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Iterate over multiple list in java

While i am trying to convert below code snippet using java8 getting "Local variable sId defined in an enclosing scope must be final or effectively final" error.
Existing code:
String sId = "";
String uId = "";
FinalResp resp = new FinalResp();
List<LiqResp> liqRespList = getResp.getLiqRespList();
for(LiqResp liqResp : liqRespList){
List<ListOfAcq> listAcq = liqResp.getLiqList();
for(ListOfAcq acqList : listAcq){
List<Acq> acqs = acqList.getAcqList();
for(Acq acq :acqs){
if(sId.equalIgnoreCase(acq.getId()) || uId.equalIgnoreCase(acq.getId())){
resp.setId(acqList.getId());
}
}
}
}
return resp;
Below is the snippet which i tried to convert using java8:
String sId = "";
String uId = "";
FinalResp resp = new FinalResp();
List<LiqResp> liqRespList = getResp.getLiqRespList();
liqRespList.parallelStream.forEach(liqResp -> liqResp.getLiqList().parallelStream.
forEach(acqList->acqList.getAcqList().stream.map(acq -> {
return conversion(acq, acqList, sId,uId,resp); //getting error here as "Local variable sId
//defined in an enclosing scope must be final
// or effectively final"
})));
private FinalResp conversion(Acq acq, ListOfAcq acqList, String sId,String uId,FinalResp resp){
if(sId.equalIgnoreCase(acq.getId()) || uId.equalIgnoreCase(acq.getId())){
resp.setId(acqList.getId());
}
return resp;
}
Performance wise is this correct approach.thanks in advance for help.

Java returning null pointer exception for SQL query that gets passed to JSP

I am working on a school assignment that required us to use SQL statements in Java code as well as use the LIKE operator for a search. In order to properly search I have to get a string from the user, and split the string by any delimiter, and then run the query like so:
SELECT * FROM movies WHERE (movies.title LIKE '%userInput%');
I then return this query in the form of an ArrayList.
Now, when I was testing it out. I originally tested it with no user input, and my query became: SELECT * FROM movies WHERE (movies.title LIKE '%%');. This gave me the correct results.
However when I put a title in there, all of the sudden I get a NullPointerException on this line:
if(title.equals("")) { return "(movies.title LIKE '%%') "; from this section of my code:
public String getSearchString(String title) {
if(title.equals("")) { return "(movies.title LIKE '%%') "; }
String ret = "(";
ArrayList<String> titleArray = Util.splitSearch(title);
for(int i = 0; i < titleArray.size() - 1; ++i) {
String temp = titleArray.get(i);
String stmt = "movies.title LIKE '%" + temp + "%' OR ";
ret += stmt;
}
String temp = "movies.title LIKE '%" + titleArray.get(titleArray.size() - 1) + "%')";
ret += temp;
return ret;
}
This is then called like so:
public List<Movie> listMovies(String title) throws SQLException {
List<Movie> search = new ArrayList<Movie>();
if(null != title && title.isEmpty()) { title = ""; }
ResultSet res = queryMovies(getSearchString(title));
while(res.next()) {
Movie mov = new Movie();
mov.setTitle(res.getString("title"));
search.add(mov);
}
return search;
}
private static queryMovies(String st) throws SQLException {
ResultSet res = null;
try {
PreparedStatement ps = dbcon.prepareStatement(st);
res = ps.executeQuery();
} catch(SQLException e) {
e.printStackTrace();
}
return res;
}
I unfortunately have to do this since I won't know how much a user will enter. And I am also not allowed to use external libraries that make the formatting easier. For reference my Util.splitSearch(...) method looks like this. It should be retrieving anything that is a alphanumeric character and should be splitting on anything that is not alphanumeric:
public static ArrayList<String> splitSearch(String str) {
String[] strArray = str.split("[^a-zA-Z0-9']");
return new ArrayList(Arrays.asList(strArray));
}
What is interesting is when I pass in getSearchString(""); explicitly, I do not get a NullPointerException. It is only when I allows the variable title to be used do I get one. And I still get one when no string is entered.
Am I splitting the String wrong? Am I somehow giving SQL the wrong statement? Any help would be appreciated, as I am very new to this.

