使用快捷鍵尚辑，懂得編譯器界面上各個(gè)部分干嘛的
3. 實(shí)現(xiàn)效果辑鲤，截圖
1. 實(shí)現(xiàn)效果
- 能實(shí)現(xiàn)表達(dá)式的運(yùn)算（廢話，好歹是個(gè)計(jì)算器）
- 當(dāng)你表達(dá)式存在問(wèn)題時(shí)杠茬，不讓你輸入月褥，或者不讓你按下等號(hào)，并且某些情況會(huì)提示你
- 能對(duì)負(fù)數(shù)進(jìn)行計(jì)算
- 有些簡(jiǎn)單的自動(dòng)補(bǔ)全功能
- 能拋出異常
2. 截圖
截圖.png
代碼部分
1. 界面
1. 使用百分比布局
我選擇的是百分比界面瓢喉，但是由于百分比布局是新增的布局宁赤，所以你得手動(dòng)添加其相應(yīng)的依賴
- 打開(kāi)
app/build.gradle文件，在dependencies閉包中添加這樣一行代碼
dependencies {
implementation 'com.android.support:percent:28.0.0-alpha3'
}
-
添加完畢后栓票，編輯面板頂部會(huì)出現(xiàn)一行提示决左，點(diǎn)擊Sync now稍等片刻即可
build提示.png
2. button周邊的邊框
因?yàn)锳ndroid對(duì)button不能通過(guò)設(shè)置屬性來(lái)達(dá)到顯示邊框的功能，所以我們只能創(chuàng)建一個(gè)圖片文件走贪，在圖片中設(shè)置背景色以及邊框的寬度和顏色佛猛，然后把button的background屬性設(shè)置為對(duì)應(yīng)圖片
- 首先在
app/src/main/res/drawable文件夾中新建一個(gè)Drawable resource file - 在彈出的窗口中設(shè)置文件名，文件名隨意坠狡，但是要簡(jiǎn)單易懂继找，而且編譯器不報(bào)錯(cuò)，例如我設(shè)置的
shape_blue_bg - 然后切換到text視圖逃沿，把代碼修改為
一定要把下面代碼中的注釋刪掉
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid
android:color="#f0ffff"/> //設(shè)置背景顏色婴渡，也就是你按鍵想要顯示的顏色
<stroke
android:width="0.01dp" //設(shè)置邊框的寬度
android:color="#ccc0c0c0"/> //設(shè)置邊框的顏色
</shape>
- 然后再在你的布局文件(例如
app/src/main/res/layout/activity_main.xml)中，對(duì)需要顯示邊框的button中添加設(shè)置背景這行代碼
一定要把下面代碼中的注釋刪掉
<Button
android:id="@+id/button0"
android:background="@drawable/click_white" //設(shè)置button的背景
/>
3. 實(shí)現(xiàn)button點(diǎn)擊變色功能
點(diǎn)擊變色.png
- 首先在
app/src/main/res/drawable文件夾中新建一個(gè)Drawable resource file凯亮，隨意起名碉纺，例如我的click_blue - 把代碼修改為
一定要把下面代碼中的注釋刪掉
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/shape_click_blue_bg" //設(shè)置背景尤蒿，就是上面的有邊框的文件馋评，你也可以就設(shè)置成顏色恨闪，或者其他圖片
android:state_enabled="true"
android:state_pressed="true"/> //當(dāng)button被點(diǎn)擊時(shí)
<item android:drawable="@drawable/shape_white_bg"http://設(shè)置背景，就是上面的有邊框的文件置谦，你也可以就設(shè)置成顏色堂鲤，或者其他圖片
android:state_enabled="true"
android:state_pressed="false"/> //當(dāng)button未被點(diǎn)擊時(shí)
</selector>
- 你可以看到他需要兩個(gè)drawable文件，一個(gè)是點(diǎn)擊時(shí)的顯示效果媒峡，一個(gè)是未點(diǎn)擊時(shí)的顯示效果瘟栖，而在設(shè)置邊框時(shí)還只創(chuàng)建了一個(gè)文件，也就是他不點(diǎn)擊時(shí)的文件谅阿，接下來(lái)半哟，我們還得創(chuàng)建一個(gè)跟他一樣的文件，只是顏色不同而已
- 創(chuàng)建一個(gè)邊框背景文件签餐，隨意命名
- 把代碼修改為如下
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#ffffff"/>
<stroke
android:width="0.01dp"
android:color="#ccc0c0c0"/>
</shape>
- 然后再在你的布局文件(例如
app/src/main/res/layout/activity_main.xml)中寓涨，對(duì)需要顯示邊框的button中添加設(shè)置背景這行代碼
一定要把下面代碼中的注釋刪掉
<Button
android:id="@+id/button0"
android:background="@drawable/click_blue" //設(shè)置button的背景，也就是你剛剛創(chuàng)建的那個(gè)起選擇按壓那個(gè)背景不按壓那個(gè)背景的文件
/>
4. 隱藏app默認(rèn)自帶標(biāo)題欄
- 在代碼中氯檐，在onCreate()中戒良，在super.onCreate(savedInstanceState)之后setContentView(R.layout.activity_main)之前添加
// 隱藏標(biāo)題欄
ActionBar actionBar = getSupportActionBar();
if (actionBar != null){
actionBar.hide();
}
5. 隱藏系統(tǒng)通知欄
- 在上面一樣的地方，添加
// 隱藏通知欄
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
6. 修改app名稱(chēng)
- 在
app/src/java/res/values/strings.xml文件中將第二行(一般默認(rèn)是第二行冠摄，不是第二行的話就在其他地方找糯崎，反正編輯器一定會(huì)自動(dòng)創(chuàng)建這行代碼的)
<resources>
<string name="app_name">小柯基的calculator</string> //“小柯基的calculator”就是我的app名稱(chēng)，你可以換成任何自己想要的名字
</resources>
7. 修改app圖標(biāo)
因?yàn)槠捏w我就不再這說(shuō)了河泳，分享博客地址
https://blog.csdn.net/zhangkaidsy/article/details/74852470
8. 將默認(rèn)字體修改為非襯線字體
由于默認(rèn)字體我覺(jué)得有點(diǎn)粗了沃呢，而網(wǎng)上的使用極細(xì)字體的方法又太細(xì)了，所以我就想到了修改字體的方法拆挥，還是在layout設(shè)置布局的xml文件中薄霜，找到你要修改字體的組件，添加一行android:typeface="sans"
<Button
android:id="@+id/button0"
android:text="@string/num0"
android:typeface="sans" //這行代碼就是修改
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
詳情見(jiàn)https://blog.csdn.net/l_lhc/article/details/51769245
9. 字體能適應(yīng)顯示框而改變大小
大家在很多app中都看到過(guò)一個(gè)功能纸兔，就是你輸入的文字黄锤，能隨著你輸入的文字的數(shù)量而快占滿顯示框的時(shí)候，自動(dòng)縮小字體以適應(yīng)顯示框
自動(dòng)適應(yīng).png
- 同樣是在顯示布局的文件中食拜，在顯示組件中添加一行代碼
<TextView
android:id="@+id/text_view"
app:autoSizeTextType="uniform" //開(kāi)啟字體自適應(yīng)功能
app:layout_heightPercent="25%"
app:layout_widthPercent="100%" />
- 但是這種方法存在一個(gè)問(wèn)題鸵熟，就是它自動(dòng)適應(yīng)輸入框大小，就是說(shuō)负甸，你的輸入框有多大流强，他顯示的字體就有多大，所以我們得對(duì)他做個(gè)限制呻待。限制最大字體和最小字體以及每次變化的字體的大小
<TextView
android:id="@+id/text_view"
app:autoSizeMaxTextSize="80sp" //最大字體
