I'm running a program that connects to a device which in turn sends me data.
The data comes in as a String and then I process it accordingly to make an attempt to store it into my database using prepared statements.
I catch a null pointer exception that seems to come from the prepared statements. I figure this to be the problem because the exception goes away when I comment the code. Maybe I don't understand prepared statements as well as I think I do. Any suggestions please?
Here is most of my code:
String[] dataIn = new String[100];
int i, channel, state, theStamp, temp, temp2;
char first, second;
String[] toBinary = new String[100];
StringBuilder sb = new StringBuilder(40);
static String hexToBin(String s) {
return new BigInteger(s, 16).toString(2);
}
public void run() {
// Run as long as the thread is alive
while (this.threadAlive) {
try {
// Attempt to connect to the device.
if (super.connectToDevice()) {
// Send the data command to the device. If it is a test device, send the TIME command, otherwise send the DATA command
if (this.testDevice)
out.println(COMMAND_TIME);
else
out.println(COMMAND_DATA);
// Read and store the data returned from the device
String data = in .readLine();
//******//
System.out.println("The data: " + data);
//Splitting data into array
String criteria = " ";
if (data != null) {
dataIn = data.split(criteria);
toBinary[0] = hexToBin(dataIn[0]);
System.out.println("This is dataIn[0] before binary " + dataIn[0]); //testing
System.out.println("This is toBinary[0] " + toBinary[0]); //testing
temp = 0;
temp2 = 1;
for (i = 1; i < dataIn.length; i++) {
if (i % 2 == 0) {
toBinary[i / 2] = hexToBin(dataIn[i]);
System.out.println("Binary in String: " + toBinary[i / 2]);
try {
PreparedStatement ps = this.db.getConnection().prepareStatement(PreparedStatementStatics.INSERT_C1_DATA);
for (int j = 3; j < 27; j++) {
first = toBinary[temp].charAt(j);
second = toBinary[temp2].charAt(j);
System.out.println("Checkpoint first/second achieved.");
System.out.println("Temp = " + temp);
System.out.println("Temp2 = " + temp2);
if (first == second) {
sb.append(0);
} else {
sb.append(1);
}
//System.out.print("sb appends: " + sb);
}
temp++;
temp2++;
System.out.println("sb turns out to be " + sb);
channel = sb.indexOf("1", 0);
state = toBinary[0].charAt(channel);
System.out.println("Change occurred in channel " + channel);
sb.setLength(0);
ps.setInt(1, channel);
ps.setInt(2, state);
ps.addBatch();
ps.executeBatch();
ps.close();
ps = null;
} catch (NullPointerException ex) {
System.out.println("Null Pointer Exception: Not enough data this time through");
} catch (StringIndexOutOfBoundsException ex) {
System.out.println("Out of Bounds Exception");
} catch (SQLException e) {
System.out.println("Something is wrong with SQL");
e.printStackTrace();
}
} else {
System.out.println("This should be a timestamp: " + dataIn[i]);
}
}
}
UPDATE
Here is my console log when I run the code:
The data: 5ABFE000 2556923 52BFE000 2556b6a 5ABFE000 2556dfb 4ABFE000 2556f8e 4AB7E000 25570da 4ABFE000 2557225 4ABDE000 255739e 4ABFE000 255765a 4ABFA000 2557844 4ABF2000 2557959 4ABFA000 2557b36 4ABFE000 2557bc2 4ABFA000 2557d3f 4ABF8000 2557dc3 4ABFC000 2557f90 4ABFE000 2558013 4AB7E000 25582fa 4AA7E000 2558487 4AB7E000 25586f0 4ABFE000 2558772
This is dataIn[0] before binary 5ABFE000
This is toBinary[0] 1011010101111111110000000000000
This should be a timestamp: 2556923
Binary in String: 1010010101111111110000000000000
Null Pointer Exception: Not enough data this time through
This should be a timestamp: 2556b6a
Binary in String: 1011010101111111110000000000000
Null Pointer Exception: Not enough data this time through
This should be a timestamp: 2556dfb
Binary in String: 1001010101111111110000000000000
Null Pointer Exception: Not enough data this time through
This should be a timestamp: 2556f8e
Binary in String: 1001010101101111110000000000000
Null Pointer Exception: Not enough data this time through
This should be a timestamp: 25570da
Binary in String: 1001010101111111110000000000000
Null Pointer Exception: Not enough data this time through
This should be a timestamp: 2557225
Binary in String: 1001010101111011110000000000000
Null Pointer Exception: Not enough data this time through
This should be a timestamp: 255739e
Binary in String: 1001010101111111110000000000000
Null Pointer Exception: Not enough data this time through
This should be a timestamp: 255765a
Binary in String: 1001010101111111010000000000000
Null Pointer Exception: Not enough data this time through
This should be a timestamp: 2557844
Binary in String: 1001010101111110010000000000000
Null Pointer Exception: Not enough data this time through
Can you please break the statements as shown below, if possible please post your complete code. at least the db part.