the "title" which is passed from input is null, hence you're getting nullpointerexception when you do title.equals("").
Best practices suggest you do a null check like (null != title && title.equals("")).
You can also do "".equals(title)

String cannot be added to List using Object in Java

I am working on a JSF based Web Application where I read contents from a file(dumpfile) and then parse it using a logic and keep adding it to a list using an object and also set a string using the object. But I keep getting this error. I am confused where I am wrong. I am a beginner so can anyone be kind enough to help me?
List<DumpController> FinalDumpNotes;
public List<DumpController> initializeDumpNotes()
throws SocketException, IOException {
PostProcessedDump postProcessedDump = (PostProcessedDump) FacesContext.getCurrentInstance().getExternalContext().getSessionMap().get("postProcessedDump");
List<DumpController> FinalNotes = new ArrayList<>();
if (postProcessedDump.getDumpNotes() == null) {
dumpNotes = new DumpNotes();
}
DumpListController dlcon = (DumpListController) FacesContext.getCurrentInstance().getExternalContext().getSessionMap().get("dumpListController");
DumpInfo dumpinfo = dlcon.getSelectedDumpInfo();
String fileName = dumpinfo.getDate() + dumpinfo.getTime() + dumpinfo.getSeqNo() + dumpinfo.getType() + dumpinfo.getTape() + dumpinfo.getDescription() + ".txt";
if (checkFileExistsInWin(fileName)) {
postProcessedDump.setDumpnotescontent(getFileContentsFromWin(fileName));
String consolidateDumpnotes = getFileContentsFromWin(fileName);
String lines[];
String content = "";
lines = consolidateDumpnotes.split("\\r?\\n");
List<String> finallines = new ArrayList<>();
int k = 0;
for (int i = 0; i < lines.length; i++) {
if (!lines[i].equalsIgnoreCase("")) {
finallines.add(lines[i]);
k++;
}
}
for (int j = 0; j < finallines.size(); j++) {
if (finallines.get(j).startsWith("---------------------SAVED BY")) {
PostProcessedDump dump = new PostProcessedDump();
dump.setDumpMessage(content);
content = "";
FinalDumpNotes.add(dump);
} else {
content = content + finallines.get(j);
}
}
}
FacesContext.getCurrentInstance().getExternalContext().getSessionMap().put("postProcessedDump", postProcessedDump);
return FinalDumpNotes;
}
I get the following error:

If you want to add instances of type PostProcessedDump to your List you should change it's type. Also, don't forget to initialize it. Something like,
List<PostProcessedDump> FinalDumpNotes = new ArrayList<>();
Also, Java naming convention is to start variable names with a lower case letter. FinalDumpNotes looks like a class, I would suggest something like
List<PostProcessedDump> processedList = new ArrayList<>();

Problems with your code:
List<DumpController> FinalDumpNotes;
You declare FinalDumpNotes to be a List of DumpController objects, but you never initialize it. In addition, your IDE is barfing on the following line of code:
FinalDumpNotes.add(dump);
because you are attempting to add a PostProcessedDump object to the List instead of a DumpController object.
For starters, you need to initialize your list like this:
List<DumpController> finalDumpNotes = new ArrayList<DumpController>();
Notice that I have made the variable name beginning with lower case, which is the convention (upper case is normally reserved for classes and interfaces).
I will leave it to you as a homework assignment to sort out the correct usage of this List.

