Calculator App Added

So , This commit is regarding the calculator app I just made .. I developed this app to get familiar with linear layout and got to learn certain String methods in Kotlin..
Android dev. never makes me feel bored.

MyCalculator/.gitignore

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+*.iml
+.gradle
+/local.properties
+/.idea/caches
+/.idea/libraries
+/.idea/modules.xml
+/.idea/workspace.xml
+/.idea/navEditor.xml
+/.idea/assetWizardSettings.xml
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+.cxx
+local.properties

MyCalculator/app/.gitignore

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+/build

MyCalculator/app/build.gradle

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+plugins {
+    id 'com.android.application'
+    id 'kotlin-android'
+    id 'kotlin-android-extensions'
+}
+
+android {
+    compileSdkVersion 30
+    buildToolsVersion "30.0.3"
+
+    defaultConfig {
+        applicationId "com.example.mycalculator"
+        minSdkVersion 16
+        targetSdkVersion 30
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+}
+
+dependencies {
+
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    implementation 'androidx.core:core-ktx:1.6.0'
+    implementation 'androidx.appcompat:appcompat:1.3.1'
+    implementation 'com.google.android.material:material:1.4.0'
+    implementation 'androidx.constraintlayout:constraintlayout:2.1.0'
+    testImplementation 'junit:junit:4.+'
+    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
+}

MyCalculator/app/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

MyCalculator/app/src/androidTest/java/com/example/mycalculator/ExampleInstrumentedTest.kt

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+package com.example.mycalculator
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("com.example.mycalculator", appContext.packageName)
+    }
+}

MyCalculator/app/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.mycalculator">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.MyCalculator">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

MyCalculator/app/src/main/java/com/example/mycalculator/MainActivity.kt

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+package com.example.mycalculator
+
+import android.os.Bundle
+import android.view.View
+import android.widget.Button
+import androidx.appcompat.app.AppCompatActivity
+import kotlinx.android.synthetic.main.activity_main.*
+
+class MainActivity : AppCompatActivity() {
+
+    var lastNumeric : Boolean = false
+    var lastDot : Boolean = false
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+    }
+
+    fun onEqual(view: View){
+        if(lastNumeric){
+            var tvValue = tvInput.text.toString()
+            var prefix = ""
+            try{
+                if(tvValue.startsWith("-")){
+                    prefix = "-"
+                    tvValue = tvValue.substring(1)
+                }
+                if(tvValue.contains("-")){
+                    val splitValue = tvValue.split("-")
+
+                    var one = splitValue[0]
+                    var two = splitValue[1]
+
+                    if(!prefix.isEmpty()){
+                        one = prefix + one
+                    }
+                    tvInput.text = removeZeroAfterDot((one.toDouble() - two.toDouble()).toString())
+                }else if(tvValue.contains("/")){
+                    val splitValue = tvValue.split("/")
+
+                    var one = splitValue[0]
+                    var two = splitValue[1]
+
+                    if(!prefix.isEmpty()){
+                        one = prefix + one
+                    }
+                    tvInput.text = removeZeroAfterDot((one.toDouble() / two.toDouble()).toString())
+                }else if(tvValue.contains("+")){
+                    val splitValue = tvValue.split("+")
+
+                    var one = splitValue[0]
+                    var two = splitValue[1]
+
+                    if(!prefix.isEmpty()){
+                        one = prefix + one
+                    }
+                    tvInput.text = removeZeroAfterDot((one.toDouble()+two.toDouble()).toString())
+                }else if(tvValue.contains("X")){
+                    val splitValue = tvValue.split("X")
+
+                    var one = splitValue[0]
+                    var two = splitValue[1]
+
+                    if(!prefix.isEmpty()){
+                        one = prefix + one
+                    }
+                    tvInput.text = removeZeroAfterDot((one.toDouble() * two.toDouble()).toString())
+                }
+            }catch (e: ArithmeticException){
+                e.printStackTrace()
+            }
+        }
+    }
+
+    fun onDigit(view: android.view.View) {
+    tvInput.append((view as Button).text)
+        lastNumeric = true
+    }
+
+    private fun removeZeroAfterDot(result : String) : String{
+        var value =  result
+        if(result.contains(".0"))
+            value = result.substring(0 , result.length -2)
+        return value
+    }
+
+    fun onClear(view: View){
+        tvInput.text = ""
+        lastNumeric = false
+        lastDot = false
+    }
+
+    fun onDecimalPoint(view: View){
+        if(lastNumeric && !lastDot){
+            tvInput.append(".")
+            lastNumeric = false
+            lastDot = true
+        }
+    }
+
+    fun onOperator(view: View){
+        if(lastNumeric && !isOperatorAdded(tvInput.text.toString())){
+            tvInput.append((view as Button).text)
+            lastNumeric = false
+            lastDot = true
+        }
+    }
+
+    private fun isOperatorAdded(value : String) :Boolean {
+        return if(value.startsWith("-")){
+            false
+        }else{
+            value.contains("/") || value.contains("*") || value.contains("+") || value.contains("-")
+        }
+    }
+
+}

MyCalculator/app/src/main/res/drawable-v24/ic_launcher_foreground.xml

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+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path android:pathData="M31,63.928c0,0 6.4,-11 12.1,-13.1c7.2,-2.6 26,-1.4 26,-1.4l38.1,38.1L107,108.928l-32,-1L31,63.928z">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:endX="85.84757"
+                android:endY="92.4963"
+                android:startX="42.9492"
+                android:startY="49.59793"
+                android:type="linear">
+                <item
+                    android:color="#44000000"
+                    android:offset="0.0" />
+                <item
+                    android:color="#00000000"
+                    android:offset="1.0" />
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+        android:fillColor="#FFFFFF"
+        android:fillType="nonZero"
+        android:pathData="M65.3,45.828l3.8,-6.6c0.2,-0.4 0.1,-0.9 -0.3,-1.1c-0.4,-0.2 -0.9,-0.1 -1.1,0.3l-3.9,6.7c-6.3,-2.8 -13.4,-2.8 -19.7,0l-3.9,-6.7c-0.2,-0.4 -0.7,-0.5 -1.1,-0.3C38.8,38.328 38.7,38.828 38.9,39.228l3.8,6.6C36.2,49.428 31.7,56.028 31,63.928h46C76.3,56.028 71.8,49.428 65.3,45.828zM43.4,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2c-0.3,-0.7 -0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C45.3,56.528 44.5,57.328 43.4,57.328L43.4,57.328zM64.6,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2s-0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C66.5,56.528 65.6,57.328 64.6,57.328L64.6,57.328z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000" />
+</vector>