I have the following Android code:
public final List<MyObj> getList() {
Cursor cursor = null;
try {
final String queryStr = GET_LIST_STATEMENT;
cursor = db.rawQuery(queryStr, new String[] {});
List<MyObj> list = null;
//here I get the data from de cursor.
return list ;
} catch (SQLiteFullException ex) {
//do something to treat the exception.
} finally {
if (cursor != null) {
cursor.close();
}
}
}
When I run PMD analysis over this code, I get the following issue: Found 'DD'-anomaly for variable 'cursor' (lines '182'-'185').
The line 182 is: Cursor cursor = null;.
The line 185 is: cursor = db.rawQuery(queryStr, new String[] {});
So, I understand that the problem is that I'm doing a Premature Initialization in the line 182 (I never read the variable between the lines 182 and 185), but if I don't do that, I can't have the code closing the cursor in the finally block.
What to do in this case? Just ignore this PMD issue? Can I configure PMD to don't rise up this specific kind of DD-anomaly (not all DD-anomaly)? Should PMD be smart enough to doesn't rise up this issue?
Another example of DD-anomaly that I think is not a real problem:
Date distributeDate;
try {
distributeDate = mDf.parse(someStringDate);
} catch (ParseException e) {
Log.e("Problem", "Problem parsing the date of the education. Apply default date.");
distributeDate = Calendar.getInstance().getTime();
}
In this case, the anomaly occurs with the distributeDate variable.
The documentation is pretty easy to understand:
Either you use annotations to suppress warnings:
// This will suppress UnusedLocalVariable warnings in this class
#SuppressWarnings("PMD.UnusedLocalVariable")
public class Bar {
void bar() {
int foo;
}
}
or you use a comment:
public class Bar {
// 'bar' is accessed by a native method, so we want to suppress warnings for it
private int bar; //NOPMD
}
When it comes to your specific code, I'd say that the easiest way to handle it is to not use a finally block even though this would look like the perfect place for it.
Related
We have to implement a logic to write the unique code generation in Java. The concept is when we generate the code the system will check if the code is already generate or not. If already generate the system create new code and check again. But this logic fails in some case and we cannot able to identify what is the issue is
Here is the code to create the unique code
Integer code = null;
try {
int max = 999999;
int min = 100000;
code = (int) Math.round(Math.random() * (max - min + 1) + min);
PreOrders preObj = null;
preObj = WebServiceDao.getInstance().preOrderObj(code.toString());
if (preObj != null) {
createCode();
}
} catch (Exception e) {
exceptionCaught();
e.printStackTrace();
log.error("Exception in method createCode() - " + e.toString());
}
return code;
}
The function preOrderObj is calling a function to check the code exists in the database if exists return the object. We are using Hibernate to map the database functions and Mysql on the backend.
Here is the function preOrderObj
PreOrders preOrderObj = null;
List<PreOrders> preOrderList = null;
SessionFactory sessionFactory =
(SessionFactory) ServletActionContext.getServletContext().getAttribute(HibernateListener.KEY_NAME);
Session Hibernatesession = sessionFactory.openSession();
try {
Hibernatesession.beginTransaction();
preOrderList = Hibernatesession.createCriteria(PreOrders.class).add(Restrictions.eq("code", code)).list(); // removed .add(Restrictions.eq("status", true))
if (!preOrderList.isEmpty()) {
preOrderObj = (PreOrders) preOrderList.iterator().next();
}
Hibernatesession.getTransaction().commit();
Hibernatesession.flush();
} catch (Exception e) {
Hibernatesession.getTransaction().rollback();
log.debug("This is my debug message.");
log.info("This is my info message.");
log.warn("This is my warn message.");
log.error("This is my error message.");
log.fatal("Fatal error " + e.getStackTrace().toString());
} finally {
Hibernatesession.close();
}
return preOrderObj;
}
Please guide us to identify the issue.
In createCode method, when the random code generated already exist in database, you try to call createCode again. However, the return value from the recursive call is not updated to the code variable, hence the colliding code is still returned and cause error.
To fix the problem, update the method as
...
if (preObj != null) {
//createCode();
code = createCode();
}
...
Such that the code is updated.
By the way, using random number to generate unique value and test uniqueness through query is a bit strange. You may try Auto Increment if you want unique value.
What Happened
All the data from last month was corrupted due to a bug in the system. So we have to delete and re-input these records manually. Basically, I want to delete all the rows inserted during a certain period of time. However, I found it difficult to scan and delete millions of rows in HBase.
