I'm using a spring framework and the code I'm using won't work or check if the query is null, though I used a .isEmpty() method it doesn't mean that the query is empty. I wanted to make sure that my query is empty because a part of my code does invoke an id in which case I didn't even though its null so please help me T.T
public List<Object> searchEmployee(EmployeeSearchDto data) {
Session session = sessionFactory.openSession();
final String CRITERIA_EMPLOYEEID = "emp.employeeID =:id";
final String CRITERIA_EMPLOYEEID2 = "emp.employeeID LIKE:id";
final String CRITERIA_POSITION= "emp.positionID =:posID";
final String CRITERIA_DEPARTMENT="emp.departmentID =:deptID";
final String CRITERIA_WORKPLACE = "emp.workplaceID =:workID";
Boolean selected_dept = false;
Boolean selected_pos = false;
Boolean selected_work = false;
Boolean input_empID = false;
Boolean input_empName = false;
firstName = "";
middleName = "";
lastName = "";
completeName = "";
firstLastName = "";
List<String> criteria = new ArrayList<>();
List<Object> employees = null;
// checking the fields if all the fields is empty
try{
//one by one check the select field
String query = "Select"
+ " emp.employeeID,"
+"emp.firstName,"
+"emp.middleName,"
+"emp.lastName,"
+"pos.positionName,"
+"dept.deptName,"
+"work.workplaceName"
+"from Employee emp "
+ "INNER JOIN Department dept "
+ "ON emp.departmentID = dept.deptID "
+ "INNER JOIN Position pos "
+ "ON emp.positionID = pos.positionID "
+ "INNER JOIN Workplace work "
+ "ON emp.workplaceID = work.workplaceID ";
if(!data.isEmpty()) {
query = query.concat("WHERE ");
if(data.getEmployeeID()!="" && data.getEmployeeID()!=null) {
criteria.add(CRITERIA_EMPLOYEEID2);
System.out.println("Employee IDs");
input_empID = true;
}
if(data.getEmployeeName()!="" && data.getEmployeeName()!=null){
criteria.add(nameCriteriaHelper(data.getEmployeeName()));
System.out.println("Employee Name AKOOO");
input_empName = true;
}
if(data.getDepartmentID()!=0) {
criteria.add(CRITERIA_DEPARTMENT);
System.out.println("Dept ID ");
selected_dept = true;
}
if(data.getPositionID()!=0) {
criteria.add(CRITERIA_POSITION);
System.out.println("POS ID ");
selected_pos = true;
}
if(data.getWorkplaceID()!=0) {
criteria.add(CRITERIA_WORKPLACE);
selected_work = true;
}
query = query.concat(String.join(" OR ", criteria));
}
query = query.concat(" ORDER BY emp.joinDate DESC");
System.out.println("QUERY: " + query);
Query q = session.createQuery(query);
if(input_empID) {
q.setParameter("id", "%" + data.getEmployeeID() + "%");
}
if(input_empName) {
if(searchbyOne)
q.setParameter("inputName", "%" + data.getEmployeeName() + "%");
if(searchbyFandL)
q.setParameter("firstLastName", "%" +firstLastName+ "%");
if(searchbyCompName)
q.setParameter("completeName", "%" +completeName+ "%");
}
if(selected_dept) {
q.setParameter("deptID", data.getDepartmentID());
}
if(selected_pos) {
q.setParameter("posID", data.getPositionID());
}
if(selected_work) {
q.setParameter("workID", data.getWorkplaceID());
}
employees = (List<Object>) q.list();
}catch(Exception e){
e.printStackTrace();
}finally{
session.close();
}
return employees;
}
public String nameCriteriaHelper(String name) {
searchbyOne = false;
searchbyFandL = false;
searchbyCompName = false;
final String noOfTokens_1 = "CONCAT(emp.lastName,' ',emp.firstName, ' ',emp.middleName) LIKE :inputName";
final String noOfTokens_2 = "(CONCAT(emp.lastName, ' ', emp.firstName) LIKE :firstLastName "