To write it in a simplified manner. its easier to debug in your case.
Connection con=DriverManager.getConnection(DB_URL,USER,PASS);
String sql = "Your Query";
PreparedStatement ps= conn.prepareStatement(sql);
ps.setXXX;--> binding values
ps.setXXX;
Related
I have a TransferReader class which reads a file containing transfer data from bank account to another using the following form:
SenderAccountID,ReceiverAccountID,Amount,TransferDate
"473728292,474728298,1500.00,2019-10-17 12:34:12" (unmodified string)
Suppose that the file has been modified before being read so that one of the above mentioned paramaters are missing, and I want to check which of those are missing.
"474728298,1500.00,2019-10-17 12:34:12" (modified string)
I am using a BufferedReader to read each line, and then splitting each element into a String[] using String.split(",") as delimeter.
As already realized, because the Sender Account ID and Receiver Account ID are right next to one another within a record there is no real way of knowing which ID might be missing unless a delimiter remains in its' place indicating a Null value. There are however mechanisms available to determine that it is indeed one of the two that is missing, which one will need to be carried out through User scrutiny and even then, that may not be good enough. The other record column fields like Amount and Transfer Date can be easily validated or if missing can be implicated within a specific File Data Status Log.
Below is some code that will read a data file (named Data.csv) and log potential data line (record) errors into a List Interface object which is iterated through and displayed within the Console Window when the read is complete. There are also some small helper methods. Here is the code:
private void checkDataFile(String filePath) {
String ls = System.lineSeparator();
List<String> validationFailures = new ArrayList<>();
StringBuilder sb = new StringBuilder();
// 'Try With Resources' used here to auto-close reader.
try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {
String line;
int lineCount = 0;
// Read the file line-by-line.
while ((line = reader.readLine()) != null) {
line = line.trim();
lineCount++;
if (lineCount == 1 || line.equals("")) {
continue;
}
sb.delete(0, sb.capacity()); // Clear the StringBuilder object
// Start the Status Log
sb.append("File Line Number: ").append(lineCount)
.append(" (\"").append(line).append("\")").append(ls);
// Split line into an Array based on a comma delimiter
// reguardless of the delimiter's spacing situation.
String[] lineParts = line.split("\\s{0,},\\s{0,}");
/* Validate each file line. Log any line that fails
any validation for any record column data into a
List Interface object named: validationFailures
*/
// Are there 4 Columns of data in each line...
if (lineParts.length < 4) {
sb.append("\t- Invalid Column Count!").append(ls);
// Which column is missing...