Possible Solutions
I found two way to bulk delete:
The first one is to set a TTL, so that all the outdated record would be deleted automatically by the system. But I want to keep the records inserted before last month, so this solution does not work for me.
The second option is to write a client using the Java API:
public static void deleteTimeRange(String tableName, Long minTime, Long maxTime) {
Table table = null;
Connection connection = null;
try {
Scan scan = new Scan();
scan.setTimeRange(minTime, maxTime);
connection = HBaseOperator.getHbaseConnection();
table = connection.getTable(TableName.valueOf(tableName));
ResultScanner rs = table.getScanner(scan);
List<Delete> list = getDeleteList(rs);
if (list.size() > 0) {
table.delete(list);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (null != table) {
try {
table.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (connection != null) {
try {
connection.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
private static List<Delete> getDeleteList(ResultScanner rs) {
List<Delete> list = new ArrayList<>();
try {
for (Result r : rs) {
Delete d = new Delete(r.getRow());
list.add(d);
}
} finally {
rs.close();
}
return list;
}
But in this approach, all the records are stored in ResultScanner rs, so the heap size would be huge. And if the program crushes, it has to start from the beginning.
So, is there a better way to achieve the goal?
Don't know how many 'millions' you are dealing with in your table, but the simples thing is to not try to put them all into a List at once but to do it in more manageable steps by using the .next(n) function. Something like this:
for (Result row : rs.next(numRows))
{
Delete del = new Delete(row.getRow());
...
}
This way, you can control how many rows get returned from the server via a single RPC through the numRows parameter. Make sure it's large enough so as not to make too many round-trips to the server, but at the same time not too large to kill your heap. You can also use the BufferedMutator to operate on multiple Deletes at once.
Hope this helps.
I would suggest two improvements:
Use BufferedMutator to batch your deletes, it does exactly what you need – keeps internal buffer of mutations and flushes it to HBase when buffer fills up, so you do not have to worry about keeping your own list, sizing and flushing it.
Improve your scan:
Use KeyOnlyFilter – since you do not need the values, no need to retrieve them
use scan.setCacheBlocks(false) - since you do a full-table scan, caching all blocks on the region server does not make much sense
tune scan.setCaching(N) and scan.setBatch(N) – the N will depend on the size of your keys, you should keep a balance between caching more and memory it will require; but since you only transfer keys, the N could be quite large, I suppose.
Here's an updated version of your code:
public static void deleteTimeRange(String tableName, Long minTime, Long maxTime) {
try (Connection connection = HBaseOperator.getHbaseConnection();
final Table table = connection.getTable(TableName.valueOf(tableName));
final BufferedMutator mutator = connection.getBufferedMutator(TableName.valueOf(tableName))) {
Scan scan = new Scan();
scan.setTimeRange(minTime, maxTime);
scan.setFilter(new KeyOnlyFilter());
scan.setCaching(1000);
scan.setBatch(1000);
scan.setCacheBlocks(false);
try (ResultScanner rs = table.getScanner(scan)) {
for (Result result : rs) {
mutator.mutate(new Delete(result.getRow()));
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
Note the use of "try with resource" – if you omit that, make sure to .close() mutator, rs, table, and connection.
I am using below code,i have checked pathname and sheet name is all fine.
I am using fillo version fillo-1.15.
public class T_Test {
public static void main(String[] args) throws Exception{
try {
com.codoid.products.fillo.Fillo fil_res = new com.codoid.products.fillo.Fillo();
com.codoid.products.fillo.Connection con_res = fil_res
.getConnection("C:\\Users\\admin\\workspace\\Good Connect\\Test_Data/Result\\LifePlanner_Result.xlsx");
String sql_res = "update Result_Data SET Product_ID = 'Sampoorna Raksha' Where TestCase_ID = 'TC1_SIS' ";
System.out.println(sql_res);
com.codoid.products.fillo.Recordset recordset_rec = con_res.executeQuery(sql_res);
con_res.close();
} catch (Exception e) {
System.out.println("Exception result set:" + e.toString());
}
}
}
Error is below:
java.lang.NullPointerException
Exception result set:java.lang.NullPointerException
at com.codoid.products.parser.SelectQueryParser.isWherePresent(SelectQueryParser.java:66)
at com.codoid.products.fillo.Select.getRecordset(Select.java:47)
at com.codoid.products.fillo.Connection.executeQuery(Connection.java:56)
at GoodSolutionAgence.T_Test.main(T_Test.java:89)
I believe the error is here:
com.codoid.products.fillo.Recordset recordset_rec = con_res.executeQuery(sql_res);
You are executing an UPDATE statement, not a SELECT query. An UPDATE statement won't return a record set, just the number of rows it updated. You therefore want to use executeUpdate in place of executeQuery:
int numberOfRowsUpdated = con_res.executeUpdate(sql_res);
However, the Fillo library could at least have warned you that you were using the wrong method. The fact that it threw a NullPointerException is in my opinion a bug in this library: it should handle this error condition better.