+ "OR CONCAT(emp.firstName, ' ', emp.lastName) LIKE :firstLastName)";
final String noOfTokens_3 = "CONCAT(emp.lastName,' ',emp.firstName, ' ',emp.middleName) LIKE :completeName";
StringTokenizer stringTokenizer = new StringTokenizer(name);
int no_of_tokens = stringTokenizer.countTokens();
switch(no_of_tokens) {
case 1: searchbyOne = true;
return noOfTokens_1;
case 2: firstName = stringTokenizer.nextToken();
lastName = stringTokenizer.nextToken();
firstLastName = lastName + " " + firstName;
searchbyFandL = true;
return noOfTokens_2;
default: int counter = 0;
while( counter < (no_of_tokens - 2)) {
firstName = firstName.concat(stringTokenizer.nextToken() + " ");
counter++;
}
firstName = stringTokenizer.nextToken();
middleName = stringTokenizer.nextToken();
lastName = stringTokenizer.nextToken();
completeName = lastName + " " + firstName + " " + middleName;
searchbyCompName = true;
return noOfTokens_3;
}
You're using wrong order and wrong function to compare string:
Replace:
data.getEmployeeID()!="" && data.getEmployeeID()!=null
With
data.getEmployeeID() != null && !data.getEmployeeID().equals("")
Comparing string must use equals(). And check for null should be done first, before accessing the equals method
You should correct other conditions as above too.
Actually, the logic that Mr. Nguyễn provided here is faulty. An object or variable cannot both be null and initialized to a default value (such as foo == "") at the same time.
At the time of the logic check, if the String is in fact null, the second half of the logic statement will engage, checking to see if the String is equal to "", which will throw a null pointer exception. Instead of checking for both at the same time, check for one and then check for the other like so:
//since two logic checks are being performed,
//it is advantageous to put the data from the query
//into memory so you don't have to get the
//same result twice
String foo = data.getEmployeeID();
if (foo != null)
{
if (!(foo.equals("")))
{
//the result is neither null or empty
}
else
{
//the result is not null but it is empty
}
}
else
{
//the result is null
}
Related
I tried to make an exporting data to PDF but when I try to export it, the pdf can't show up like "no data found"
this code on bean
public JasperPrint exportTo() {
if(this.listReportMaster == null || this.listReportMaster.isEmpty()){
FacesMessage messageFailed = new FacesMessage(FacesMessage.SEVERITY_INFO,"Info","No data found");
RequestContext.getCurrentInstance().showMessageInDialog(messageFailed);
return null;
}
String path = FacesContext.getCurrentInstance().getExternalContext().getRealPath("/resources/report/PRPKReportPDF.jasper");
JRBeanCollectionDataSource beanCollectionDataSource = new JRBeanCollectionDataSource(this.listReportMaster);
try {
JasperPrint jasperPrint = JasperFillManager.fillReport(path, null, beanCollectionDataSource);
return jasperPrint;
} catch (JRException e) {
e.printStackTrace();
return null;
}
}
public void exportToPdf(ActionEvent actionEvent){
if(this.lazyMasterReportDataModel != null){
System.out.println("masuk exporttopdf");
String sql = ((LazyMasterReportDataModel) this.lazyMasterReportDataModel).getSqlReportPrint();
List<Object> listObject = ((LazyMasterReportDataModel) this.lazyMasterReportDataModel).getObjectSqlListReportPrint();
this.listReportMaster = reportMasterPRPKController.getPRPKForReport(sql, listObject);
