I am having a run method which tries to override another run method. But its not happening because I am getting a "Class not found Exception" before it passed on to run method.
Here´s my class with run method
How could I get this over ride the run method.
the class which I have to call in order to execute.
public abstract class MessageProcessor implements Runnable {
private Collection<KpiMessage> fetchedMessages;
private Connection dbConnection;
Statement st = null;
ResultSet rs = null;
PreparedStatement pstmt = null;
private Collection<KpiMessage> outgoingQueue;
public KpiMsg804 MessageProcessor(Collection<KpiMessage> outgoingQueue, Connection
dbConnection){
this.outgoingQueue = outgoingQueue;
this.dbConnection = dbConnection;
return (KpiMsg804) fetchedMessages;
}
public Collection<KamMessage> generate(Collection<KamMessage> outgoingQueue)
{
while(true){
try {
while (rs.next()) {
KamMessage filedClass = convertRecordsetToPojo(rs);
outgoingQueue.add(filedClass);
}
for (KamMessage pojoClass : outgoingQueue) {
KamMsg804 updatedValue = createKamMsg804(pojoClass);
System.out.print(" " + pojoClass.getSequence());
System.out.print(" " + pojoClass.getTableName());
System.out.print(" " + pojoClass.getAction());
System.out.print(" " + updatedValue.getKeyInfo1());
System.out.print(" " + updatedValue.getKeyInfo2());
System.out.println(" " + pojoClass.getEntryTime());
}
return outgoingQueue;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
In your code you are creating a default-visibility field inside a class, and not overriding the run() method. Just stick to:
MessageProcessor processor = new MessageProcessor() {
#Override
final public void run() {
MessageProcessor(outgoingQueue).generate(outgoingQueue);
}
};
And remove the outer MessageProcessor declaration.
I made a subset of your code:
public class PollingSynchronizer {
public static void main(String[] args) {
MessageProcessor message = new MessageProcessor() {
MessageProcessor message = new MessageProcessor() {
public void run() {
System.out.println("new run");
}
};
};
new Thread(message).start();
}
}
class MessageProcessor implements Runnable {
public void run() { System.out.println("old run"); }
}
Which will print old run because the first MessageProcessor::run() it is not really being overwritten.
Related
I'm trying to create an object in one class then use that object in another class but each time I try to use it it just says the value is null
Customer cus = new Customer();
ServerSocket s = null;
public AddCustomer() {
}
public void getCustomerDetail() {
String back = " ";
{
try {
s = new ServerSocket(5433);
} catch (IOException e) {
System.out.println("Error:" + e.getMessage());
System.exit(0);
}
while (back.equals(" ")) {
try {
Socket s1 = s.accept();
System.out.println("Connection established at port 5433");
InputStream is = s1.getInputStream();
ObjectInputStream dis = new ObjectInputStream(is);
System.out.println("Getting data...");
cus = (Customer)dis.readObject();
System.out.println(cus.toString());
System.out.println(cus.getName());
dis.close();
s1.close();
System.out.println("Connection closed.");
} catch (ConnectException connExcep) {
System.out.println("1Error: " + connExcep.getMessage());
} catch (IOException ioExcep) {
System.out.println("2Error: " + ioExcep.getMessage());
} catch (Exception e) {
System.out.println("3Error: " + e.getMessage());
}
new AddCustomer().addCustomerToDB();
}
}
}
public void addCustomerToDB() {
System.out.println("start ");
Connection connection = null;
Statement statement = null;
int check = 1;
System.out.println(cus.getName()+"dadawd");
}
When I print out the value of cus.getName() it just gives me null but when I print it out in getCustomerDetail it gives me the correct value.
dis.readObject returns an object with the values in it.
Depends on what you are doing in the getName function and in the constructor.
Maybe in getCustomerDetails() you are setting the values in the input stream. But the default constructor doesn't do anything with name variable.