Null Pointer Exception occurs when you try to reference a variable that has not been initialized
com.codoid.products.fillo.Connection con_res = fil_res
.getConnection("C:\\Users\\admin\\workspace\\Good Connect\\Test_Data/Result\\LifePlanner_Result.xlsx");
In this case the con_res might be null since getConnection method is not functioning properly.
Now when you try to execute
con_res.executeQuery(sql_res);
It results in Null Pointer Exception.
Check whether con_res gets initialized properly and check the path specified in getConnection method
i want to put if else or switch statement which is more suitable for checking employee count before commit.where i put my if else or switch code . i want restriction on employee if count is 5 then its show message "reached maximum employee limites" otherwise allow commit.
i am new in java plz someone help me to solve this
public String cmdSave_action()
{
// my code before
{
DeptSet result;
try {
dbo.connect();
result =
dbo.execSQL("select count(*) from empmasterinfo where mainid='ORGElement' and designationid='?') "
(inputText_ORGElement.getValue() != null ?
""));
result = dbo.execSQL(sSQL);
catch (Exception e) {
System.out.println(e.getMessage());
finally
{
dbo.close();
}
return null;
}}}
// my code above
{
Global.PerformIteratorAction(this.bindings, "Commit");
AdfFacesContext afContext = AdfFacesContext.getCurrentInstance();
afContext.getProcessScope().put("EmployeeID",
Global.getCurrRowFieldValue("EmpmasterinfoViewIterator",
"Employeeid"));
if (afContext.getProcessScope().get("AddEdit").toString().equals("0"))
{
Global.PerformIteratorAction(this.bindings,
"EPR_TRANSFER_APPLICANT_INFO");
Global.PerformIteratorAction(this.bindings, "eprGenerateApPlan");
}
return null;
}}
My Error Log
Error(149,12): 'try' without 'catch' or 'finally'
Error(154,36): , expected
Error(157,34): field SQL not found in class hcm.view.backing.empprofile.EmployeeMasterInfo_Add
Error(159,11): illegal start of expression
Error(159,11): ; expected
E:\HCM\ViewController\src\hcm\view\backing\empprofile\dbo.java
Error(13,16): method does not return a value
Please close Your try catch block properly
try{
}catch(Exception e){
}finally{
}
And Read this
catch and finally are within try block
try {
//code
}
catch(Exception e) {
System.out.println(e.getMessage());
}
finally {
dbo.close();
}
Using an IDE will help you with indentation and proper formatting while writing code. e.g Eclipse.
For the first error close the try-catch blocks properly
And for the second error: Since your method is declared as public String cmdSave_action(), you should return a String value at the end of the method. The return statement is missing in your code.
I am having a LDAP Queue which process a object class.I cant find the exact location why it is giving the exception. The objclass is a concadenation string with pipe symbol. Any program coding to find the exact location in which concadination part is going to the Exception?.Please Assist.
try {
Attributes objClass = null;
try {
objClass = getObjClass(LdapInfo.PER_ID, person.perId);
} catch (NamingException e)
{
DCXError.myInstance().writeError("LdapUpdaterConnection: " + e.getMessage());
}
NamingEnumeration oc = objClass.get("objectclass").getAll();
String baseObjClass = null;
while (oc.hasMoreElements()) {
baseObjClass = (String) oc.nextElement();
if (baseObjClass.equalsIgnoreCase(LdapInfo.NON_EMPLOYEE_PERSON)
|| baseObjClass.equalsIgnoreCase("N/A")||
baseObjClass.equalsIgnoreCase(LdapInfo.EMPLOYEE_PERSON))
break;
}
} catch (SchemaViolationException e4) {
DCXError.myInstance().writeError(
"LdapUpdaterConnection:doUpdate SchemaViolationException "+ e4.getExplanation());
DCXError.myInstance().writeError("LdapUpdaterConnection:update persID = " + personId);
return (LdapUpdaterConnection.BAD_DATA);
}
You can't find the exact location only because you haven't logged the stack trace. You would also need to reformat your code so that each statement is on a separate line to make any use of that information. You should also use variable names that actually correspond to the content.
This is really terrible code.
It's also hard to see why you are doing all this in the first place. A decent query filter would do all that for you far more simply.