JasperPrint jasperPrint = exportTo();
String fileName = "PRPKNew_Report".concat("_").concat(".pdf");
if(jasperPrint != null) reportMasterPRPKController.exportToPDF(fileName, jasperPrint);
else System.out.println("jasperprint null");
}else{
System.out.println("keluar exporttopdf");
FacesMessage messageFailed = new FacesMessage(FacesMessage.SEVERITY_INFO,"Info","No data found");
RequestContext.getCurrentInstance().showMessageInDialog(messageFailed);
}
}
every I try to export it, always show "no data found" which is the program run this code FacesMessage messageFailed = new FacesMessage(FacesMessage.SEVERITY_INFO,"Info","No data found"); and which meam the "this.lazyMasterReportDataModel" is null but when I check it again, there's nothing wrong on code, I don't know if it have a wrong code or deficiency code
this the lazy code
List<ReportMasterPRPK> listMasterPRPK = new ArrayList<>();
ReportMasterPRPKQuery reportMasterPRPKQuery = new ReportMasterPRPKQuery();
Page page = new Page();
String order = "GROUP a.prpk_number, a.prpk_type_id, a.created_date, a.pic_prpk_id, a.business_unit_id, a.pic_department_id, a.prpk_desc, a.prpk_request, a.prpk_background, a.prpk_analysis_benefit, a.priority_level_id, a.cost, b.prpk_type_name, c.business_unit, d.department_name, e.priority_name, f.user_name ORDER BY a.created_date ";
String columname = "";
String sql = "";
List<Object> objectSqlList = new ArrayList<>();
String sqlReport = "";
String sqlReportPrint = "";
List<Object> objectSqlListReport = new ArrayList<>();
List<Object> objectSqlListReportPrint = new ArrayList<>();
String flag;
public LazyMasterReportDataModel() {
}
public LazyMasterReportDataModel(String flag) { //ini
this.flag = flag;
}
public LazyMasterReportDataModel(String sqlReport, List<Object> objectSqlListReport) {
this.sqlReport = sqlReport;
this.objectSqlListReport = objectSqlListReport;
}
#Override
public List<ReportMasterPRPK> load(int first, int pageSize, String sortField, SortOrder sortOrder,
Map<String, Object> filters) {
page.setLimit(pageSize);
page.setOffset(first);
if(this.sqlReport != null){
this.sql = this.sqlReport;
this.objectSqlList = this.objectSqlListReport;
}else{
sql = "";
objectSqlList = new ArrayList<>();
//objectSqlList.clear();
}
if(flag != null){ //ini
if(flag.equals("no selected")){
sql = sql+" AND c.is_selected = 'n' ";
}
}
if (filters != null){
for(String key: filters.keySet()){
String filterColumnName = "";
for(Field field : ReportMasterPRPK.class.getDeclaredFields()){
if(field.getName().equals(key)) filterColumnName = field.getAnnotation(Column.class).value();
}
if(filters.get(key) instanceof String){
if("receivedDate".equals(key)){
if(((String)filters.get(key)).trim().length() > 20){
String startDate = "'" + filters.get(key).toString().substring(0, 10) + "'";
String endDate = "'" + filters.get(key).toString().substring(11, 21) + "'";
sql = sql + " AND " + filterColumnName + " BETWEEN " + startDate + " AND " + endDate+ " ";
}
}else{
if(((String) filters.get(key)).trim().length() > 0){
sql = sql+"AND "+filterColumnName+" ILIKE ? ";
String value = "%"+filters.get(key)+"%";
objectSqlList.add(value);
}
}
}else{
if(((String[]) filters.get(key)).length > 0){
sql = sql+" AND "+filterColumnName+" in ";
String value = "(";
for(String string : (String[]) filters.get(key)){
value = value+"'"+string+"',";
}
value = value.substring(0, value.length()-1)+") ";
sql = sql + value;
}
}
}