app:autoSizeMinTextSize="20sp" //最小字體
app:autoSizeStepGranularity="4sp" //每次變化的字體大小
app:autoSizeTextType="uniform" //開(kāi)啟字體自適應(yīng)功能
app:layout_heightPercent="25%"
app:layout_widthPercent="100%" />
10. 關(guān)于組件之間配色問(wèn)題
自己百度（手動(dòng)doge）
11. 代碼
layout/activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.percent.PercentRelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="@+id/buttonC"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:background="@drawable/click_yellow"
android:gravity="center"
android:text="@string/C"
android:textColor="#6f6f6f"
android:textSize="30sp"
android:typeface="sans"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/button0"
android:layout_width="81dp"
android:layout_height="81dp"
android:layout_alignParentBottom="true"
android:layout_toEndOf="@+id/buttonC"
android:background="@drawable/click_white"
android:gravity="center"
android:text="@string/num0"
android:typeface="sans"
android:textSize="30sp"
android:textColor="#6f6f6f"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/buttonDot"
android:layout_alignParentBottom="true"
android:layout_toEndOf="@id/button0"
android:background="@drawable/click_yellow"
android:gravity="center"
android:text="@string/Dot"
android:textSize="30sp"
android:textColor="#6f6f6f"
android:typeface="sans"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/buttonEqual"
android:layout_alignParentBottom="true"
android:layout_toEndOf="@id/buttonDot"
android:background="#58a6e3 "
android:gravity="center"
android:text="@string/equal"
android:textColor="#fff"
android:textSize="40sp"
android:typeface="sans"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/button1"
android:layout_above="@id/buttonC"
android:background="@drawable/click_white"
android:gravity="center"
android:text="@string/num1"
android:typeface="sans"
android:textColor="#6f6f6f"
android:textSize="30sp"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/button2"
android:layout_above="@id/button0"
android:layout_toEndOf="@id/button1"
android:background="@drawable/click_white"
android:gravity="center"
android:text="@string/num2"
android:textSize="30sp"
android:textColor="#6f6f6f"
android:typeface="sans"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/button3"
android:layout_above="@id/buttonDot"
android:layout_toEndOf="@id/button2"
android:background="@drawable/click_white"
android:gravity="center"
android:text="@string/num3"
android:textSize="30sp"
android:typeface="sans"
android:textColor="#6f6f6f"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/buttonAdd"
android:layout_above="@id/buttonEqual"
android:layout_toEndOf="@id/button3"
android:background="@drawable/click_blue_light"
android:gravity="center"
android:text="@string/add"
android:textColor="#019eff"
android:textSize="40sp"
android:typeface="sans"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/button4"
android:layout_above="@id/button1"
android:background="@drawable/click_white"
android:gravity="center"
android:text="@string/num4"
android:textSize="30sp"
android:typeface="sans"
android:textColor="#6f6f6f"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/button5"
android:layout_above="@id/button2"
android:layout_toEndOf="@id/button4"
android:background="@drawable/click_white"
android:gravity="center"
android:text="@string/num5"
android:textSize="30sp"
android:typeface="sans"
android:textColor="#6f6f6f"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/button6"
android:layout_above="@id/button3"
android:layout_toEndOf="@id/button5"
android:background="@drawable/click_white"
android:gravity="center"
android:text="@string/num6"
android:textSize="30sp"
android:typeface="sans"
android:textColor="#6f6f6f"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/buttonDec"
android:layout_above="@id/buttonAdd"
android:layout_toEndOf="@id/button6"
android:background="@drawable/click_blue_light"
android:gravity="center"
android:text="@string/dec"
android:textColor="#019eff"
android:textSize="40sp"
android:typeface="sans"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/button7"
android:layout_width="wrap_content"
android:layout_height="81dp"
android:layout_above="@id/button4"