It looks like the issue of packaging. Try below code.
public class AddCustomer {
public static void main(String[] args) {
new AddCustomer().getCustomerDetail();
}
Customer cus = new Customer();
public void getCustomerDetail() {
String back = " ";
{
while (back.equals(" ")) {
try {
System.out.println(cus.toString());
System.out.println(cus.getName());
System.out.println("Connection closed.");
} catch (Exception e) {
System.out.println("3Error: " + e.getMessage());
}
new AddCustomer().addCustomerToDB();
break;
}
}
}
public void addCustomerToDB() {
System.out.println(cus.getName()+"dadawd");
}
}
class Customer{
private String name="ABC";
String getName() {
return name;
}
}
We found here one issue you have to create "Customer cus = new Customer();" this object under main() function like as
public class AddCustomer {
public static void main(String[] args) {
Customer cus = new Customer();
new AddCustomer().getCustomerDetail();
}
I’m working on the task of monitoring the execution of query, it became necessary to check the query after a certain time. Please, help me, how to implement the method poll correctly? Is it possible to do this in a separate thread? For example, I want to log every iteration of the loop and end the stream on the number 8. how to implement it correctly? Thanks!
public class MyTimerTask implements Runnable {
String name;
private boolean isActive;
void disable(){
isActive=false;
}
MyTimerTask(String name){
isActive = true;
this.name = name;
run();
}
#Override
public void run() {
System.out.println(name + " Start at :" + new Date());
try {
completeTask();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(name + " Finish at:" + new Date());
}
private void completeTask() throws InterruptedException {
for(int i = 0; i<10;i++){
System.out.println(i);
Thread.sleep(1000);
}
}
public static void main(String args[]){
new MyTimerTask("device");
}
}
Try something like this:
public class MyTimerTask implements Runnable {
#Override
public void run() {
System.out.println(name + " Start at :" + new Date());
completeTask();
System.out.println(name + " Finish at:" + new Date());
}
private void completeTask() throws InterruptedException {
for(int i = 0; i<10;i++){
System.out.println(i);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args){
new Thread(new MyTimerTask(), "device").start();
}
}
Do not need those fields, java.lang.Thread have those.
Do not call methods from the constructor that requires the instance to be fully created. EG: do not call run() from it.
InterruptedExceptions should be caught, but in this case you may want to swallow it, as it is not signalling an unfinished job...
To create a new thread use the Thread: You can specify the Runnable instance and/or name as arguments of the constructor. Or you can extend it and call super() with the name in the constructor, and implement run() in it.
.
public class MyTimerTask extends Thread {
public MyTimerTask() {
super("device");
}
#Override
public void run() {
System.out.println(name + " Start at :" + new Date());
completeTask();
System.out.println(name + " Finish at:" + new Date());
}
private void completeTask() throws InterruptedException {
for(int i = 0; i<10;i++){
System.out.println(i);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args){
new Thread().start();
}
}
You implementation works fine.
You just need include on main method:
public static void main(String args[]){
new Thread(new MyTimerTask("device")).start();
}
Have in mind that according this implementation you'll run the function only 10 times.
As you have a status flag maybe you can use it changing the loop intructoin.
while (isActive) {
System.out.println(name + " Start at :" + Instant.now());
I am trying to do multi-threading here, now I have to update my database using DbHandler class
The program execution begins in a controller class which has a main method and a thread pool:
public class RunnableController {
// Main method
public static void main(String[] args) throws InterruptedException {
try {
RunnableController controller = new RunnableController();
controller.initializeDb();
controller.initialiseThreads();
System.out.println("Polling");
} catch (Exception e) {
e.printStackTrace();
}
}
private void initialUpdate()
{
DBhandler dbhandler = new DBhandler();
dbhandler.updateDb(getOutgoingQueue());
}
private void initialiseThreads() {
try {
threadExecutorRead = Executors.newFixedThreadPool(10);
PollingSynchronizer read = new PollingSynchronizer(incomingQueue, dbConncetion);
threadExecutorRead.submit(read);
} catch (Exception e){
e.printStackTrace();
}
}
}
My poller class which fetches new data and should do updating simulateously:
public class PollingSynchronizer implements Runnable {
public PollingSynchronizer(Collection<KamMessage> incomingQueue,
Connection dbConnection) {
super();
this.incomingQueue = incomingQueue;
this.dbConnection = dbConnection;
}
private int seqId;
public int getSeqId() {
return seqId;
}
public void setSeqId(int seqId) {
this.seqId = seqId;
}
// The method which runs Polling action and record the time at which it is done
public void run() {
int seqId = 0;
while (true) {
List<KamMessage> list = null;
try {
list = fullPoll(seqId);
if (!list.isEmpty()) {
seqId = list.get(0).getSequence();
incomingQueue.addAll(list);
this.outgoingQueue = incomingQueue;
System.out.println("waiting 3 seconds");
System.out.println("new incoming message");
Thread.sleep(3000);//at this wait I should execute run()
//when I debug my execution stops here and throws " Class not found Exception "
// its does not enters the message processor class
MessageProcessor processor = new MessageProcessor() {
//the run method which should fetch the message processor class.