}
if(sortField != null){
for(Field field : ReportMasterPRPK.class.getDeclaredFields()){
if(field.getName().equals(sortField)) columname = field.getAnnotation(Column.class).value();
}
if(sortOrder.toString().equals("ASCENDING")) order = " ASC";
else order = " DESC";
sql = sql+" GROUP a.prpk_number, a.prpk_type_id, a.created_date, a.pic_prpk_id, a.business_unit_id, a.pic_department_id, a.prpk_desc, a.prpk_request, a.prpk_background, a.prpk_analysis_benefit, a.priority_level_id, a.cost, b.prpk_type_name, c.business_unit, d.department_name, e.priority_name, f.user_name ORDER BY "+columname+" "+order;
System.out.println("sql sort: "+sql+" : "+objectSqlList.size());
}else{
sql = sql + order;
}
sqlReportPrint = sql;
objectSqlListReportPrint = objectSqlList;
this.listMasterPRPK = reportMasterPRPKQuery.retrivePage(page, sql, objectSqlList.toArray());
int dataSize = reportMasterPRPKQuery.retrieveMaxRow(sql, objectSqlList.toArray());
this.setRowCount(dataSize);
//objectSqlList.clear();
if(this.sqlReport != null){
this.sql = this.sqlReport;
this.objectSqlList = this.objectSqlListReport;
}else{
sql = "";
objectSqlList.clear();
}
order = "GROUP a.prpk_number, a.prpk_type_id, a.created_date, a.pic_prpk_id, a.business_unit_id, a.pic_department_id, a.prpk_desc, a.prpk_request, a.prpk_background, a.prpk_analysis_benefit, a.priority_level_id, a.cost, b.prpk_type_name, c.business_unit, d.department_name, e.priority_name, f.user_name ORDER BY a.created_date ";
return listMasterPRPK;
}
public List<ReportMasterPRPK> calculateRownum(List<ReportMasterPRPK> listMasterPRPK, int first){
int i = 1;
for (ReportMasterPRPK masterPRPK : listMasterPRPK) {
masterPRPK.setRownum(first + i);
i++;
}
return listMasterPRPK;
}
public String getSqlReportPrint() {
return sqlReportPrint;
}
public void setSqlReportPrint(String sqlReportPrint) {
this.sqlReportPrint = sqlReportPrint;
}
public List<Object> getObjectSqlListReportPrint() {
return objectSqlListReportPrint;
}
public void setObjectSqlListReportPrint(List<Object> objectSqlListReportPrint) {
this.objectSqlListReportPrint = objectSqlListReportPrint;
}
sorry before, if my english is to bad, but I hope you understand about what I mean...
thanks before...
Why doesn't this query work?
query = "SELECT itm.itemId, itm.itemModel, itm.itemDescription, "
+ " itmImages.imageFileName, part.participant_id "
+ " FROM Users user "
+ " INNER JOIN user.participant part "
+ " INNER JOIN part.addresses addr "
+ " INNER JOIN part.item itm "
+ " INNER JOIN itm.itemImages itmImages "
+ " WHERE user.userType LIKE '%borrow%') AND itm.itemDescription LIKE '%mower%') AND addr.addressType = 'primary'";
It always returns all items, disregards itemDescription LIKE... I checked the database and all of the join ids are fine
This works:
query = "SELECT user"
+ " FROM Users user "
+ " INNER JOIN user.participant part "
+ " INNER JOIN part.addresses addr "
+ " WHERE user.userType LIKE '%borrow%') AND addr.addressType = 'primary'";
I have a table Users. It has a one-to-many association with table Participant.
In Users.java I have..
private Set<Participant> participant = new HashSet<Participant>();
with
#OneToMany
#JoinTable(name = "echomarket.hibernate.Participant")
#JoinColumn(name = "user_id")
public Set<Participant> getParticipant() {
return participant;
}
public void setParticipant(Set<Participant> participant) {
this.participant = participant;
}
This join works fine.