android:background="@drawable/click_white"
android:gravity="center"
android:text="@string/num7"
android:textSize="30sp"
android:typeface="sans"
android:textColor="#6f6f6f"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/button8"
android:layout_width="81dp"
android:layout_height="81dp"
android:layout_above="@id/button5"
android:layout_marginStart="0dp"
android:layout_toEndOf="@id/button7"
android:background="@drawable/click_white"
android:gravity="center"
android:text="@string/num8"
android:textSize="30sp"
android:typeface="sans"
android:textColor="#6f6f6f"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/button9"
android:layout_above="@+id/button6"
android:layout_toEndOf="@id/button8"
android:background="@drawable/click_white"
android:gravity="center"
android:text="@string/num9"
android:textSize="30sp"
android:typeface="sans"
android:textColor="#6f6f6f"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/buttonMulti"
android:layout_above="@id/buttonDec"
android:layout_toEndOf="@id/button9"
android:background="@drawable/click_blue_light"
android:gravity="center"
android:text="@string/multi"
android:textColor="#019eff"
android:textSize="40sp"
android:typeface="sans"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/buttonAC"
android:layout_above="@+id/button7"
android:layout_alignParentStart="true"
android:background="@drawable/click_blue_light"
android:gravity="center"
android:text="@string/AC"
android:textSize="30sp"
android:textColor="#e47c5e"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/buttonBracketLeft"
android:layout_above="@id/button8"
android:layout_toEndOf="@id/buttonAC"
android:background="@drawable/click_blue_light"
android:gravity="center"
android:text="@string/BracketLeft"
android:textSize="30sp"
android:typeface="sans"
android:textColor="#019eff"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/buttonBracketRight"
android:layout_above="@id/button9"
android:layout_toEndOf="@id/buttonBracketLeft"
android:background="@drawable/click_blue_light"
android:gravity="center"
android:text="@string/BracketRight"
android:textSize="30sp"
android:textColor="#019eff"
android:typeface="sans"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<Button
android:id="@+id/buttonDiv"
android:layout_above="@id/buttonMulti"
android:layout_toEndOf="@id/buttonBracketRight"
android:background="@drawable/click_blue_light"
android:gravity="center"
android:text="@string/div"
android:textSize="30sp"
android:textColor="#019eff"
android:typeface="sans"
app:layout_heightPercent="15%"
app:layout_widthPercent="25%" />
<TextView
android:id="@+id/text_view"
android:background="#FAFFF0"
android:layout_alignParentTop="true"
android:gravity="end|center_vertical"
app:autoSizeMaxTextSize="80sp"
app:autoSizeMinTextSize="20sp"
app:autoSizeStepGranularity="4sp"
app:autoSizeTextType="uniform"
app:layout_heightPercent="25%"
app:layout_widthPercent="100%" />
</android.support.percent.PercentRelativeLayout>
values/strings.xml
<resources>
<string name="app_name">小柯基的calculator</string>
<string name="AC">AC</string>
<string name="AddDec">+/-</string>
<string name="equal">=</string>
<string name="add">+</string>
<string name="dec">-</string>
<string name="multi">*</string>
<string name="div">/</string>
<string name="Dot">.</string>
<string name="num0">0</string>
<string name="num1">1</string>
<string name="num2">2</string>
<string name="num3">3</string>
<string name="num4">4</string>
<string name="num5">5</string>
<string name="num6">6</string>
<string name="num7">7</string>
<string name="num8">8</string>
<string name="num9">9</string>
<string name="BracketLeft">(</string>
<string name="BracketRight">)</string>
<string name="Mod">%</string>
<string name="Delete">刪除</string>
<string name="C">C</string>
</resources>
values/styles.xml
<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">@color/colorPrimary</item>
<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
<item name="colorAccent">@color/colorAccent</item>
</style>
<style name="baseTextStyle">
<item name="android:layout_width">wrap_content</item>
<item name="android:layout_height">wrap_content</item>
<item name="android:fontFamily">sans-serif-light</item>
</style>