// *** You may need to add more conditions to suit your needs. ***
if (checkAccountIDs(lineParts[0]) && lineParts.length >= 2 && !checkAccountIDs(lineParts[1])) {
sb.append("\t- Either the 'Sender Account ID' or the "
+ "'ReceiverAccountID' is missing!").append(ls);
}
else if (lineParts.length >= 3 && !checkAmount(lineParts[2])) {
sb.append("\t- The 'Amount' value is missing!").append(ls);
}
else if (lineParts.length < 4) {
sb.append("\t- The 'Transfer Date' is missing!").append(ls);
}
}
else {
// Is SenderAccountID data valid...
if (!checkAccountIDs(lineParts[0])) {
sb.append("\t- Invalid Sender Account ID in column 1! (")
.append(lineParts[0].equals("") ? "Null" :
lineParts[0]).append(")");
if (lineParts[0].length() < 9) {
sb.append(" <-- Not Enough Or No Digits!").append(ls);
}
else if (lineParts[0].length() > 9) {
sb.append(" <-- Too Many Digits!").append(ls);
}
else {
sb.append(" <-- Not All Digits!").append(ls);
}
}
// Is ReceiverAccountID data valid...
if (!checkAccountIDs(lineParts[1])) {
sb.append("\t- Invalid Receiver Account ID in coloun 2! (")
.append(lineParts[1].equals("") ? "Null" :
lineParts[1]).append(")");
if (lineParts[1].length() < 9) {
sb.append(" <-- Not Enough Or No Digits!").append(ls);
}
else if (lineParts[1].length() > 9) {
sb.append(" <-- Too Many Digits!").append(ls);
}
else {
sb.append(" <-- Not All Digits!").append(ls);
}
}
// Is Amount data valid...
if (!checkAmount(lineParts[2])) {
sb.append("\t- Invalid Amount Value in column 3! (")
.append(lineParts[2].equals("") ? "Null" :
lineParts[2]).append(")").append(ls);
}
// Is TransferDate data valid...
if (!checkTransferDate(lineParts[3], "yyyy-MM-dd HH:mm:ss")) {
sb.append("\t- Invalid Transfer Date Timestamp in column 4! (")
.append(lineParts[3].equals("") ? "Null" :
lineParts[3]).append(")").append(ls);
}
}
if (!sb.toString().equals("")) {
validationFailures.add(sb.toString());
}
}
}
catch (FileNotFoundException ex) {
System.err.println(ex.getMessage());
}
catch (IOException ex) {
System.err.println(ex.getMessage());
}
// Display the Log...
String timeStamp = new SimpleDateFormat("yyyy/MM/dd - hh:mm:ssa").
format(new Timestamp(System.currentTimeMillis()));
String dispTitle = "File Data Status at " + timeStamp.toLowerCase()
+ " <:-:> (" + filePath + "):";
System.out.println(dispTitle + ls + String.join("",
Collections.nCopies(dispTitle.length(), "=")) + ls);
if (validationFailures.size() > 0) {
for (String str : validationFailures) {
if (str.split(ls).length > 1) {
System.out.println(str);
System.out.println(String.join("", Collections.nCopies(80, "-")) + ls);
}
}
}
else {
System.out.println("No Issues Detected!" + ls);
}
}
private boolean checkAccountIDs(String accountID) {
return (accountID.matches("\\d+") && accountID.length() == 9);
}
private boolean checkAmount(String amount) {
return amount.matches("-?\\d+(\\.\\d+)?");
}
private boolean checkTransferDate(String transferDate, String format) {
return isValidDateString(transferDate, format);
}
private boolean isValidDateString(String dateToValidate, String dateFromat) {
if (dateToValidate == null || dateToValidate.equals("")) {
return false;
}
SimpleDateFormat sdf = new SimpleDateFormat(dateFromat);
sdf.setLenient(false);
try {
// If not valid, it will throw a ParseException
Date date = sdf.parse(dateToValidate);
return true;
}
catch (ParseException e) {
return false;
}
}
I'm not exactly sure what your particular application process will ultimately entail but if other processes are accessing the file and making modifications to it then it may be wise utilize a locking mechanism to Lock the file during your particular process and Unlock the file when it is done. This however will most likely require you to utilize a different reading algorithm since locking a file must be done through a writable channel. Using the FileChannel and FileLock classes from the java.nio package could possibly assist you here. There would be examples of how to utilize these classes within the StackOverflow forum.