In Participant.java I have
private Set<Addresses> addresses = new HashSet<Addresses>();
with
#OneToMany
#JoinTable(name = "echomarket.hibernate.Addresses")
#JoinColumn(name = "participant_id")
public Set<Addresses> getAddresses() {
return addresses;
}
public void setAddresses(Set<Addresses> addresses) {
this.addresses = addresses;
}
And
private Set item = new HashSet();
With
#OneToMany
#JoinTable(name = "echomarket.hibernate.Items")
#JoinColumn(name = "participant_id")
public Set<Items> getItem() {
return item;
}
No association statement with regard to Users.
In Addresses.java I make no associations.
In Items.java I have
private Set<ItemImages> itemImages = new HashSet<ItemImages>();
with
#OneToMany
#JoinTable(name = "echomarket.hibernate.ItemImages")
#JoinColumn(name = "itemId")
public Set<ItemImages> getItemImages() {
return itemImages;
}
public void setItemImages(Set<ItemImages> itemImages) {
this.itemImages = itemImages;
}
In ItemImages.java I make no associations...
Very much thanks for your help. If you need more information, please just ask...
Liz
Couldn't get the above INNER JOIN query to work-- intended for a search that involves many tables. I tested each JOIN independently successfully, but together the JOIN does not work. Also had problems with query recognizing LIKE statement. I worked really hard to find solutions. So I rewrote with the following, data gathering is split in two query calls. The following works:
public String SearchResults() {
Session sb = null;
Transaction tx = null;
String queryString = "";
String forceString = this.found_zip_codes;
List results = null;
String fromStatement = "";
if (this.lenderOrBorrower == 2) {
this.which = "borrow";
} else {
this.which = "lend";
}
this.imageLibrary = this.which + "_images";
fromStatement = " SELECT part "
+ " FROM Participant part "
+ " INNER JOIN part.addresses addr "
+ " WHERE addr.addressType = 'primary' ";
if (ubean.getComDetailID() != null) {
fromStatement = fromStatement + " AND part.communityId = \'" + ubean.getComDetailID() + "\' ";
} else {
fromStatement = fromStatement + " AND part.communityId = ''";
}
if (this.postalCode.isEmpty() == false) {
fromStatement = fromStatement + " OR addr.postalCode LIKE \'" + this.postalCode + "%\'";
}
try {
sb = hib_session();
tx = sb.beginTransaction();
results = sb.createQuery(fromStatement).list();
tx.commit();
} catch (Exception ex) {
tx.rollback();
Logger.getLogger(SearchesBean.class.getName()).log(Level.SEVERE, null, ex);
} finally {
tx = null;
sb = null;
}
String[] pids = new String[results.size()];
String hold_pid = "";
if (results != null) {
if (results.size() > 0) {
for (int i = 0; i < results.size(); i++) {
Participant cArray = (Participant) results.get(i);
if (cArray.getParticipant_id().isEmpty() == false) {
hold_pid = "\'" + cArray.getParticipant_id() + "\'";
pids[i] = hold_pid;
}
}
hold_pid = String.join(",", pids);
}
}
results = null;
fromStatement = " FROM Items itm WHERE itm.itemType = :which "
+ (hold_pid.isEmpty() ? "" : " AND itm.participant_id IN ( " + hold_pid + " )");
if ((this.startDate.isEmpty() == false) && (this.endDate.isEmpty() == false)) {
try {
queryString = queryString + " OR ";
queryString = queryString + " ( itm.dateCreated >= \'" + this.startDate + "\' AND itm.dateCreated <= \'" + this.endDate + "\' ) ";
} catch (Exception ex) {
Logger.getLogger(SearchesBean.class.getName()).log(Level.INFO, null, ex);
}
}
forceString = this.keyword;
if (forceString.isEmpty() == false) {
queryString = queryString + " OR ";
queryString = queryString + " (itm.itemDescription like \'%" + forceString + "%\' OR itm.itemModel like \'%" + forceString + "%\')";
}
if ((this.categoryId != -2)) {
queryString = queryString + " OR";
queryString = queryString + " itm.categoryId = " + this.categoryId;
}
fromStatement = fromStatement + queryString;
try {
sb = hib_session();
tx = sb.beginTransaction();
results = sb.createQuery(fromStatement).setParameter("which", this.which).list();
tx.commit();
} catch (Exception ex) {
tx.rollback();
Logger.getLogger(SearchesBean.class.getName()).log(Level.SEVERE, null, ex);
} finally {
tx = null;
sb = null;
}
this.itemDetail = results;
return "search";
}
I'm working a project(Full source code here) and as part of the project, I've created a Database class to make interfacing with the SQLite database easier and cleaner. I'm currently attempting to write a method that will use SELECT along with the given parameters to return a string array containing the results. The issue that I'm having is that when I run the program to test it, Eclipse throws java.sql.SQLException: no such column: 'MOVES'
But, when I look at the database in a GUI, it clearly shows the column that I'm trying to access, and when I execute just the sql in the same program, it's able to return the data.