</resources>
drawable/click_blue.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/shape_click_blue_bg" android:state_enabled="true"
android:state_pressed="true"/>
<item android:drawable="@drawable/shape_white_bg" android:state_enabled="true"
android:state_pressed="false"/>
</selector>
drawable/click_blue_light.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/shape_white_bg" android:state_enabled="true"
android:state_pressed="true"/>
<item android:drawable="@drawable/shape_click_blue_bg" android:state_enabled="true"
android:state_pressed="false"/>\
</selector>
drawable/click_white.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/shape_click_blue_bg" android:state_enabled="true"
android:state_pressed="true"/>
<item android:drawable="@drawable/shape_white_bg" android:state_enabled="true"
android:state_pressed="false"/>\
</selector>
drawable/click_yellow.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/shape_white_bg" android:state_enabled="true"
android:state_pressed="true"/>
<item android:drawable="@drawable/shape_yellow_bg" android:state_enabled="true"
android:state_pressed="false"/>\
</selector>
drawable/shape_click_blue_bg.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid
android:color="#f0ffff"/>
<stroke
android:width="0.01dp"
android:color="#ccc0c0c0"/>
</shape>
drawable/shape_white_bg.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#ffffff"/>
<stroke
android:width="0.01dp"
android:color="#ccc0c0c0"/>
</shape>
drawable/shape_yellow_bg.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid
android:color="#c8fffaf0"/>
<stroke
android:width="0.01dp"
android:color="#ccc0c0c0"/>
</shape>
活動(dòng)的代碼
1. 異常處理
- 當(dāng)輸出的結(jié)果有問(wèn)題時(shí)打月，拋出異常，然后顯示Error
- 當(dāng)左括號(hào)數(shù)目等于或者小于右括號(hào)時(shí)蚕捉，不然輸入右括號(hào)奏篙，而且按等號(hào)不會(huì)運(yùn)算，提示括號(hào)不匹配
- 當(dāng)前面是符號(hào)，然后輸入減號(hào)默認(rèn)添加'('當(dāng)負(fù)號(hào)處理
- 實(shí)現(xiàn)輸入是'數(shù)字（數(shù)字'時(shí)秘通，當(dāng)乘法處理
···還有很多功能就不一一列舉了
2. 點(diǎn)擊時(shí)手機(jī)震動(dòng)
- 首先在AndroidManifest.xml中添加震動(dòng)權(quán)限
<uses-permission android:name="android.permission.VIBRATE" />
- 新建class文件为严，命名為
Vibrate
代碼如下
package com.example.calculator;
import android.content.Context;
import android.os.Vibrator;
/**
* Created by littlecorgi_a1203991686 on 2018/08/02 15:56.
*/
public class Vibrate {
private static Vibrator vibrator;
/**
* 簡(jiǎn)單震動(dòng)
* @param context 調(diào)用震動(dòng)的Context
* @param millisecond 震動(dòng)的時(shí)間，毫秒
*/
@SuppressWarnings("static-access")
public static void vSimple(Context context, int millisecond) {
vibrator = (Vibrator) context.getSystemService(context.VIBRATOR_SERVICE);
vibrator.vibrate(millisecond);
}
/**
* 停止震動(dòng)
*/
public static void stop() {
if (vibrator != null) {
vibrator.cancel();
}
}
}
3. MainActivity代碼
package com.example.calculator;
import android.annotation.SuppressLint;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private TextView textview;
private StringBuilder sb = new StringBuilder();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// 隱藏標(biāo)題欄
ActionBar actionBar = getSupportActionBar();
if (actionBar != null){
actionBar.hide();
}
// 隱藏通知欄
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
// 定義控件
Button button0 = findViewById(R.id.button0);
Button button1 = findViewById(R.id.button1);
Button button2 = findViewById(R.id.button2);
Button button3 = findViewById(R.id.button3);
Button button4 = findViewById(R.id.button4);
Button button5 = findViewById(R.id.button5);
Button button6 = findViewById(R.id.button6);
Button button7 = findViewById(R.id.button7);
Button button8 = findViewById(R.id.button8);
Button button9 = findViewById(R.id.button9);
Button buttonC = findViewById(R.id.buttonC);
Button buttonDot = findViewById(R.id.buttonDot);
Button buttonEqual = findViewById(R.id.buttonEqual);
Button buttonAdd = findViewById(R.id.buttonAdd);
Button buttonDec = findViewById(R.id.buttonDec);
Button buttonMulti = findViewById(R.id.buttonMulti);
Button buttonAC = findViewById(R.id.buttonAC);
Button buttonBracketLeft = findViewById(R.id.buttonBracketLeft);
Button buttonBracketRight = findViewById(R.id.buttonBracketRight);
Button buttonDiv = findViewById(R.id.buttonDiv);
textview = findViewById(R.id.text_view);