JAVA - How to access variables inside a FOR loop, from outside the for loop

My code is to add RSS feeds to a list - and the code originally was only to pull one feed from the first position in a list, and add this object to another list.
This was the original code:
public static List<Feed> getFeedsFromXml(String xml) {
Pattern feedPattern = Pattern.compile("<feed>\\s*<name>\\s*([^<]*)</name>\\s*<uri>\\s*([^<]*)</uri>\\s*</feed>");
Matcher feedMatch = feedPattern.matcher(xml);
while (feedMatch.find()) {
String feedName = feedMatch.group(1);
String feedURI = feedMatch.group(2);
feeds.add(new Feed(feedName, feedURI));
}
return feeds;
}
#POST
#Consumes(MediaType.APPLICATION_XML)
#Produces(MediaType.APPLICATION_XML)
public String addXmlFeed() throws IOException
{
int i = 0;
String stringXml = "<feed><name>SMH Top Headlines</name><uri>http://feeds.smh.com.au/rssheadlines/top.xml</uri></feed><feed><name>UTS Library News</name>";
getFeedsFromXml(stringXml);
Feed f = (Feed) feeds.get(0);
feedList.add(f);
String handler = "You have successfully added: \n";
String xmlStringReply = "" + f + "\n";
feedList.save(feedFile);
return handler + xmlStringReply;
}
Everything was going well, and then I decided to implement a for loop for handling the adding of more than one feed to the list, and I tried the following (only the code for the second method in question):
#POST
#Consumes(MediaType.APPLICATION_XML)
#Produces(MediaType.APPLICATION_XML)
public String addXmlFeed() throws IOException
{
int i = 0;
String stringXml = "<feed><name>SMH Top Headlines</name><uri>http://feeds.smh.com.au/rssheadlines/top.xml</uri></feed><feed><name>UTS Library News</name>";
getFeedsFromXml(stringXml);
for (Feed feed: feeds)
{
Feed f = (Feed) feeds.get(i++);
feedList.add(f);
String handler = "You have successfully added: \n";
String xmlStringReply = "" + f + "\n";
}
feedList.save(feedFile);
return handler + xmlStringReply;
}
Now I'm sure this is a basic problem, but now in the line:
return handler + xmlStringReply;
handler and xmlStringReply cannot be resolved to a variable as they are within the FOR LOOP.
Is there any easy way around this?

The scope of those 2 variables is limited to the for loop. To access them outside the loop, you need to increase their scope by declaring them before the loop:
String handler = "";
String xmlStringReply = "";
for (Feed f: feeds) {
feedList.add(f);
handler = "You have successfully added: \n";
xmlStringReply = "" + f + "\n";
}
feedList.save(feedFile);
return handler + xmlStringReply;
Also, your current code overwrites the value of your strings at each loop, whereas you probably meant to concatenate the values. In that case, you could use a StringBuilder instead of string concatenation:
StringBuilder xmlStringReply = new StringBuilder("You have successfully added: \n");
for (Feed f: feeds) {
feedList.add(f);
xmlStringReply.append(f + "\n");
}
feedList.save(feedFile);
return xmlStringReply.toString();

The question you need to answer is "what do I want to return if I add several feeds ?".
Maybe you'd like to return "You have successfully added : feed1 feed2 feed3\n"
In that case, the code is :
StringBuilder response = new StringBuilder( "You have successfully added: ");
for (Feed feed: feeds)
{
feedList.add(feed);
response.append(f.toString()).append(" ");
}
feedList.save(feedFile);
return response.toString();
By the way, your feedand fvariables are just the same and redondant !
Don't write :
int i = 0;
for (Feed feed: feeds)
{
Feed f = (Feed) feeds.get(i++);
feedList.add(f);
}
but
for (Feed feed: feeds)
{
feedList.add(feed);
}

You need to accumulate the result into a variable. I am using StringBuilder because it makes string concatenation efficient.
#POST
#Consumes(MediaType.APPLICATION_XML)
#Produces(MediaType.APPLICATION_XML)
public String addXmlFeed() throws IOException
{
String stringXml = "<feed><name>SMH Top Headlines</name><uri>http://feeds.smh.com.au/rssheadlines/top.xml</uri></feed><feed><name>UTS Library News</name>";
getFeedsFromXml(stringXml);
StringBuilder replyBuilder = new StringBuilder("You have successfully added: \n");
for (Feed feed : feeds)
{
feedList.add(feed);
String xmlStringReply = feed + "\n";
reployBuilder.append(xmlStringReply);
}
feedList.save(feedFile);
return replyBuilder.toString();
}