This is the method that I've written so far:
public String[] get(String what, String table, String[] conds) {
try {
if (what.equals("*")) {
throw new Exception("'*' selector not supported");
}
c.setAutoCommit(false);
stmt = c.createStatement();
String sql = "SELECT " + what.toUpperCase() + " FROM " + table.toUpperCase();
if (conds.length > 0) {
sql += " where ";
for (int i = 0; i < conds.length; i++) {
if (i == conds.length - 1) {
sql += conds[i];
break;
}
sql += conds[i] + " AND ";
}
}
sql += ";";
System.out.println(sql);
ResultSet rs = stmt.executeQuery(sql);
while (rs.next()) {
if (table.toUpperCase().equals("DEX")) {
String id = "";//rs.getInt("id") + "";
String species = rs.getString("species");
String type1 = rs.getString("type1");
String type2 = rs.getString("type2");
String hp = rs.getInt("hp") + "";
String atk = rs.getInt("atk") + "";
String def = rs.getInt("def") + "";
String spa = rs.getInt("spa") + "";
String spd = rs.getInt("spd") + "";
String spe = rs.getInt("spe") + "";
String ab1 = rs.getString("ab1");
String ab2 = rs.getString("ab2");
String hab = rs.getString("hab");
String weight = rs.getString("weight");
return new String[] { id, species, type1, type2, hp, atk, def, spa, spd, spe, ab1, ab2, hab,
weight };
} else if (table.toUpperCase().equals("MOVES")) {
String name = rs.getString("NAME");
String flags = rs.getString("FLAGS");
String type = rs.getString("TYPE");
String full = rs.getString("LONG");
String abbr = rs.getString("SHORT");
String acc = rs.getInt("ACCURACY") + "";
String base = rs.getInt("BASE") + "";
String category = rs.getInt("CATEGORY") + "";
String pp = rs.getInt("PP") + "";
String priority = rs.getInt("PRIORITY") + "";
String viable = rs.getInt("VIABLE") + "";
return new String[] { name, acc, base, category, pp, priority, flags, type, full, abbr, viable };
} else if (table.toUpperCase().equals("LEARNSETS")) {
String species = rs.getString("SPECIES");
String moves = rs.getString("MOVES");
return new String[] { species, moves };
} else {
throw new Exception("Table not found");
}
}
rs.close();
stmt.close();
c.close();
} catch (Exception e) {
System.err.println(e.getClass().getName() + ": " + e.getMessage());
System.exit(0);
}
return null;
}
Screencaps:
UPDATE:
I wanted to double-check that the database viewer I was using wasn't messed up, so I opened up the terminal and ran
sqlite3 git/Pokemon/data.db
pragma table_info(MOVES);
Receiving this in response:
0|SPECIES|TEXT|0||0
1|MOVES|TEXT|0||0
Finally figured it out, for anybody else having this issue, make sure that the data you're trying to get from the result set is actually included in it. For example, if I call SELECT SPECIES FROM DEX; the result set won't contain other things like id, type, or any of those other columns, it will ONLY contain the species column. I'm not sure why it took me so long to figure this out, but there you have it.