I have a GUI-based application that takes in a file and displays it to the user in a table format, gets some input in the form of column annotations and a bunch of parameters. Then it parses the file accordingly and initiates an "analysis".
I just found a deadlock, one I have not encountered before.
Found one Java-level deadlock:
=============================
"RMI TCP Connection(5)-130.235.214.23":
waiting to lock monitor 0x00007fac650875e8 (object 0x0000000793267298, a java.util.logging.ConsoleHandler),
which is held by "AWT-EventQueue-0"
"AWT-EventQueue-0":
waiting to lock monitor 0x00007fac65086b98 (object 0x00000006c00dd8d0, a java.io.PrintStream),
which is held by "SwingWorker-pool-1-thread-3"
"SwingWorker-pool-1-thread-3":
waiting to lock monitor 0x00007fac65087538 (object 0x00000006c001db48, a java.awt.Component$AWTTreeLock),
which is held by "AWT-EventQueue-0"
Essentially there is a parsing error and trying to log it hangs the application altogether. Interestingly logging appears to work normally before and after that particular step..
Here's the part of the code that's relevant for the analysis task:
// Activate progress indicator
frame.getMainFrame().activateInfiGlass();
SwingWorker<Map<Analyte,AnalysisResult>, Void> worker = new SwingWorker<Map<Analyte,AnalysisResult>, Void>() {
#Override
protected Map<Analyte,AnalysisResult> doInBackground() {
try {
// register parameters
param.addParam(AnalysisParams.value_key,descPanel.getValueTypeComboIndex());
param.addParam(AnalysisParams.sepchar_key,descPanel.getSepCharComboIndex());
paramPanel.registerParams();
StringBuilder sb = new StringBuilder("Data preview completed, initiating analysis...");
sb.append(System.lineSeparator())
.append("... column annotations: ")
.append(Arrays.toString(annots));
logger.info(sb.toString() + System.lineSeparator());
// Create dataset; to be passed on to SwingWorker which will
// execute the analysis
ds = new Dataset();
String[] line;
for (int i=0; i < data.length; i++){
line = data[i];
// If ignore button is clicked, skip row..
if(!(Boolean) table.getValueAt(i, 0))
ds.addRow(line, annots); // <-- This step is where the parsing exception occurs
}
System.out.println("Dataset parsed...");
logger.info("Dataset parsing complete "
+ System.lineSeparator()
+ ds.toString()
+ System.lineSeparator());
visualizeDataset();
conserv = new ConcurrencyService(ds, dbMan);
conserv.serve();
} catch (InterruptedException e) {
logger.severe("Concurrency service interrupted"
+ System.lineSeparator()
+ DebugToolbox.getStackTraceAsString(e)
+ System.lineSeparator());
System.err.println("Interrupt exception!!");
}
return conserv.getAnalyzedPaths();
}
#Override
protected void done() {
try{
results = get();
visualizeResults();
}
catch (InterruptedException ignore) {}
catch (java.util.concurrent.ExecutionException e) {
String why = null;
Throwable cause = e.getCause();
if (cause != null) {
why = cause.getMessage();
} else {
why = e.getMessage();
}
System.err.println("Error analysing data: " + why);
} catch (SQLException e) {
e.printStackTrace();
}
logger.info("#DEBUG: Conserv should have been terminated by now..." + System.lineSeparator());
frame.getMainFrame().deactivateInfiGlass();
DebugToolbox.stopExecTimer();
}
};
worker.execute();
}});
The parsing of the values happens in an instance of Dataset, using method addRow(). The following piece of code shows the way the parsing error is handled
public double valueToIntensity(String val){
if(val.equalsIgnoreCase(""))
return missingVal;
try{
double d = Double.parseDouble(val);
switch(valType){
case RAW: break;
case LOG2: d = StrictMath.pow(2,d); break;
case LOGN: d = StrictMath.pow(StrictMath.E, d); break;
case LOG10: d = StrictMath.pow(10,d); break;
default: throw new RuntimeException("Unrecognized value type");
}
if(Double.isInfinite(d)){
StringBuilder msg = new StringBuilder("Double precision overflow occurred: 'd' is infinite!!");
msg.append(System.lineSeparator())