Because, now they became out of scope.
Beside the original error -- you can easily fix that using other suggestions, I would like to suggest that you should not make feeds as instance variable. I can see your method getFeedsFromXml() is returning the list. So, I think it would have been better if you define that variable inside that method. And then, call the method like,
List<Feed> feeds = getFeedsFromXml(stringXml);
Or in case, this doesn't give you the desired behaviour, then you should rename the method to something, loadFeedsFromXml(). Making that as instance variable may result in threading issues.
Now, trying to improve on your looping,
StringBuilder xmlStringReply = new StringBuilder("You have successfully added: \n");
for (Feed feed: feeds) {
feedList.add(feed);
xmlStringReply.append(f + "\n");
}
feedList.save(feedFile);
return xmlStringReply.toString();
Moreover, I found that your feedList is also a instance variable. And this again can cause threading issues, as it doesn't sound immutable or stateless. Synchronising the methods will give you performance issues. See if you can make it local to this method. A rule of thumb is to keep variable scope as narrow as possible.

A good rule of thumb is to view scope like this:
{ //This is a constructor
int i;
} // This is a deconstructor
anything that is created / instantiated between the curlies only lives inside the curlies. Whenever your working with variables and loops:
for(int i = 0; i < 10; i++){
//some code here
} // after this curly i is no longer in scope or accessible.

Use JDT to get full method name

I am new to eclipse plugin development and I am trying to convert a IMethod to a string representation of the full method name. I.E.
my.full.package.ClassName.methodName(int param, String string)
so far I have had to hand roll my own solution. Is there a better way?
private static String getMethodFullName(IMethod iMethod)
{
String packageString = "[Default Package]";
try {
IPackageDeclaration[] declarations = iMethod.getCompilationUnit().getPackageDeclarations();
if(declarations.length > 0)
{
packageString = declarations[0].getElementName();
}
} catch (JavaModelException e) {
}
String classString = iMethod.getCompilationUnit().getElementName();
classString = classString.replaceAll(".java", "");
String methodString = iMethod.getElementName() + "(";
for (String type : iMethod.getParameterTypes()) {
methodString += type + ",";
}
methodString += ")";
return packageString + "." + classString + "." + methodString;
}

You can get the Fully qualified name for the type using
method.getDeclaringType().getFullyQualifiedName();
This is probably easier than accessing the package from the compilation unit. The rest of you function looks correct.
One small point: you should use StringBuilder to build up the string instead of adding to a standard String. Strings are immutable so addition creates loads of unrecesary temparary objects.
private static String getMethodFullName(IMethod iMethod)
{
StringBuilder name = new StringBuilder();
name.append(iMethod.getDeclaringType().getFullyQualifiedName());
name.append(".");
name.append(iMethod.getElementName());
name.append("(");
String comma = "";
for (String type : iMethod.getParameterTypes()) {
name.append(comma);
comma = ", ";
name.append(type);
}
name.append(")");
return name.toString();
}

Thanks to iain and some more research I have come up with this solution. It seems like something like this should be built into the JDT....
import org.eclipse.jdt.core.Signature;
private static String getMethodFullName(IMethod iMethod)
{
StringBuilder name = new StringBuilder();
name.append(iMethod.getDeclaringType().getFullyQualifiedName());
name.append(".");
name.append(iMethod.getElementName());
name.append("(");
String comma = "";
String[] parameterTypes = iMethod.getParameterTypes();
try {
String[] parameterNames = iMethod.getParameterNames();
for (int i=0; i<iMethod.getParameterTypes().length; ++i) {
name.append(comma);
name.append(Signature.toString(parameterTypes[i]));
name.append(" ");
name.append(parameterNames[i]);
comma = ", ";
}
} catch (JavaModelException e) {
}
name.append(")");
return name.toString();
}

I am not sure it would take into account all cases (method within an internal class, an anonymous class, with generic parameters...)
When it comes to methods signatures, the classes to look into are:
org.eclipse.jdt.internal.corext.codemanipulation.AddUnimplementedMethodsOperation
org.eclipse.jdt.internal.corext.codemanipulation.StubUtility2
You need to get the jdt.core.dom.IMethodBinding, from which you can extract all what you need.
If you have a MethodInvocation, you can:
//MethodInvocation node
ITypeBinding type = node.getExpression().resolveTypeBinding();
IMethodBinding method=node.resolveMethodBinding();