I'm generating an SQL statement by checking if each of the column fields submitted to the query are empty (== null) or not. It seems that my approach is pretty naive so I'm wondering what can be done about handling null parameters elegantly. When something isn't specified it should simply match anything.
Here is the code:
public List<Flight> findMatchingFlights(Flight flight)
{
List<Flight> foundFlights = new ArrayList<>();
StringBuilder sqlQueryBuilder = new StringBuilder();
sqlQueryBuilder.append("SELECT * FROM Flights");
boolean emptyQuery = true;
if(flight.getDeparture() != null)
{
if(emptyQuery)
{
sqlQueryBuilder.append(" WHERE ");
emptyQuery = false;
}
sqlQueryBuilder.append("Departure = '" + flight.getDeparture() + "'");
}
if(flight.getArrival() != null)
{
if(emptyQuery)
{
sqlQueryBuilder.append(" WHERE ");
emptyQuery = false;
}
else
{
sqlQueryBuilder.append(" AND ");
}
sqlQueryBuilder.append("Arrival = '" + flight.getArrival() + "'");
}
if(flight.getFlightNumber() != null)
{
if(emptyQuery)
{
sqlQueryBuilder.append(" WHERE ");
emptyQuery = false;
}
else
{
sqlQueryBuilder.append(" AND ");
}
sqlQueryBuilder.append("Number = '" + flight.getFlightNumber() + "'");
}
if(flight.getFlightMinutes() != 0)
{
if(emptyQuery)
{
sqlQueryBuilder.append(" WHERE ");
emptyQuery = false;
}
else
{
sqlQueryBuilder.append(" AND ");
}
sqlQueryBuilder.append("Duration = " + flight.getFlightMinutes());
}
/*
...
A bunch more fields
*/
if(flight.getAirplane() != null)
{
if(emptyQuery)
{
sqlQueryBuilder.append(" WHERE ");
}
else
{
sqlQueryBuilder.append(" AND ");
}
sqlQueryBuilder.append("Airplane = '" + flight.getAirplane() + "'");
}
sqlQueryBuilder.append(";");
// Execute sql and fill list with rows that match
}
You can create the common method for the below block and call the method by passing the arguments.
if(flight.getArrival() != null)
{
if(emptyQuery)
{
sqlQueryBuilder.append(" WHERE ");
emptyQuery = false;
}
else
{
sqlQueryBuilder.append(" AND ");
}
sqlQueryBuilder.append("Arrival = '" + flight.getArrival() + "'");
}
Best approach would be to do the trick in SQL than checking for null in Java. This is how you can do it.
sqlQueryBuilder.append("(Number = '" + flight.getFlightNumber() + "' OR " + flight.getFlightNumber() + " IS NULL)");
This way you wont have to check null in java, if the flight.getFlightNumber() is null then this where clause will always return true which is what you would want.
The only drawback to this method is that the clause will be included in the query, but since you are intending to use these columns to query the table incase they are not null, i would assume the table would be indexed likewise.
sqlQueryBuilder.append("SELECT * FROM Flights WHERE 1 = 1");
then you don't need emptyQuery flag and checks and many if else constractions.
