Java多線程 ExecutorService Callable Future使用

需求：查詢int數組中最大值

package test;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class ExecutorServiceTest {
	public static void main(String[] args) throws InterruptedException, ExecutionException {
		int[] data = {2,3,4,1};
		MultithreadMaxFinder mmf = new MultithreadMaxFinder();
		System.out.println(mmf.max(data));
	}
}

class MultithreadMaxFinder{
	public int max(int[] data) throws InterruptedException, ExecutionException{
		if(data.length == 1)
			return data[0];
		else if(data.length == 0)
			throw new IllegalArgumentException();
		
		ExecutorService es = Executors.newFixedThreadPool(2);
		FindMaxTask task1 = new FindMaxTask(data, 0, data.length/2);
		FindMaxTask task2 = new FindMaxTask(data, data.length/2, data.length);
		Future<Integer> future1 = es.submit(task1);
		Future<Integer> future2 = es.submit(task2);
		
		return Math.max(future1.get(), future2.get());
	}
}

class FindMaxTask implements Callable<Integer>{
	private int[] data;
	private int start;
	private int end;
	
	FindMaxTask(int[] data, int start, int end){
		this.data = data;
		this.start = start;
		this.end = end;
	}
	
	@Override
	public Integer call() throws Exception {
		int max = Integer.MIN_VALUE;
		for(int i=start; i<end; i++){
			if(data[i] > max)
				max = data[i];
		}
		return max;
	}
}