.append("chosen value scale is ").append(valType)
.append(System.lineSeparator())
.append("value = ").append(val);
logger.severe(msg.toString() + System.lineSeparator());
System.err.println("Data parsing error!!" +
"Please make sure that you have selected the correct scale...");
System.exit(FeverMainFrame.exitCodes.get(this.getClass()));
}
else
return d;
} catch (NumberFormatException e){
System.err.println("Data parsing error!!");
// THE FOLLOWING LINE IS WHERE DEADLOCK OCCURS
logger.severe("Expected: string representation of a numerical value, "
+ "Found: " + val + System.lineSeparator());
System.err.println("Please make sure the datafile does not include any strings "
+ "like 'N/A' or '-' for denoting missing values.");
System.exit(FeverMainFrame.exitCodes.get(this.getClass()));
}
// TODO: This should never happen!
throw new RuntimeException("Assertion failed during dataset parsing...");
}
If I remove the values that are causing the parsing error, without changing anything else, both the logging framework and the rest of application runs as expected.
I would really appreciate any insight as to what is going on in this particular case.
Absent a complete example, verify that your implementation of doInBackground() does not attempt to update any GUI component or model. Instead, publish() interim results and process() them on the EDT as they become available. A complete example is shown here.
I am getting too many deadlocks on OrientDb while I am using Java API to query the vertices. After the deadlock happens, the entire database becomes unresponsive and I have to kill the daemon and start again. As example, the error that I get from deadlocks is :
com.orientechnologies.common.concur.OTimeoutException: Can not lock record for 2000 ms. seems record is deadlocked by other record
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.acquireReadLock(OAbstractPaginatedStorage.java:1300)
at com.orientechnologies.orient.core.tx.OTransactionAbstract.lockRecord(OTransactionAbstract.java:120)
at com.orientechnologies.orient.core.id.ORecordId.lock(ORecordId.java:282)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.lockRecord(OAbstractPaginatedStorage.java:1776)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.readRecord(OAbstractPaginatedStorage.java:1416)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.readRecord(OAbstractPaginatedStorage.java:694)
at com.orientechnologies.orient.core.db.document.ODatabaseDocumentTx.executeReadRecord(ODatabaseDocumentTx.java:1569)
at com.orientechnologies.orient.core.tx.OTransactionNoTx.loadRecord(OTransactionNoTx.java:80)
at com.orientechnologies.orient.core.db.document.ODatabaseDocumentTx.load(ODatabaseDocumentTx.java:1434)
at com.orientechnologies.orient.server.network.protocol.binary.ONetworkProtocolBinary.readRecord(ONetworkProtocolBinary.java:1456)
at com.orientechnologies.orient.server.network.protocol.binary.ONetworkProtocolBinary.executeRequest(ONetworkProtocolBinary.java:346)
at com.orientechnologies.orient.server.network.protocol.binary.OBinaryNetworkProtocolAbstract.execute(OBinaryNetworkProtocolAbstract.java:216)
at com.orientechnologies.common.thread.OSoftThread.run(OSoftThread.java:65)
Following is the block that I use to query edges and create associations between vertices
public User generateFriend(String mobile, String userRID) {
StringBuilder errorMsg = new StringBuilder();
Iterable<OrientVertex> vertexes;
//Retrieve friends of the user
List<User> friendsList = new ArrayList<User>();
vertexes = db.queryVertices("select expand( unionAll(inE('E_Friend').out,outE('E_Friend').in) ) from " + userRID,errorMsg);
if (!errorMsg.toString().equals("")) {
throw new DbException("Db exception occured, " + errorMsg);
}
for (OrientVertex v : vertexes){
friendsList.add(vertexToUser(v));
}
//Create edges if between the user and other users with mobile number in the list and if the edge is not yet created
User u = findUserByMobileNo(friendsList,mobile);
if ( u == null){
u = findByMobileNo(mobile);
if (u != null) {
//create edge
db.executeQuery("select createEdge('E_Friend','" + userRID + "','" + u.getRid() + "') from " + userRID, new HashMap<String, Object>(), errorMsg);
if (!errorMsg.toString().equals("")) {
throw new DbException("Db exception occured, " + errorMsg);
}
}
}
return u;
}
public Iterable<OrientVertex> queryVertices(String query, StringBuilder errMsg){
logger.error("before getGraph, " + errMsg.toString());
graph = getGraph(errMsg);
if (!errMsg.toString().equals("")){
return null;
}
logger.error("after getGraph, " + errMsg.toString());
Iterable<OrientVertex> vertices = null;
try {
OSQLSynchQuery<OrientVertex> qr = new OSQLSynchQuery<OrientVertex>(query);
vertices = graph.command(qr).execute();
logger.error("after graph command execute, " + errMsg.toString());
}
catch (Exception ex){
errMsg.append(ex.getMessage());
logger.error("graph command exception, " + errMsg.toString());
}
logger.error("before return vertices, " + errMsg.toString());
return vertices;
}
public List<ODocument> executeQuery(String sql, HashMap<String,Object> params,StringBuilder errMsg) {
List<ODocument> result = new ArrayList<ODocument>();
try {
db = getDatabase(errMsg);
if (!errMsg.toString().equals("")){
return null;
}
OSQLSynchQuery<ODocument> query = new OSQLSynchQuery<ODocument>(sql);
if (params.isEmpty()) {
result = db.command(query).execute();
} else {
result = db.command(query).execute(params);
}
} catch (Exception e) {
errMsg.append(e.getMessage());
//TODO: Add threaded error log saving mechanism
}
return result;
}
Due to index missing on table deadlock come, so check your all table which are involved in this operation and find out that indexes are present or not on column.
Refer link in which I have a same problem of deadlock.
I have a piece of JAVA code that is accessed by multiple threads.
synchronized (this.getClass())
{
System.out.println("stsrt");
certRequest.setRequestNbr(
generateRequestNumber(
certInsuranceRequestAddRq.getAccountInfo().getAccountNumberId()));
System.out.println("outside funcvtion"+certRequest.getRequestNbr());
reqId = Utils.getUniqueId();
certRequest.setRequestId(reqId);
System.out.println(reqId);
ItemIdInfo itemIdInfo = new ItemIdInfo();
itemIdInfo.setInsurerId(certRequest.getRequestId());
certRequest.setItemIdInfo(itemIdInfo);
dao.insert(certRequest);
addAccountRel();
System.out.println("end");
}
the function generateRequestNumber() generates a request number based on the data fetched from two database tables.
public String generateRequestNumber(String accNumber) throws Exception
{
String requestNumber = null;
if (accNumber != null)
{
String SQL_QUERY = "select CERTREQUEST.requestNbr from CertRequest as CERTREQUEST, "
+ "CertActObjRel as certActObjRel where certActObjRel.certificateObjkeyId=CERTREQUEST.requestId "
+ " and certActObjRel.certObjTypeCd=:certObjTypeCd "
+ " and certActObjRel.certAccountId=:accNumber ";
String[] parameterNames = { "certObjTypeCd", "accNumber" };
Object[] parameterVaues = new Object[]
{
Constants.REQUEST_RELATION_CODE, accNumber
};
List<?> resultSet = dao.executeNamedQuery(SQL_QUERY,
parameterNames, parameterVaues);
// List<?> resultSet = dao.retrieveTableData(SQL_QUERY);
if (resultSet != null && resultSet.size() > 0) {
requestNumber = (String) resultSet.get(0);
}
int maxRequestNumber = -1;
if (requestNumber != null && requestNumber.length() > 0) {
maxRequestNumber = maxValue(resultSet.toArray());
requestNumber = Integer.toString(maxRequestNumber + 1);
} else {
requestNumber = Integer.toString(1);
}
System.out.println("inside function request number"+requestNumber);
return requestNumber;
}
return null;
}
The tables CertRequest and CertActObjRel used in generateRequestNumber() are updated by the functions "dao.insert(certRequest);" and "addAccountRel();" used in my initial code respectively. Also the System.out.println() statements used in my initial code have following output.