List<Flight> foundFlights = new ArrayList<>();
StringBuilder sqlQueryBuilder = new StringBuilder();
sqlQueryBuilder.append("SELECT * FROM Flights WHERE 1 = 1");
if(flight.getDeparture() != null) {
sqlQueryBuilder.append("AND Departure = '" + flight.getDeparture() + "'");
}
Hi I'm trying to filter records on the basis of Brand,Flavor,Price,Size,Type. i am using a single form to handle this so if user filter only by brand then rest of options like price,flavor will be unchecked so i am checking if Brand or flavor or price is null.I got the solution but i have make lot of comparisons for all cases. i need a solution by which i have make less comparisons.I am using following code
public List<Products> Filter_Items(String[] Brand, String[] Flavour,Float Price,String Size,String Type)
{
ResultSet rs;
List<Products> data = null;
PreparedStatement stmt;
try {
StringBuilder param = new StringBuilder();
if (Brand != null) {
for (String str : Brand) {
param.append("'").append(str).append("', ");
}
}
StringBuilder param1 = new StringBuilder();
if (Flavour != null) {
for (String str : Flavour) {
param1.append("'").append(str).append("', ");
}
}
String prm = param.toString().length() > 2 ? param.toString()
.substring(0, param.toString().length() - 2) : null;
String prm1 = param1.toString().length() > 2 ? param1.toString()
.substring(0, param1.toString().length() - 2) : null;
String query = "select * from products where ";
if (prm != null && prm1 != null) {
query += "Brand in (" + prm + ") and Flavour in (" + prm1 + ")";
} else if (prm != null && prm1 == null) {
query += "Brand in (" + prm + ")";
} else if (prm1 != null && prm == null) {
query += "Flavour in (" + prm1 + ")";
}
stmt = DataBaseConnection.DBConn.getConnection().prepareStatement(query);
rs = stmt.executeQuery();
if (rs != null) {
data = new ArrayList<Products>();
while (rs.next()) {
Products p = new Products();
p.setTitle(rs.getString("Ttile"));
p.setCategory(rs.getString("Category"));
p.setSubCategory(rs.getString("SubCategory"));
p.setSubCategoryTwo(rs.getString("SubCategorytwo"));
p.setPrice(rs.getInt("Price"));
p.setFlavour(rs.getString("Flavour"));
p.setSize(rs.getString("Size"));
p.setImage(rs.getString("image"));
p.setBrand(rs.getString("Brand"));
p.setInstock(rs.getString("instock"));
p.setInstockQty(rs.getInt("instockqty"));
data.add(p);
}
}
} catch (Exception e) {
System.out.println(e.getStackTrace());
return null;
}
return data;
}
}
You can use as always third party libraries for validation like javax validation or any other more specialized on this.
You could create a bean of your data with all the getters and setters and apply validation on your bean.
To pass arrays you need getters and setters like this one:
public class Foo {
private int[] array;
public Foo(int[] array) {
this.array = Arrays.copyOf(array, array.length);
}
/** #param the array to use */
public setArray(int[] array) {
this.array = Arrays.copyOf(array, array.length);
}
/** #return a copy of the array */
public int[] getArray() {
return Arrays.copyOf(array, array.length);
}
}
To validate a bean see this tutorial.
What you really need is to start naming variables according to what they are logically. Names like prm and prm1 are meaningless, while brand and flavor make more sense as variable names since that's what's in them.
I don't see the number of comparisons as a problem. But giving everything generic variable names and then not even indenting the if-statements makes my eyes glaze over.
How about something like this:
if (brand != null && flavor != null)
{
query += "Brand in (" + brand + ") and Flavour in (" + flavor + ")";
}
else if (brand != null && flavor == null)
{
query += "Brand in (" + brand + ")";
}
else if (flavor != null && brand == null)
{
query += "Flavour in (" + flavor + ")";
}
Edit: One thing you can do is split your SQL into two variables, one for the main query and one for the where clause, then just add to the where clause like this:
private String addToWhereClause(String currentWhereClause, String fieldname, String value)
{
String returnValue = "";
if (value != null)
{
if(!"".equals(currentWhereClause))
{
returnValue += " AND ";
}
returnValue += " "+fieldname+" IN(" + value + ") ";
}
return returnValue;
}
String whereClause = "";
whereClause += addToWhereClause(whereClause, "Brand", brand);
whereClause += addToWhereClause(whereClause, "Flavour", flavor);
query = query + " " + whereClause;