created a calculator blank

app/src/main/java/com/itis/androidlabproject/Calculator.kt

@@ -0,0 +1,31 @@
+package com.itis.androidlabproject
+
+import java.util.*
+
+open class Calculator(
+    var expression: String
+) {
+    private val Pi = 3.14
+    private val E = 2.71
+    private var expTree: TreeSet<Double>? = null
+
+    open fun calculate () {
+
+    }
+
+    private fun plus (a: Double, b: Double) : Double {
+        TODO()
+    }
+
+    private fun minus (a: Double, b: Double) : Double {
+        TODO()
+    }
+
+    private fun divide (a: Double, b: Double) : Double {
+        TODO()
+    }
+
+    private fun multiply (a: Double, b: Double) : Double {
+        TODO()
+    }
+}

app/src/main/java/com/itis/androidlabproject/Engineerable.kt

@@ -0,0 +1,7 @@
+package com.itis.androidlabproject
+
+interface Engineerable {
+    fun calcLog (a: Double, b: Double) : Double
+    fun sin(a: Double) : Double
+    fun cos(a: Double) : Double
+}

app/src/main/java/com/itis/androidlabproject/EngineeringCalculator.kt

@@ -0,0 +1,23 @@
+package com.itis.androidlabproject
+
+class EngineeringCalculator (
+    expression: String
+) : Calculator(expression), Engineerable {
+    override fun calculate () {
+
+    }
+
+    override fun calcLog(a: Double, b: Double): Double {
+        TODO("Not yet implemented")
+    }
+
+    override fun sin(a: Double): Double {
+        TODO("Not yet implemented")
+    }
+
+    override fun cos(a: Double): Double {
+        TODO("Not yet implemented")
+    }
+
+
+}

app/src/main/java/com/itis/androidlabproject/Graphable.kt

@@ -0,0 +1,5 @@
+package com.itis.androidlabproject
+
+interface Graphable {
+    fun buildGraph()
+}

app/src/main/java/com/itis/androidlabproject/GraphingCalculator.kt

@@ -0,0 +1,9 @@
+package com.itis.androidlabproject
+
+class GraphingCalculator(
+    expression: String
+) : Calculator(expression), Graphable {
+    override fun buildGraph() {
+        TODO("Not yet implemented")
+    }
+}

app/src/main/java/com/itis/androidlabproject/MainActivity.kt

@@ -7,5 +7,11 @@ class MainActivity : AppCompatActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
+
+        var simpleCalculator = Calculator("5.2+4")
+        var gCalculator = GraphingCalculator("y=5*x")
+        var engineeringCalculator = EngineeringCalculator("")
+
+        println(simpleCalculator.calculate())
     }
-}
+}