stsrt
inside function request number73
outside funcvtion73
A1664886-5F84-45A9-AB5F-C69768B83EAD
end
stsrt
inside function request number73
outside funcvtion73
44DAD872-6A1D-4524-8A32-15741FAC0CA9
end
If you notice both the threads run in a synchronized manner, but when the request number is generated , it's the same. My assumption is the database updation for CertRequest and CertActObjRel is done when both the threads finish their execution.
Could anyone help me to fix this?
I am working with Jackcess to read and categorize an access database. It's simply meant to open the database, loop through each line, and print out individual row data to the console which meet certain conditions. It works fine, except for when I try to read numeric values. My code is below. (This code is built into a Swing GUI and gets executed when a jbutton is pressed.)
if (inv == null) { // Check to see if inventory file has been set. If not, then set it to the default reference path.
inv = rPath;
}
if (inventoryFile.exists()) { // Check to see if the reference path exists.
List<String> testTypes = jList1.getSelectedValuesList();
List<String> evalTypes = jList3.getSelectedValuesList();
List<String> grainTypes = jList2.getSelectedValuesList();
StringBuilder sb = new StringBuilder();
for (int i=0; i<=evalTypes.size()-1; i++) {
if (i<evalTypes.size()-1) {
sb.append(evalTypes.get(i)).append(" ");
}
else {
sb.append(evalTypes.get(i));
}
}
String evalType = sb.toString();
try (Database db = DatabaseBuilder.open(new File(inv));) {
Table sampleList = db.getTable("NTEP SAMPLES LIST");
Cursor cursor = CursorBuilder.createCursor(sampleList);
for (int i=0; i<=testTypes.size()-1; i++) {
if ("Sample Volume".equals(testTypes.get(i))) {
if (grainTypes.size() == 1 && "HRW".equals(grainTypes.get(0))) {
switch (evalType) {
case "GMM":
for (Row row : sampleList){
if (null != row.getString("CURRENTGAC")) {}
if ("HRW".equals(row.get("GRAIN")) && row.getDouble("CURRENTGAC")>=12.00) {
System.out.print(row.get("GRAIN") + "\t");
System.out.println(row.get("CURRENTGAC"));
}
}
break;
case "NIRT":
// some conditional code
break;
case "TW":
// some more code
break;
}
}
else {
JOptionPane.showMessageDialog(null, "Only HRW samples can be used for the selected test(s).", "Error", JOptionPane.ERROR_MESSAGE);
}
break;
}
}
}
catch (IOException ex) {
Logger.getLogger(SampleFilterGUI.class.getName()).log(Level.SEVERE, null, ex);
}
When the code is run I get the following error:
java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
The following condition looks to be what is throwing the error.
row.getDouble("CURRENTGAC")>=12.00
It appears that when the data is read from the database, the program is reading everything as a string, even though some fields are numeric. I was attempting to cast this field as a double, but java doesn't seem to like that. I have tried using the Double.parseDouble() and Double.valueOf() commands to try converting the value (as mentioned here) but without success.
