Added task removal, task saving/loading

- Also refactored/moved around code for better viewing/functionality

app/build.gradle

@@ -31,6 +31,7 @@ dependencies {
     implementation 'androidx.appcompat:appcompat:1.3.1'
     implementation 'androidx.constraintlayout:constraintlayout:2.1.0'
     implementation 'androidx.recyclerview:recyclerview:1.2.1'
+    implementation 'commons-io:commons-io:2.6'
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'androidx.test.ext:junit:1.1.3'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'

app/src/main/java/com/embers/simpleto_do/MainActivity.kt

@@ -1,6 +1,7 @@
 package com.embers.simpleto_do
 
 import android.os.Bundle
+import android.util.Log
 import android.view.KeyEvent
 import android.view.View
 import android.widget.Button
@@ -8,30 +9,88 @@ import android.widget.EditText
 import androidx.appcompat.app.AppCompatActivity
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
+import org.apache.commons.io.FileUtils
+import java.io.File
+import java.io.IOException
+import java.nio.charset.Charset
 
 class MainActivity : AppCompatActivity() {
-    private val taskList = mutableListOf<String>()
+    private val TAG: String = this::class.java.name
+
+    private var taskList = mutableListOf<String>()
+    private lateinit var editText: EditText
+    private lateinit var recyclerView: RecyclerView
+    private lateinit var adapter : TaskItemAdapter
+    private lateinit var button: Button
+
+    private fun getDataFile() : File {
+        return File(filesDir, "data.txt")
+    }
+
+    private fun saveData(data: List<String> = taskList) {
+        val file: File = getDataFile()
+        try {
+            FileUtils.writeLines(file, data)
+            Log.i(TAG, "Successfully wrote ${taskList.size} tasks to ${file.absolutePath}")
+        } catch (exception: IOException) {
+            exception.printStackTrace()
+        }
+    }
+
+    /**
+     * Load data from the relevant data file.
+     *
+     */
+    private fun loadData() {
+        val file: File = getDataFile()
+        try {
+            taskList = FileUtils.readLines(file, Charset.defaultCharset())
+            Log.i(TAG, "Successfully read ${taskList.size} tasks from ${file.absolutePath}")
+        } catch (exception: IOException) {
+            exception.printStackTrace()
+        }
+    }
+
+    /**
+     * Updates the enabled state of the 'Add' button depending on whether the text field has text.
+     *
+     */
+    private fun refreshButton() {
+        button.isEnabled = editText.text.isNotBlank()
+    }
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
 
-        // Button is by default disabled (no text in textbox)
-        val button = findViewById<Button>(R.id.button)
-        button.isEnabled = false
+        loadData()
+
+        /**
+         * Callback to remove a task at a given location in the list (on long click action)
+         */
+        val onLongClickListener = object : TaskItemAdapter.OnLongClickListener {
+            override fun onItemLongClicked(position: Int) {
+                taskList.removeAt(position)
+                adapter.notifyItemRemoved(position)
+                saveData()
+            }
+        }
 
         // Setup RecyclerView
-        val editText = findViewById<EditText>(R.id.editTodoText)
-        val recyclerView = findViewById<RecyclerView>(R.id.recyclerView)
-        val adapter = TaskItemAdapter(taskList)
+        editText = findViewById<EditText>(R.id.editTodoText)
+        recyclerView = findViewById<RecyclerView>(R.id.recyclerView)
+        adapter = TaskItemAdapter(taskList, onLongClickListener)
         recyclerView.adapter = adapter
         recyclerView.layoutManager = LinearLayoutManager(this)
+        button = findViewById(R.id.button)
+
+        refreshButton()
 
         // Disable add task button when text is not inside EditText
         findViewById<EditText>(R.id.editTodoText).setOnKeyListener(View.OnKeyListener { v, keyCode, event ->
             // Read only event after the action has been processed in the textbox
             if (event.action == KeyEvent.ACTION_UP)
-                button.isEnabled = editText.text.isNotBlank()
+                refreshButton()
 
             false
         })
@@ -40,14 +99,11 @@ class MainActivity : AppCompatActivity() {
             // Check that the task name has text in it
             if (editText.text.isBlank()) return@setOnClickListener
 
-            // Add task name to task list
-            taskList.add(editText.text.toString())
-
-            // Clear text box
-            editText.text.clear()
-
-            // Notify the adapter that data has changed
-            adapter.notifyItemInserted(taskList.size - 1)
+            taskList.add(editText.text.toString()) // Add task name to task list
+            editText.text.clear() // Clear text box
+            refreshButton() // Update button accordingly
+            adapter.notifyItemInserted(taskList.size - 1) // Notify the adapter that data has changed
+            saveData()
         }
     }
 }

app/src/main/java/com/embers/simpleto_do/TaskItemAdapter.kt

@@ -6,10 +6,25 @@ import android.view.ViewGroup
 import android.widget.TextView
 import androidx.recyclerview.widget.RecyclerView
 
-class TaskItemAdapter(private val taskList: List<String>) :
+class TaskItemAdapter(
+    private val taskList: List<String>,
+    private val longClickListener: OnLongClickListener
+) :
     RecyclerView.Adapter<TaskItemAdapter.ViewHolder>() {
+
+    interface OnLongClickListener {
+        fun onItemLongClicked(position: Int)
+    }
+
     inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
         val textView: TextView = itemView.findViewById(android.R.id.text1)
+
+        init {
+            itemView.setOnLongClickListener {
+                longClickListener.onItemLongClicked(bindingAdapterPosition)
+                true
+            }
+        }
     }
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {