无法使用Java线程

Question

我想每秒插入数据库4个数据。同时让每个线程等待并一起唤醒。然后每个线程进入休眠状态1秒钟，整个过程将重复。我面临的问题是这里DATA值没有增加，在运行程序之后，它会继续将数据插入数据库，直到强制停止/终止，插入0后，下一个数据显示2.如何解决这个问题？

以下是我得到的输出

08-JUL-16 07.43.42.721000 AM    0
08-JUL-16 07.43.42.731000 AM    2
08-JUL-16 07.43.42.731000 AM    2
08-JUL-16 07.43.42.731000 AM    2
08-JUL-16 07.43.42.731000 AM    2
.
.
.

08-JUL-16 07.43.43.815000 AM    2
08-JUL-16 07.43.43.815000 AM    2
08-JUL-16 07.43.43.825000 AM    2
.
.

这是我的代码

public class TestMainConnection {

public static void main(String[] args) {
    Thread t1=new Thread(new TestingThread(),"t1");
    Thread t2=new Thread(new TestingThread(),"t2");
    Thread t3=new Thread(new TestingThread(),"t3");
    Thread t4=new Thread(new TestingThread(),"t4");
    t1.start();
    t2.start();
    t3.start();
    t4.start();
}

}

public class TestingThread implements Runnable {
    @Override
    public void run() {
        try {
            Thread.sleep(1000);
            doDBProcessing();
        }
        catch(InterruptedException e){
            System.out.println(e);
        }
    }
    private void doDBProcessing() throws InterruptedException {
        Connection conn=null;
        PreparedStatement pstmt;
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            conn= DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521/xe","SYSTEM","sd");

            String insertQuery = "Insert into k(workdate,data) values(?,?)";
            pstmt = conn.prepareStatement(insertQuery);
            for(int i=0;i<1000;i++) {
                pstmt.setTimestamp(1, getCurrentTimeStamp());
                pstmt.setLong(2, i);
                i=pstmt.executeUpdate();
            }
            System.out.println("Data Successfully Uploaded");   
            pstmt.close();
            conn.commit();
            conn.close();
        } catch(SQLException se) {
            se.printStackTrace();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

    private static java.sql.Timestamp getCurrentTimeStamp() {
        java.util.Date today = new java.util.Date();
        return new java.sql.Timestamp(today.getTime());
    }
}