Java多线程 ExecutorService Callable Future使用

浅浅的花香味﹌ 2023-07-25 08:40 13阅读 0赞

需求：查询int数组中最大值

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;
    	}
    }