added README & ResultOf

Author: LavishSwarnkar

.idea/vcs.xml

@@ -0,0 +1,51 @@
+# AndroidCommons
+
+Android library with common utilities required when building Android apps.
+
+---
+
+## Usage
+
+Step 1: Add JitPack in your **root build.gradle** :
+
+```groovy
+    allprojects {
+        repositories {
+            ...
+            maven { url 'https://jitpack.io' }
+        }
+    }
+```
+
+Step 2: Add AndroidCommons dependency to your **app build.gradle**:
+
+```groovy
+    dependencies {
+            implementation 'com.github.The-Streamliners:AndroidCommons:0.1.0'
+    }
+```
+
+---
+
+## Utilities
+
+### TasksInParallelHelper
+
+TasksInParallelHelper is a helper class that performs task in parallel. Any input type (I) & output type (O) is supported. By Implementing task class, you can perform any task on I to generate O, whether it be a long IO operation or a network call.
+
+[View examples](docs/TasksInParallelHelper.md)
+
+---
+
+### ResultOf<T>
+
+ResultOf is a resource wrapper class. While performing an IO / Network operation, there are 2 possibilities:
+
+- Task will be successful & we will get some data T
+
+- Task may fail producing some exception
+
+
+ResultOf<T> class makes it easier to wrap these 2 possibilities in one.
+
+[View examples & features](docs/ResultOf.md)

README.md

@@ -0,0 +1,37 @@
+package com.streamliners.commons
+
+sealed class ResultOf<T>(val data: T? = null, val message: String? = null) {
+
+    class Success<T>(data: T) : ResultOf<T>(data)
+
+    class Error<T>(message: String) : ResultOf<T>(message = message)
+
+    fun onSuccess(handler: (T) -> Unit): ResultOf<T> {
+        if(this is Success)
+            data?.let(handler)
+        return this
+    }
+
+    fun onFailure(handler: (String) -> Unit): ResultOf<T> {
+        if(this is Error)
+            message?.let(handler)
+        return this
+    }
+
+    fun finally(handler: () -> Unit): ResultOf<T> {
+        handler()
+        return this
+    }
+
+    fun await(): T {
+        if(this is Success)
+            data?.let {
+                return it
+            } ?: throw Exception("Something went wrong")
+        else
+            message?.let {
+                throw Exception(it)
+            } ?: throw Exception("Something went wrong")
+    }
+
+}

commons/src/main/java/com/streamliners/commons/ResultOf.kt

@@ -20,7 +20,7 @@ abstract class Task<I, O> {
 /**
  * TasksInParallelHelper is a helper class that performs task in parallel.
  * Any input type (I) & output type (O) is supported.
- * By Implementing task class, you can perform ny task on I to generate O.
+ * By Implementing task class, you can perform any task on I to generate O.
  * Whether it be a long IO operation or a network call.
  */
 class TasksInParallelHelper<I, O> {

commons/src/main/java/com/streamliners/commons/tasksInParallel/TasksInParallelHelper.kt