My question is, how can I convert these fields to numeric values? Is trying to type cast the way to go, or is there a different method I'm not aware of? You will also notice in the code that I created a cursor, but am not using it. The original plan was to use it for navigating through the database, but I found some example code from the jackcess webpage and decided to use that instead. Not sure if that was the right move or not, but it seemed like a simpler solution. Any help is much appreciated. Thanks.
EDIT:
To ensure the program was reading a string value from my database, I input the following code
row.get("CURRENTGAC").getClass().getName()
The output was java.lang.String, so this confirms that it is a string. As was suggested, I changed the following code
case "GMM":
for (Row row : sampleList){
if (null != row.get("CURRENTGAC"))
//System.out.println(row.get("CURRENTGAC").getClass().getName());
System.out.println(String.format("|%s|", row.getString("CURRENTGAC")));
/*if ("HRW".equals(row.get("GRAIN")) && row.getDouble("CURRENTGAC")>=12.00 && row.getDouble("CURRENTGAC")<=14.00) {
System.out.print(row.get("GRAIN") + "\t");
System.out.println(row.get("CURRENTGAC"));
}*/
}
break;
The ouput to the console from these changes is below
|9.85|
|11.76|
|9.57|
|12.98|
|10.43|
|13.08|
|10.53|
|11.46|
...
This output, although looks numeric, is still of the string type. So when I tried to run it with my conditional statement (which is commented out in the updated sample code) I still get the same java.lang.ClassCastException error that I was getting before.
Jackcess does not return all values as strings. It will retrieve the fields (columns) of a table as the appropriate Java type for that Access field type. For example, with a test table named "Table1" ...
ID DoubleField TextField
-- ----------- ---------
1 1.23 4.56
... the following Java code ...
Table t = db.getTable("Table1");
for (Row r : t) {
Object o;
Double d;
String fieldName;
fieldName = "DoubleField";
o = r.get(fieldName);
System.out.println(String.format(
"%s comes back as: %s",
fieldName,
o.getClass().getName()));
System.out.println(String.format(
"Value: %f",
o));
System.out.println();
fieldName = "TextField";
o = r.get(fieldName);
System.out.println(String.format(
"%s comes back as: %s",
fieldName,
o.getClass().getName()));
System.out.println(String.format(
"Value: %s",
o));
try {
d = r.getDouble(fieldName);
} catch (Exception x) {
System.out.println(String.format(
"r.getDouble(\"%s\") failed - %s: %s",
fieldName,
x.getClass().getName(),
x.getMessage()));
}
try {
d = Double.parseDouble(r.getString(fieldName));
System.out.println(String.format(
"Double.parseDouble(r.getString(\"%s\")) succeeded. Value: %f",
fieldName,
d));
} catch (Exception x) {
System.out.println(String.format(
"Double.parseDouble(r.getString(\"%s\")) failed: %s",
fieldName,
x.getClass().getName()));
}
System.out.println();
}
... produces:
DoubleField comes back as: java.lang.Double
Value: 1.230000
TextField comes back as: java.lang.String
Value: 4.56
r.getDouble("TextField") failed - java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
Double.parseDouble(r.getString("TextField")) succeeded. Value: 4.560000
If you are unable to get Double.parseDouble() to parse the string values from your database then either
they contain "funny characters" that are not apparent from the samples you posted, or
you're doing it wrong.
Additional information re: your sample file
Jackcess is returning CURRENTGAC as String because it is a Text field in the table:
The following Java code ...
Table t = db.getTable("NTEP SAMPLES LIST");
int countNotNull = 0;
int countAtLeast12 = 0;
for (Row r : t) {
String s = r.getString("CURRENTGAC");
if (s != null) {
countNotNull++;
Double d = Double.parseDouble(s);
if (d >= 12.00) {
countAtLeast12++;
}
}
}
System.out.println(String.format(
"Scan complete. Found %d non-null CURRENTGAC values, %d of which were >= 12.00.",
countNotNull,
countAtLeast12));
... produces ...
Scan complete. Found 100 non-null CURRENTGAC values, 62 of which were >= 12.00.