button0.setOnClickListener(this);
button1.setOnClickListener(this);
button2.setOnClickListener(this);
button3.setOnClickListener(this);
button4.setOnClickListener(this);
button5.setOnClickListener(this);
button6.setOnClickListener(this);
button7.setOnClickListener(this);
button8.setOnClickListener(this);
button9.setOnClickListener(this);
buttonAC.setOnClickListener(this);
buttonAdd.setOnClickListener(this);
buttonBracketLeft.setOnClickListener(this);
buttonBracketRight.setOnClickListener(this);
buttonC.setOnClickListener(this);
buttonDec.setOnClickListener(this);
buttonDiv.setOnClickListener(this);
buttonDot.setOnClickListener(this);
buttonEqual.setOnClickListener(this);
buttonMulti.setOnClickListener(this);
}
private int count_negative = 0; //負(fù)數(shù)標(biāo)記
private final int vibrate_time = 5; //震動(dòng)時(shí)長(zhǎng)
private boolean equals = false;
private int count_bracket_left = 0;
private int count_bracket_right = 0;
@SuppressLint("SetTextI18n")
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.button0:
if (equals) {
sb = sb.delete(0, sb.length());
equals = false;
}
sb = sb.append("0");
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.button1:
if (equals) { //當(dāng)equals為true肺稀，輸入數(shù)字第股，清空字符串，在把標(biāo)志變?yōu)閒alse
sb = sb.delete(0, sb.length());
equals = false;
}
if (sb.length() > 0 && sb.charAt(sb.length() - 1) == ')') {
sb = sb.append("*1");
} else {
sb = sb.append("1");
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.button2:
if (equals) {
sb = sb.delete(0, sb.length());
equals = false;
}
if (sb.length() > 0 && sb.charAt(sb.length() - 1) == ')') {
sb = sb.append("*2");
} else {
sb = sb.append("2");
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.button3:
if (equals) {
sb = sb.delete(0, sb.length());
equals = false;
}
if (sb.length() > 0 && sb.charAt(sb.length() - 1) == ')') {
sb = sb.append("*3");
} else {
sb = sb.append("3");
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.button4:
if (equals) {
sb = sb.delete(0, sb.length());
equals = false;
}
if (sb.length() > 0 && sb.charAt(sb.length() - 1) == ')') {
sb = sb.append("*4");
} else {
sb = sb.append("4");
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.button5:
if (equals) {
sb = sb.delete(0, sb.length());
equals = false;
}
if (sb.length() > 0 && sb.charAt(sb.length() - 1) == ')') {
sb = sb.append("*5");
} else {
sb = sb.append("5");
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.button6:
if (equals) {
sb = sb.delete(0, sb.length());
equals = false;
}
if (sb.length() > 0 && sb.charAt(sb.length() - 1) == ')') {
sb = sb.append("*6");
} else {
sb = sb.append("6");
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.button7:
if (equals) {
sb = sb.delete(0, sb.length());
equals = false;
}
if (sb.length() > 0 && sb.charAt(sb.length() - 1) == ')') {
sb = sb.append("*7");
} else {
sb = sb.append("7");
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.button8:
if (equals) {
sb = sb.delete(0, sb.length());
equals = false;
}
if (sb.length() > 0 && sb.charAt(sb.length() - 1) == ')') {
sb = sb.append("*8");
} else {
sb = sb.append("8");
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.button9:
if (equals) {
sb = sb.delete(0, sb.length());
equals = false;
}
if (sb.length() > 0 && sb.charAt(sb.length() - 1) == ')') {
sb = sb.append("*9");
} else {
sb = sb.append("9");
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.buttonC: //刪除
if (equals) {
equals = false;
}
if (sb.length() != 0) {
sb = sb.deleteCharAt(sb.length() - 1);
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.buttonAC: //清空
if (equals) {
equals = false;
}
sb = sb.delete(0, sb.length());
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.buttonBracketLeft: //左括號(hào)
if (equals) {
equals = false;
}
if (sb.length() > 0 && (sb.charAt(sb.length() - 1) >= '0' && sb.charAt(sb.length() - 1) <= '9')) { //當(dāng)前面是數(shù)字是话原，自動(dòng)添加為'*('
sb = sb.append("*(");
}
if (sb.length() == 0) { //如果此時(shí)字符串是空的夕吻，也就是說(shuō)想在式子最前面添加括號(hào)，就添加括號(hào)
sb = sb.append("(");
}
if (sb.length() > 0 && (sb.charAt(sb.length() - 1) == '*' || sb.charAt(sb.length() - 1) == '/' || sb.charAt(sb.length() - 1) == '+' || sb.charAt(sb.length() - 1) == '-')) { //如果當(dāng)括號(hào)前面是符號(hào)時(shí)添加括號(hào)