final public void run() {
RunnableController.setOutgoingQueue(generate(outgoingQueue));
}
};
new Thread(processor).start();
}
} catch (Exception e1) {
e1.printStackTrace();
}
}
}
}
My message processor class:
public class MessageProcessor implements Runnable {
private Collection<KpiMessage> fetchedMessages;
private Connection dbConnection;
Statement st = null;
ResultSet rs = null;
PreparedStatement pstmt = null;
private Collection<KamMessage> outgoingQueue;
public Collection<KamMessage> MessageProcessor(Collection<KamMessage> outgoingQueue){
this.outgoingQueue = outgoingQueue;
this.dbConnection = dbConnection;
return outgoingQueue;
}
/**
* Method for updating new values into database in preference for dummy processing of message
* #param outgoingQueue
* #return
*/
#SuppressWarnings("javadoc")
public Collection<KamMessage> generate(Collection<KamMessage> outgoingQueue)
{
for (KamMessage pojoClass : outgoingQueue) {
KamMessage updatedValue = createKamMsg804(pojoClass);
System.out.print(" " + pojoClass.getSequence());
System.out.print(" " + pojoClass.getTableName());
System.out.print(" " + pojoClass.getAction());
System.out.print(" " + updatedValue.getKeyInfo1());
System.out.print(" " + updatedValue.getKeyInfo2());
System.out.println(" " + pojoClass.getEntryTime());
}
return outgoingQueue;
}
/**
*
* #param pojoClass
* #return msg
*/
public KamMessage createKamMsg804(KamMessage pojoClass)
{
if(pojoClass.getAction() == 804){
pojoClass.setKeyInfo1("ENTITYKEY9");
pojoClass.setKeyInfo2("STATUSKEY9");
}
return pojoClass;
}
private KamMessage convertRecordsetToPojo(ResultSet rs) throws SQLException {
KamMessage msg = new KamMessage();
int sequence = rs.getInt("SEQ");
msg.setSequence(sequence);
String tablename = rs.getString("TABLENAME");
msg.setTableName(tablename);
Timestamp entrytime = rs.getTimestamp("ENTRYTIME");
Date entryTime = new Date(entrytime.getTime());
msg.setEntryTime(entryTime);
Timestamp processingtime=rs.getTimestamp("PROCESSINGTIME");
if(processingtime!=null){
Date processingTime = new Date(processingtime.getTime());
msg.setProcessingTime(processingTime);
}
String keyInfo1 = rs.getString("KEYINFO1");
msg.setKeyInfo1(keyInfo1);
String keyInfo2 = rs.getString("KEYINFO2");
msg.setKeyInfo2(keyInfo2);
return msg;
}
#Override
public void run() {
// TODO Auto-generated method stub
}
}
This is my DBhandler Class, which should do updating in database
public class DBhandler {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
PreparedStatement pstmt = null;
public DBhandler(){
super();
}
/**
* Method to initialize the database connection
* #return conn
* #throws Exception
*
*/
public Connection initializeDB() throws Exception {
System.out.println("JDBC connection");
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
conn = DriverManager.getConnection("jdbc:oracle:thin:#VM-SALES-
MB:1521:SALESDB1","bdeuser", "edb"); // Connection for Database SALES-DB1
return conn;
}
//The method for updating Database
public void updateDb(Collection<KpiMessage> updatedQueue){
for(KpiMessage pojoClass : updatedQueue){
//**How the query should be used so that it gets last sequence vale and Updates into
Database**
String query = "UPDATE msg_new_to_bde Set KEYINFO1= ?, KEYINFO2 = ? WHERE SEQ = and
action = 804";
}
}
/**
* Method for Closing the connection
* #throws Exception
*
*/
public void closeDB() throws Exception {
st.close();
conn.close();
}
}
I just need to Update the database using update query in this class(DbHAndler) by calling the updatedQueue in the controller class.
My program flow - I have three classes: 1.Controller 2.PollerSynchro 3.Msgprocessor
I have database records, which are converted into POJO form and stored in a Collection. With these POJOs my classes try to do multiprocessing and updating in a single stretch.
Controller - has the thread pool, initiates poller class with poll method - done
Poller - should poll for new incoming messages and stores it in incoming queue - done
MsgProcessor - should look for new incoming messages and pass them from outgoing queue to incoming queue - also done
DbHandler- which should update in the database.
