java - fo循环中增加Runnable线程

Question

1 我有一个程序需要在for 循环中增加 Runnable，现在发现他执行的顺序是从上往下 ，不是多线程的方式执行

2 代码如下
public void addUserACard() {

    
    ThreadLbData tLbData = null;
    DbBean dbBean = null ;
    
    List<DataBase> listData = dataDAO.findHql(" from DataBase where state = '1'  order by createDate desc ");
    DataBase data = null ;
    if(listData != null && listData.size()> 0){
        for (int i = 0; i < listData.size(); i++) {
            data = listData.get(i);
            dbBean =  createDbBean(data);
            tLbData = new ThreadLbData(dbBean);
            tLbData.run();
        }
    }
}

}

@SuppressWarnings("unchecked")
public class ThreadLbData implements Runnable {

private DbBean dataBase;
private Map map = new HashMap();
private static ConnectionPools connectionPools = ConnectionPools.getInstance();

public ThreadLbData(DbBean dataBase) {
    this.dataBase = dataBase;
}



public void run() {
    
    Connection conn = connectionPools.getConnectionOracle(); // 获得JDBC链接;
    try {
        String lbMaxId = this.getSynLogMaxId(dataBase, conn);
        Map map = getLbDate(lbMaxId);
        saveAll((List<ReaderCard>) map.get("listCard"), (List<Userinfo>)   map.get("listUser"), conn);
    } catch (Exception e) {
        e.printStackTrace();
    }finally{
        connectionPools.close(null, null, conn);
    }
}

}

3 想让大神帮我看看，线程的run能不能并行，并且帮我改进，跪谢！

Answer 1

用线程池呗!

private ExecutorService executorService = Executors.newFixedThreadPool(10);
public void addUserACard() {
    
    ThreadLbData tLbData = null;
    DbBean dbBean = null ;
    
    List<DataBase> listData = dataDAO.findHql(" from DataBase where state = '1'  order by createDate desc ");
    DataBase data = null ;
    if(listData != null && listData.size()> 0){
        for (int i = 0; i < listData.size(); i++) {
            data = listData.get(i);
            dbBean =  createDbBean(data);
            executorService.execute(tLbData);
        }
    }
}

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private ExecutorService executorService = Executors.newFixedThreadPool(10);

上面的 Executors.newFixedThreadPool(10) 是创建了一个固定大小为10的线程池.
然后通过 executorService.execute( Runnable runnable) 的方式提交一个任务, 这样可以最大并行地执行10个任务. 如果需要并行的线程更多, 那么 Executors.newFixedThreadPool(threadCount) 的参数可以设置大一些.

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我要吐槽一下, 你应该是把 Runnable 接口和 Thread 类混淆了吧? 实现 Runnable 接口的类不代表它就是在一个新的线程中运行, 你必须显示地地将 Runnable 提交到新线程中执行, 例如 executorService.execute(runnable) 或 new Thread(runnable).start().

Answer 2

不能直接调用run方法，线程的执行要通过Thread.start方法。直接调用run方法和调用普通方法没有区别。

new Thread(tLbData).start()