sb = sb.append("(");
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.buttonBracketRight: //=右括號(hào)
if (equals) {
equals = false;
}
int count_num = 0; //數(shù)字的數(shù)目
count_bracket_left = count_bracket_right = 0;
if (sb.length() != 0) {
for (int i = sb.length() - 1; i >= 0; i--) { //對(duì)字符串進(jìn)行遍歷繁仁，如果存在左括號(hào)且括號(hào)中有數(shù)字涉馅，標(biāo)記轉(zhuǎn)為真,
if (count_bracket_left == 0 && (sb.charAt(i) >= '0' && sb.charAt(i) <= '9')) {
count_num++;
}
if (sb.charAt(i) == '(') {
count_bracket_left++;
}
if (sb.charAt(i) == ')') {
count_bracket_right++;
}
}
Log.d("count_bracket", String.valueOf(count_bracket_left+" "+count_bracket_right));
if ((count_bracket_left > count_bracket_right) && count_num > 0) { //當(dāng)標(biāo)記均為真，也就是存在左括號(hào)時(shí)且在左括號(hào)前面有數(shù)字黄虱，才讓添加括號(hào)
sb = sb.append(")");
}
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.buttonDiv: //除號(hào)
if (equals) {
equals = false;
}
if (sb.length() != 0) {
if ((sb.charAt(sb.length() - 1) >= '0' && sb.charAt(sb.length() - 1) <= '9') || sb.charAt(sb.length() - 1) == '.') {
if ((sb.charAt(sb.length() - 1) >= '0' && sb.charAt(sb.length() - 1) <= '9')) { //如果前一位是數(shù)字稚矿，就直接添加
// if (count_negative > 0){ //如果前面是負(fù)數(shù)，就加上括號(hào)
// sb = sb.append(")/");
// count_negative = 0;
// } else {
sb = sb.append("/");
// }
}
if (sb.charAt(sb.length() - 1) == '.') { //如果前一位是'.',就先為前一位數(shù)字補(bǔ)0
sb = sb.append("0/");
}
}
if ((sb.charAt(sb.length() - 1) == ')')) { //如果前一位是')'也讓加上/
sb = sb.append("/");
}
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.buttonMulti: //乘號(hào)
if (equals) {
equals = false;
}
if (sb.length() != 0) {
if ((sb.charAt(sb.length() - 1) >= '0' && sb.charAt(sb.length() - 1) <= '9') || sb.charAt(sb.length() - 1) == '.') {
if ((sb.charAt(sb.length() - 1) >= '0' && sb.charAt(sb.length() - 1) <= '9')) {//如果前一位是數(shù)字悬钳，就直接添加
sb = sb.append("*");
}
if (sb.charAt(sb.length() - 1) == '.') {//如果前一位是'.',就先為前一位數(shù)字補(bǔ)0
sb = sb.append("0*");
}
}
if ((sb.charAt(sb.length() - 1) == ')')) {
sb = sb.append("*");
}
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.buttonDec: //減號(hào)
if (equals) {
equals = false;
}
if (sb.length() != 0) {
if ((sb.charAt(sb.length() - 1) >= '0' && sb.charAt(sb.length() - 1) <= '9') || sb.charAt(sb.length() - 1) == '.' ||
sb.charAt(sb.length() - 1) == '(') {
if (sb.charAt(sb.length() - 1) >= '0' && sb.charAt(sb.length() - 1) <= '9') {//如果前一位是數(shù)字盐捷，就直接添加
// if (count_negative > 0) { //如果前面是負(fù)數(shù)，就加上括號(hào)
// sb = sb.append(")-");
// count_negative = 0;
// } else {
sb = sb.append("-");
// }
}
if (sb.charAt(sb.length() - 1) == '.') {//如果前一位是'.',就先為前一位數(shù)字補(bǔ)0
sb = sb.append("0-");
}
if (sb.charAt(sb.length() - 1) == '(') {
sb = sb.append("-");
count_negative++;
}
} else if ((sb.charAt(sb.length() - 1) == ')')) {
sb = sb.append("-");
} else {
sb = sb.append("(-");
}
} else { //負(fù)號(hào)
sb = sb.append("(-");
count_negative++;
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.buttonAdd: //加號(hào)
if (equals) {
equals = false;
}
if (sb.length() != 0) {
if ((sb.charAt(sb.length() - 1) >= '0' && sb.charAt(sb.length() - 1) <= '9') || sb.charAt(sb.length() - 1) == '.') {
if ((sb.charAt(sb.length() - 1) >= '0' && sb.charAt(sb.length() - 1) <= '9')) {//如果前一位是數(shù)字默勾，就直接添加
// if (count_negative > 0) { //如果前面是負(fù)數(shù)碉渡，就加上括號(hào)
// sb = sb.append(")+");
// count_negative = 0;
// } else {
sb = sb.append("+");
// }
}
if (sb.charAt(sb.length() - 1) == '.') {//如果前一位是'.',就先為前一位數(shù)字補(bǔ)0
sb = sb.append("0+");
}
}
if ((sb.charAt(sb.length() - 1) == ')')) {
sb = sb.append("+");
}
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.buttonDot: //小數(shù)點(diǎn)
if (equals) {
equals = false;
}
if (sb.length() != 0) {
int count_dot = 0;
for (int i = sb.length() - 1; i >= 0; i--) {
if (sb.charAt(i) == '.') {
count_dot++;
}
if (!(sb.charAt(i) >= '0' && sb.charAt(i) <= '9')) {
break;
}
}
if (count_dot == 0) {
if (sb.charAt(sb.length() - 1) == '*' || sb.charAt(sb.length() - 1) == '/' || sb.charAt(sb.length() - 1) == '+' || sb.charAt(sb.length() - 1) == '-') {
// 如果最后一位是符號(hào)時(shí)，直接輸小數(shù)點(diǎn)會(huì)自動(dòng)補(bǔ)'0'母剥，形成'0.'