Problem:
Now my problem is
I have to implement this update while the poll thread sleeps for 3 sec -Done
In my code for the second void run() method in the Poller class, the outgoing queue is not passed and fed to the messageprocessor class for updating. My flow of execution only just loops back to first run method and am getting Class exception-Resolved
How to Update this in the database in Dbhanler class
Please help me to solve these problems.
The exception seems to come from this line (is this MessageProcessor.java line 38?)
return (KpiMsg804) fetchedMessages;
The fetchedMessages at this point seem to be an ArrayList.
I have a problem where my class is performing the first run method after which it is not proceeding into a second, overidden run method.
The program execution beings in a controller class which has a main method and a thread pool:
public class RunnableController {
// Main method
public static void main(String[] args) throws InterruptedException {
try {
RunnableController controller = new RunnableController();
controller.initializeDb();
controller.initialiseThreads();
System.out.println("Polling");
} catch (Exception e) {
e.printStackTrace();
}
}
private void initialiseThreads() {
try {
threadExecutorRead = Executors.newFixedThreadPool(10);
PollingSynchronizer read = new PollingSynchronizer(incomingQueue, dbConncetion);
threadExecutorRead.submit(read);
} catch (Exception e){
e.printStackTrace();
}
}
}
My poller class which fetches new data and should do updating simulateously:
public class PollingSynchronizer implements Runnable {
public PollingSynchronizer(Collection<KamMessage> incomingQueue,
Connection dbConnection) {
super();
this.incomingQueue = incomingQueue;
this.dbConnection = dbConnection;
}
private int seqId;
public int getSeqId() {
return seqId;
}
public void setSeqId(int seqId) {
this.seqId = seqId;
}
// The method which runs Polling action and record the time at which it is done
public void run() {
int seqId = 0;
while (true) {
List<KamMessage> list = null;
try {
list = fullPoll(seqId);
if (!list.isEmpty()) {
seqId = list.get(0).getSequence();
incomingQueue.addAll(list);
this.outgoingQueue = incomingQueue;
System.out.println("waiting 3 seconds");
System.out.println("new incoming message");
Thread.sleep(3000);//at this wait I should execute run()
//when I debug my execution stops here and throws " Class not found Exception "
// its does not enters the message processor class
MessageProcessor processor = new MessageProcessor() {
//the run method which should fetch the message processor class.
final public void run() {
MessageProcessor(outgoingQueue).generate(outgoingQueue);
}
};
new Thread(processor).start();
}
} catch (Exception e1) {
e1.printStackTrace();
}
}
}
}
My message processor class:
public abstract class MessageProcessor implements Runnable {
private Connection dbConnection;
Statement st = null;
ResultSet rs = null;
PreparedStatement pstmt = null;
private Collection<KamMessage> outgoingQueue;
public KamMsg804 MessageProcessor(Collection<KamMessage> outgoingQueue,
Connection dbConnection) {
this.outgoingQueue = outgoingQueue;
this.dbConnection = dbConnection;
return (KpiMsg804) fetchedMessages;
}
public Collection<KamMessage> generate(Collection<KamMessage> outgoingQueue) {
while (true) {
try {
while (rs.next()) {
KamMessage filedClass = convertRecordsetToPojo(rs);
outgoingQueue.add(filedClass);
}
for (KamMessage pojoClass : outgoingQueue) {
KamMsg804 updatedValue = createKamMsg804(pojoClass);
System.out.print(" " + pojoClass.getSequence());
System.out.print(" " + pojoClass.getTableName());
System.out.print(" " + pojoClass.getAction());
System.out.print(" " + updatedValue.getKeyInfo1());
System.out.print(" " + updatedValue.getKeyInfo2());
System.out.println(" " + pojoClass.getEntryTime());
}
return outgoingQueue;
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
My problem is exactly at the second run(9 method where I am getting exception in MessageProcessor class and it loops back to Polling.
How do I implement multithreading here, as when the thread sleeps for 3 seocnds in polling it should simultaneously update the database.
After which, how can the data be fed and updated back into the db.
My program flow - I have three classes:
1.Controller
2.PollerSynchro
3.Msgprocessor
I have database records, which are converted into POJO form and stored in a Collection. With these POJOs my classes try to do multiprocessing and updating in a single stretch.