@@ -0,0 +1,100 @@
+# ResultOf<T>
+
+ResultOf is a resource wrapper class. While performing an IO / Network operation, there are 2 possibilities:
+
+- Task will be successful & we will get some data T
+
+- Task may fail producing some exception
+
+
+ResultOf class makes it easier to wrap these 2 possibilities in one.
+
+---
+
+## Code without ResultOf class
+
+You'll have to use try catch whenever calling a suspending function
+
+```kotlin
+try {
+    val user = userRepository.getUser()
+} catch(e: Exception) {
+    // Handle error
+}
+
+
+OR 
+
+
+coroutineScope.launch(exceptionHandler) {
+    val user = userRepository.getUser()
+}
+```
+
+## Using ResultOf class with when block
+
+```kotlin
+when(
+    val result = userRepository.getUser()
+) {
+    is Success -> {
+        val user = result.data
+        // Consume result
+    }
+    is Error -> {
+        val error = result.message
+        // Show error
+    }
+}
+```
+
+The code might look longer, but there are 2 functions at rescue :
+
+## Using ResultOf with onSuccess & onFailure
+
+```kotlin
+userRepository.getUser()
+    .onSuccess { user ->
+
+    }.onFailure { error ->
+
+    }
+```
+
+But these functions lead to callback hell when calling multiple suspending functions in a sequence:
+
+## Callback hell
+
+```kotlin
+userRepository.getUser()
+    .onSuccess { user ->
+        paymentsRepository.getPayments(user)
+            .onSuccess { payments ->
+
+            }.onFailure { error ->
+
+            }
+    }.onFailure { error ->
+
+    }
+```
+
+Is there a way out? Of course, ResultOf class offers await() method :
+
+## Using ResultOf class with await()
+
+```kotlin
+try {
+    val user = userRepository.getUser().await()
+    val payments = paymentsRepository.getPayments(user).await()
+} catch(e: Exception) {
+    // Handle error
+}
+
+OR 
+
+coroutineScope.launch(exceptionHandler) {
+    val user = userRepository.getUser().await()
+    val payments = paymentsRepository.getPayments(user).await()
+}
+```

docs/ResultOf.md

@@ -0,0 +1,96 @@
+# TasksInParallelHelper
+
+TasksInParallelHelper is a helper class that performs task in parallel. Any input type (I) & output type (O) is supported. By Implementing task class, you can perform any task on I to generate O, whether it be a long IO operation or a network call.
+
+---
+
+## Kotlin example
+
+Step 1: Prepare a list of inputs of any input type A
+
+```kotlin
+val inputs = listOf(A(1), A(2), A(3))
+```
+
+Step 2: Implement Task class to transform input type A into output type B
+
+```kotlin
+val task: Task<A, B> =
+    object : Task<A, B>() {
+        override fun perform(input: A, listener: Listener<B>) {
+            // Simple stupid task that converts int to String
+            val output = B(input.x.toString())
+            listener.onSuccess(output)
+        }
+    }
+```
+
+Step 3: Implement listener to get outputs of output type B
+
+```kotlin
+val listener: TasksListener<B> =
+    object : TasksListener<B> {
+        override fun onSuccess(outputs: List<B>) {
+            // Do something with the outputs
+        }
+
+        override fun onFailure(error: String) {
+            // Show the error!
+        }
+    }
+```
+
+Step 4: Finally perform the tasks in parallel!
+
+```kotlin
+TasksInParallelHelper<A, B>()
+        .doTasksInParallel(inputs, task, listener)
+```
+
+---
+
+## Java Example
+
+Step 1: Prepare a list of inputs of any input type A
+
+```kotlin
+List<A> inputs = Arrays.asList(new A(1), new A(2), new A(3));
+```
+
+Step 2: Implement Task class to transform input type A into output type B
+
+```kotlin
+Task<A, B> task =
+    new Task<A, B>() {
+        @Override
+           public void perform(A input, @NonNull Listener<B> listener) {
+                // Simple stupid task that converts int to String
+                B output = new B(String.valueOf(input.getX()));
+                listener.onSuccess(output);
+            }
+    };
+```
+
+Step 3: Implement listener to get outputs of output type B
+
+```kotlin
+TasksInParallelHelper.TasksListener<B> listener =
+    new TasksInParallelHelper.TasksListener<B>() {
+        @Override
+        public void onSuccess(@NonNull List<? extends B> outputs) {
+            // Do something with the outputs
+        }
+
+        @Override
+        public void onFailure(@NonNull String error) {
+            // Show the error!
+        }
+    };
+```
+
+Step 4: Finally perform the tasks in parallel!
+
+```kotlin
+new TasksInParallelHelper<A, B>()
+    .doTasksInParallel(inputs, task, listener);
+```