sb = sb.append("0.");
} else {
sb = sb.append(".");
}
}
}
Vibrate.vSimple(view.getContext(), vibrate_time);
textview.setText(sb.toString());
break;
case R.id.buttonEqual: //等號(hào)
if (equals) {
equals = false;
}
count_bracket_right = count_bracket_left = 0;
if (sb.length() != 0) {
for (int i = 0; i < sb.length(); i++) {
if (sb.charAt(i) == '(')
count_bracket_left++;
if (sb.charAt(i) == ')')
count_bracket_right++;
}
if (count_bracket_left != count_bracket_right) {
Toast.makeText(MainActivity.this, "請(qǐng)注意括號(hào)匹配", Toast.LENGTH_SHORT).show();
}
if (count_bracket_left == count_bracket_right &&
((sb.charAt(sb.length() - 1) >= '0' && sb.charAt(sb.length() - 1) <= '9') || sb.charAt(sb.length() - 1) == ')')) {
equals = true;
count_negative = 0;
try {
textview.setText(InfixToSufix.Cal(InfixToSufix.Suffix(sb)));
sb = sb.delete(0, sb.length());
sb.append(textview.getText().toString());
} catch (Exception e){
textview.setText("Error");
sb = sb.delete(0, sb.length());
}
}
}
Vibrate.vSimple(view.getContext(), vibrate_time);
break;
default:
break;
}
}
}
算法
1. 中綴表達(dá)式轉(zhuǎn)后綴表達(dá)式
http://www.nowamagic.net/librarys/veda/detail/2307
2. 后綴表達(dá)式的計(jì)算
http://www.nowamagic.net/librarys/veda/detail/2306
3. 具體代碼
在MainActivity同一個(gè)包下新建class文件滞诺，命名為InfixToSuffix
代碼如下
package com.example.calculator;
import android.util.Log;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Stack;
/**
* Created by littlecorgi_a1203991686 on 2018/08/02 15:56.
*/
public class InfixToSuffix {
/**
* 中綴轉(zhuǎn)后綴
* @param str 從鍵盤(pán)讀入的String類(lèi)型的對(duì)象，也就是要求的表達(dá)式
* @return 返回一個(gè)ArrayList類(lèi)型的對(duì)象环疼，也就是一個(gè)集合习霹，也即是后綴表達(dá)式，讓cal方法接收炫隶，
*/
public static ArrayList Suffix(StringBuilder str){
/*
* Stack() 構(gòu)造方法
* void add(int index, Object element) 在此向量的指定位置插入指定的元素
* boolean empty() 測(cè)試堆棧是否為空
* Object pop( ) 移除堆棧頂部的對(duì)象淋叶，并作為此函數(shù)的值返回該對(duì)象
* Object push(Object element) 把項(xiàng)壓入堆棧頂部
*/
for (int i = 1; i < str.length(); i++){ //識(shí)別到'(-'自動(dòng)補(bǔ)0
if (str.charAt(i) == '-' && str.charAt(i - 1) == '('){
str.insert(i, '0');
}
}
StringBuilder temp = new StringBuilder(); // 當(dāng)做中間字符串，臨時(shí)存放數(shù)字伪阶，方便往list中添加
List<String> list = new ArrayList<>(); // 用于存儲(chǔ)分割后的數(shù)字和符號(hào)
ArrayList<String> result = new ArrayList<>(); //作為結(jié)果集合煞檩，后綴表達(dá)式保存在其中
for (int i = 0; i < str.length(); i++){
// if ( i != str.length() - 1 ){ //對(duì)不是最后一位數(shù)字的
if ((str.charAt(i) >= '0' && str.charAt(i) <= '9') || str.charAt(i) == '.'){ // 判斷是不是數(shù)字
if (str.charAt(i) == '.' && temp.length() == 0){ //如果此位為'.'，且這個(gè)時(shí)候中間字符串為空栅贴，自動(dòng)補(bǔ)0
temp.append(0); // 添加0斟湃，在添加'.'
temp.append(str.charAt(i));
} else {
temp.append(str.charAt(i)); // 是數(shù)字，就往中間字符串添加
}
if (i == str.length() - 1){ //對(duì)最后一位進(jìn)行單獨(dú)判斷檐薯，如果是字符串最后一位凝赛，直接進(jìn)行添加到list操作
list.add(temp.toString());
}
} else { // 不是數(shù)字
if (temp.length() != 0)
list.add(temp.toString()); // 判斷中間字符串長(zhǎng)度是不是0，不是0就往list中添加
list.add(String.valueOf(str.charAt(i))); // 將符號(hào)往list中添加
temp.delete(0, temp.length()); // 清空中間字符串
}
// } else { //單獨(dú)把最后一個(gè)字符拿出來(lái)進(jìn)行判斷
// if ((str.charAt(i) >= '0' && str.charAt(i) <= '9') || str.charAt(i) == '.'){ // 下面代碼注釋參考上面
// temp.append(str.charAt(i));
//
// } else {
// if (temp.length() != 0)
// list.add(temp.toString()); // 判斷中間字符串長(zhǎng)度是不是0，不是0就往list中添加
// list.add(String.valueOf(str.charAt(i)));
// temp.delete(0, temp.length());
// }
// }
}
// 遍歷輸出
for (String aList : list) {
System.out.print(aList + " ");
}
System.out.println();
// 定義棧
Stack<String> stack = new Stack<>();