Controller - has the thread pool, initiates poller class with poll method - done
Poller - should poll for new incoming messages and stores it in incoming queue - done
MsgProcessor - should look for new incoming messages and pass them from outgoing queue to incoming queue - also done
Problem:
Now my problem is
I have to implement this update while the poll thread sleeps for 3 sec,
In my code for the second void run() method in the Poller class, the outgoing queue is not passed and fed to the messageprocessor class for updating. My flow of execution only just loops back to first run method and am getting Class exception.
Please help me to solve these problems.
I can't sugar coat this, your code is a mess. However, as far as why your message processor code is not being executed, you never actually start the thread you created with this code:
MessageProcessor processor = new MessageProcessor() {
// the run method which should fetch the message processor class.
final public void run() {
MessageProcessor(outgoingQueue).generate(outgoingQueue);
}
};
Ignoring the confusingly named method being called, your code should look more like this:
Message processor = new MessageProcessor() {
// the run method which should fetch the message processor class.
final public void run() {
MessageProcessor(outgoingQueue).generate(outgoingQueue);
}
};
new Thread(processor).start();
Now basically I have created three classes.
public void run() {
int seqId = 0;
while(true) {
List<KamMessage> list = null;
try {
list = fullPoll(seqId);
} catch (Exception e1) {
e1.printStackTrace();
}
if (!list.isEmpty()) {
seqId = list.get(0).getSequence();
incomingMessages.addAll(list);
System.out.println("waiting 3 seconds");
System.out.println("new incoming message");
}
try {
Thread.sleep(3000);
System.out.println("new incoming message");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public List<KamMessage> fullPoll(int lastSeq) throws Exception {
Statement st = dbConnection.createStatement();
ResultSet rs = st.executeQuery("select * from msg_new_to_bde where ACTION = 804 and SEQ >" +
lastSeq + "order by SEQ DESC");
List<KamMessage> pojoCol = new ArrayList<KamMessage>();
while (rs.next()) {
KamMessage filedClass = convertRecordsetToPojo(rs);
pojoCol.add(filedClass);
}
for (KamMessage pojoClass : pojoCol) {
System.out.print(" " + pojoClass.getSequence());
System.out.print(" " + pojoClass.getTableName());
System.out.print(" " + pojoClass.getAction());
System.out.print(" " + pojoClass.getKeyInfo1());
System.out.print(" " + pojoClass.getKeyInfo2());
System.out.println(" " + pojoClass.getEntryTime());
}
return pojoCol;
}
The following are the classes:
1.Poller- does the Polling and Passes the new data from db to controller
2.Controller- this class has a thread Pool, which simultaneously calls the Poller and has the new data to be requested from processor
3.Processor- this class has to look for new data, process it and return it to controller.
So now my problem is how to implement the third phase...
Here is my controller class:
public class RunnableController {
/** Here This Queue initializes the DB and have the collection of incoming message
*
*/
private static Collection<KpiMessage> incomingQueue = new ArrayList<KpiMessage>();
private Connection dbConncetion;
public ExecutorService threadExecutor;
private void initializeDb()
{
//catching exception must be adapted - generic type Exception prohibited
DBhandler conn = new DBhandler();
try {
dbConncetion = conn.initializeDB();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private void initialiseThreads()
{
try {
threadExecutor = Executors.newFixedThreadPool(10);
PollingSynchronizer read = new PollingSynchronizer(incomingQueue, dbConncetion);
threadExecutor.submit(read);
}catch (Exception e){
e.printStackTrace();
}
}
#SuppressWarnings("unused")
private void shutDownThreads()
{
try {
threadExecutor.shutdown();
//DB handling should be moved to separate DB class
dbConncetion.close();
}catch (Exception e){
e.printStackTrace();
}
}
/** Here This Queue passes the messages and have the collection of outgoing message
*
*/
//private Collection<KpiMessage> outgingQueue = new ArrayList<KpiMessage>();
//have to implement something here for future
public static void main(String[] args) throws InterruptedException {
RunnableController controller = new RunnableController();
System.out.println(incomingQueue.size());
controller.initializeDb();
controller.initialiseThreads();
Thread.sleep(3000);
System.out.println("Polling");
}
}
I would recommend using a BlockingQueue for doing so, instead of a simple ArrayList. Just change the type of your incomingQueue variable. Then you can have another thread (or a thread pool) doing something like
//pseudocode
while (true) {
// it polls data from the incomingQueue that shares with the producers
KpiMessage message = this.incomingQueue.take()
//Then process the message and produces an output... you can put that output in a different queue as well for other part of the code to pick it up
}
A good example on BlockingQueues can be found here http://www.javamex.com/tutorials/blockingqueue_example.shtml