AsyncTask ~ Threading made easy :-)

This library provides a convininence API for creating async tasks. A task is a callable or a function that executes works syncronously and gives out the result. You can perform that heavy bloaking-task on a background thread and can publish the result on public thread with optional callbacks.

Implementation

Gradle

Add it in your root build.gradle at the end of repositories

	allprojects {
		repositories {
			...
			maven { url 'https://jitpack.io' }
		}
	}

Add the dependency in your module build.gradle

	dependencies {
	    implementation 'com.github.ErrorxCode:AsyncTask:1.0'
	}

Maven

Declare the repositories

	<repositories>
		<repository>
		    <id>jitpack.io</id>
		    <url>https://jitpack.io</url>
		</repository>
	</repositories>

Add the dependency

	<dependency>
	    <groupId>com.github.ErrorxCode</groupId>
	    <artifactId>AsyncTask</artifactId>
	    <version>1.0</version>
	</dependency>

Usage/Examples

Creating task

To run your code asynchronously, wrap it in a Callable and pass it to callAsync() method.

Example:

AsyncTask task = AsyncTask.callAsync(() -> {
    ...    // do some blocking work
    return fetchSomethingOrThrow();
});

It takes a callable which if returns the value, the task is considered successful. If the callable throws an exception, the task is considered failed.

Fetching task results

This method will immediately return the task and your code would be running in a background thread. Now you can set a listener for getting the result.

task.setOnSuccessCallback(result -> {
    // your callable return value is here
}).setOnErrorCallback(e -> {
    // your callable exception is here
});

or else,

task.setOnCompleteCallback(task -> {
    if (task.isSuccessful){
        // Success, get the result
        Object result = task.result;
    } else {
        // Error, get the exception
        Exception e = task.exception;
    }
});

Chaining tasks

If you have multimple tasks and every next tasks depends on previous tasks result then you can chain them using thenPerform() method.

Example:

placeOrder("Plain rice")
        .thenPerform((AsyncFunction<String, String>) dish -> getOrderId(dish))
        .thenPerform((AsyncFunction<String, Integer>) id -> getOrderPrice(id))
        .thenPerform((AsyncFunction<Integer, Void>) price -> payAndEnque(price))
        .setOnSuccessCallback(result -> System.out.println("Order placed successfully"))
        .setOnErrorCallback(e -> System.out.println("Order failed"));

In this example, we have a placeOrder task which places a order with the dish name. Once the first task completed, its result i.e dish code is deliver to the next thenPerform() method. This same thing happens till the last task and then finally overall result is called. If any of the task is failed, the overall result fails.

If you have multiple tasks but they are independent of each other, you can join all of them to build a single task using AsyncTask.allOff() method.

Example

AsyncTask<String> task1 = getTask();
AsyncTask<Integer> task2 = getTask();
AsyncTask<Boolean> task3 = getTask();

AsyncTask.allOf(task1, task2, task3)
        .setOnSuccessCallback(result -> {
            // Overall success
            System.out.println("All tasks completed successfully");
        })
        .setOnErrorCallback(e -> {
            // Overall error
            System.out.println("Any of the tasks failed");
        });

Syncronous approch

If you want the result immediately and don't want to move further, you can use getResult() method. This method will block the thread until the timed out or result is fetched.

Example:

try {
    String result = task.getResult(5);
} catch (Exception e) {
    // Failed
}

That's it

That is all about what you need to know before implimenting it in your program. A gread way would be to return the tasks from the methods of your API/library/class so that client can handle it accordingly.