// 定義符號(hào)的優(yōu)先級(jí)
Map<Character, Integer> map = new HashMap<>();
map.put('(', 0);
map.put(')', 0);
map.put('*', 1);
map.put('/', 1);
map.put('+', 2);
map.put('-', 2);
for ( String s : list ) {
// System.out.println("s=" + s);
if ( s.equals("*") || s.equals("/") || s.equals("+") || s.equals("-") || s.equals("(") || s.equals(")") ){ //不為數(shù)字
if (stack.size() == 0){ //如果當(dāng)前棧里面沒(méi)有元素墓猎，不管是啥捆昏，直接進(jìn)棧
stack.push(s);
} else { //如果棧中有元素
if (s.equals(")")) { //如果當(dāng)前是),那就的往前找(與其對(duì)應(yīng)輸出
if (!stack.empty()){ //容錯(cuò)，不然會(huì)有EmptyStackException陶衅，下面的類(lèi)似的表達(dá)式同理
while (!stack.peek().equals("(")){ //循環(huán)屡立，從棧頂開(kāi)始循環(huán)直晨，一直到棧頂為(搀军，退出循環(huán)
// System.out.print(stack.pop() + " "); //輸出并且把棧頂元素移除
result.add(stack.pop()); //保存到結(jié)果集合中，并且把棧頂元素移除
if (stack.empty()){//容錯(cuò)勇皇，不然會(huì)有EmptyStackException,見(jiàn)上面
break;
}
}
if (!stack.empty()){
if (stack.peek().equals("("))//如果此時(shí)棧頂元素為(,就將他移除罩句，原因是后綴表達(dá)式不用(，而在之前我們將他壓入了棧中,具體見(jiàn)下面第5行
stack.pop();
}
}
} else{
if (s.equals("(")){ //如果是'('將其入棧
stack.push(s);
} else {
if (stack.peek().charAt(0) != '('){
if ( map.get(s.charAt(0)) < map.get(stack.peek().charAt(0)) ){ //棧頂符號(hào)的優(yōu)先級(jí)高于元素優(yōu)先級(jí)敛摘，也就是數(shù)字小门烂，進(jìn)棧
stack.push(s);
} else { //棧頂符號(hào)優(yōu)先級(jí)低于元素優(yōu)先級(jí)，輸出并循環(huán)
while ((map.get(s.charAt(0)) >= map.get(stack.peek().charAt(0))) && !stack.empty()){
// System.out.print(stack.pop() + " ");
result.add(stack.pop());
if (stack.empty()){
break;
}
if (stack.peek().equals("(")){
break;
}
}
stack.push(s);
}
} else {
stack.push(s);
}
}
}
}
} else { //是數(shù)字
result.add(s);
}
}
while (!stack.empty()){ //最后遍歷棧兄淫，把結(jié)果保存到result中屯远，直到棧被清空
result.add(stack.pop());
}
return result;
}
/**
* 用于計(jì)算后綴表達(dá)式的結(jié)果
* @param arrayList 從Suffix傳出來(lái)的后綴表達(dá)式
* @return 返回String類(lèi)型對(duì)象，也就是最后的結(jié)果
*/
public static String Cal(ArrayList arrayList){
int length = arrayList.size();
String[] arr = new String[length]; //轉(zhuǎn)為字符串?dāng)?shù)組,方便模擬棧
for (int i = 0; i < arrayList.size(); i++){
arr[i] = (String)arrayList.get(i);
}
Log.d("asdfg", arrayList.toString());
List<String> list = new ArrayList<>();
for (String anArr : arr) { //此處就是上面說(shuō)的運(yùn)算過(guò)程捕虽，因?yàn)閘ist.remove的緣故慨丐，所以取出最后一個(gè)數(shù)個(gè)最后兩個(gè)數(shù) 都是size-2
int size = list.size();
switch (anArr) {
case "+":
BigDecimal a = new BigDecimal(list.remove(size - 2)).add(new BigDecimal(list.remove(size - 2)));
// list.add(String.valueOf(a.stripTrailingZeros().toPlainString()));
list.add(a.stripTrailingZeros().toString()); //去掉結(jié)果最后的0
break;
case "-":
BigDecimal b = new BigDecimal(list.remove(size - 2)).subtract(new BigDecimal(list.remove(size - 2)));
list.add(b.stripTrailingZeros().toString());
break;
case "*":
BigDecimal c = new BigDecimal(list.remove(size - 2)).multiply(new BigDecimal(list.remove(size - 2)));
list.add(c.stripTrailingZeros().toString());
break;
case "/":
BigDecimal d = new BigDecimal(list.remove(size - 2)).divide(new BigDecimal(list.remove(size - 2)), 10, BigDecimal.ROUND_HALF_UP);
list.add(d.stripTrailingZeros().toString());
break;
default:
list.add(anArr);
break;//如果是數(shù)字 直接放進(jìn)list中
}
}
if (list.size() == 1){
if (list.get(0).length() < 30){ //當(dāng)結(jié)果長(zhǎng)度不長(zhǎng)時(shí)，就直接輸出
BigDecimal bd = new BigDecimal(list.get(0));
return bd.toPlainString(); //BigDecimal默認(rèn)直接輸出
} else { //當(dāng)結(jié)果過(guò)長(zhǎng)時(shí)泄私，就用科學(xué)計(jì)數(shù)法輸出
double d = Double.valueOf(list.get(0));
return String.valueOf(d); //Double會(huì)使用科學(xué)計(jì)數(shù)法輸出
}
} else {
return "運(yùn)算失敗";
}
}
}
