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Question about the task

Caching

Java Multithreading, Level 9, Lesson 9

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Should I create an anonymous class inside method or where? And how should I return the created instance?

In CacheComputeManager, implement the logic of the empty method.
Guess what it should do based on the method name and the class's logic.

Requirements:

The createFutureTaskForNewArgumentThatHasToComputeValue() method should create and return a FutureTask object.
The createFutureTaskForNewArgumentThatHasToComputeValue() method must create an instance of an anonymous class that implements the Callable interface.
The createFutureTaskForNewArgumentThatHasToComputeValue() method should include the line "return computable.compute(arg);"should appear.
The program should display the text indicated in the comments in the Solution class.

package com.codegym.task.task29.task2908; /* Caching */ public class Solution { public static void main(String[] args) throws InterruptedException { //////////////First example/////////////////// Square square = new Square(); CacheComputeManager<Integer, Integer> manager = new CacheComputeManager(square); for (int i = 0; i < 8; i++) { int j = i % 4; Integer result = manager.compute(j); System.out.format("%d * %d = %d\n", j, j, result); } /* Output 0 will be cached 0 * 0 = 0 1 will be cached 1 * 1 = 1 2 will be cached 2 * 2 = 4 3 will be cached 3 * 3 = 9 0 taken from cache 0 * 0 = 0 1 taken from cache 1 * 1 = 1 2 taken from cache 2 * 2 = 4 3 taken from cache 3 * 3 = 9 */ //////////////Second example/////////////////// Copyright copyright = new Copyright(); CacheComputeManager manager2 = new CacheComputeManager(copyright); System.out.println(manager2.compute(new Copyright.Period(3012, 3147))); System.out.println(manager2.compute(new Copyright.Period(3012, 3146))); System.out.println(manager2.compute(new Copyright.Period(3012, 3147))); /* Output Period{firstYear=3012, secondYear=3147} will be cached All rights reserved (C) 3012-3147 Period{firstYear=3012, secondYear=3146} will be cached All rights reserved (C) 3012-3146 Period{firstYear=3012, secondYear=3147} taken from cache All rights reserved (C) 3012-3147 */ } }

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Skynet

Level 40 , USA

5 June 2020, 05:44

solution

Reset the task. What you need to do is in the createFutureTaskForNewArgumentThatHasToComputeValue() method "return new FutureTask<Value>().." object and inside this object create an anonymous Callable class. Inside the Callable class override the call() method by returning the line as described in Requirement n.3

Jonas

Level 41 , Vilnius, Lithuania

5 June 2020, 08:26

Thanks for your feedback. I updated my code to this: public FutureTask<Value> createFutureTaskForNewArgumentThatHasToComputeValue(final Argument arg) { class Anonymous implements Callable { @Override public Object call() throws Exception { return computable.compute(arg); } } return new FutureTask<Value>(new Anonymous()); } But it's failing second requirement, could you give me a hint?

Skynet

Level 40 , USA

5 June 2020, 08:58

Try to create the new Callable inside the () of return new FutureTask<Value>

Jonas

Level 41 , Vilnius, Lithuania

5 June 2020, 09:05

How should it look like? return new FutureTask<Value>( class Anonymous implements Callable { @Override public Object call() throws Exception { return computable.compute(arg); } }); this doesn't compile, how should I modify it?

Jonas

Level 41 , Vilnius, Lithuania

5 June 2020, 09:07

Oh, I got it, thank you very much

Skynet

Level 40 , USA

5 June 2020, 09:11

No problem.