I want to insert the data in array so I can access specific values and display them. I am a newbie to java and I would like the answer to be simple.
try {
Statement stmt = conn.createStatement();
String sql = "SELECT * FROM " + tableName;
ResultSet results = stmt.executeQuery(sql);
ResultSetMetaData rsmt = results.getMetaData();
int numberOfColumns = rsmt.getColumnCount();
for (int i = 1; i <= numberOfColumns; i++) {
System.out.print(rsmt.getColumnLabel(i) + "\t\t\t");
}
System.out.println("\n-------------------------------------------------------------------------------");
while (results.next()) {
int s_no = results.getInt(1);
String s_name = results.getString(2);
String s_surname = results.getString(3);
System.out.println(s_no + "\t\t\t" + s_name + "\t\t\t" + s_surname);
}
results.close();
stmt.close();
} catch (Exception e) {
JOptionPane.showMessageDialog(null, "Records were not returned", "Error", JOptionPane.ERROR_MESSAGE);
System.out.println(e.getMessage());
}
storing resultset data in array is not possible.
better to create pojo class Student
public class Student {
private int s_no;
private String s_name;
private String s_surname;
public int getS_no() {
return s_no;
}
public void setS_no(int s_no) {
this.s_no = s_no;
}
public String getS_name() {
return s_name;
}
public void setS_name(String s_name) {
this.s_name = s_name;
}
public String getS_surname() {
return s_surname;
}
public void setS_surname(String s_surname) {
this.s_surname = s_surname;
}
}
Storing logic :-
ResultSet results = stmt.executeQuery(sql);
List<Student> studs = new ArrayList<Student>();
while (results.next()){
Student stud = new Student();
stud.setS_no(results.getInt(1));
stud.setS_name(results.getString(2));
stud.setS_surname(results.getString(3));
studs.add(stud);
}
all students have been added in list. Please iterate this list to fetch student data.
hope this will work for you
Related
I'm doing a phone book project in Java, using MySql for school.
I wanted to print the methods using the Class.getDeclaredMethods();
adding them to a Vector of type String.
and invoke a menu() method that prints and accepts the option from the user using Scanner
the problem is that it always changes the methods places.
for example it can print
0.addPerson
1.deleteContact
2.searchByChar
and the next time
0.deleteContact
1.addPerson
2.searchByChar.
the problem is that i have a Switch case depend on it.
the menu function:
public static int menu(Vector<?> options){
System.out.println("The Options: ");
for (int i = 0; i < options.size(); i++) {
System.out.println(i + ". " + options.get(i));
}
Scanner scanner = new Scanner(System.in);
System.out.println("Your Choice: ");
String optionString = scanner.nextLine();
int option = 0;
if(isNumber(optionString)){
option = Integer.valueOf(optionString);
}else{
System.out.println("Please Choose Valid Option");
return menu(options);
}
return option;
}
the methods that get my methods:
public static Vector<String> getClassMethods(Class whichClass){
Method[] methods = whichClass.getDeclaredMethods();
Vector<String> stringMethods = new Vector<>();
for (Method method : methods) {
if(Modifier.toString(method.getModifiers()).equals("protected")){
stringMethods.add(method.getName());
}
}
return stringMethods;
}
my class the connects to the data base:
private boolean getData(Person person){
String sql = "SELECT * FROM " + DB_NAME + " WHERE name = '" + person.getName() + "' and phone_number = '" + person.getPhoneNumber() + "'";
try {
ResultSet resultSet = db.prepareStatement(sql).executeQuery();
if (resultSet.next()) {
return true;
}
} catch (SQLException e) {
System.out.println(e.getMessage());
}
return false;
}
protected void addPerson(){
Person person = MyUtills.createPerson();
if(getData(person)){
System.out.println(person.getName() + ", " + person.getPhoneNumber() + ": Already in Contacts" );
}else{
add(person);
}
}
private void add(Person person) {
String pName = person.getName();
String pPhone = person.getPhoneNumber();
String pAddress = person.getAddress();
String sql = "INSERT INTO " + DB_NAME + " (name,phone_number,address)" +
"VALUES (?,?,?)";
try {
statement = db.prepareStatement(sql);
statement.setString(1,pName);
statement.setString(2,pPhone);
statement.setString(3,pAddress);
statement.execute();
System.out.println("Added Successfully");
} catch (SQLException e) {
e.printStackTrace();
}
}
//delete contact by name
protected void deleteContact(){
System.out.println("Enter Name Please");
String name = MyUtills.readStringFromUser();
Vector<Person> vector = checkMoreThanOne(name);
if(vector.size() > 1){
System.out.println("Choose One To Delete: ");
int option = menu(vector);
delete(vector.get(option));
}
System.out.println("Deleted");
}
private Vector<Person> checkMoreThanOne(String name) {
Vector<Person> vector = new Vector<>();
String sql = "SELECT * FROM " + DB_NAME;
try {
ResultSet resultSet = db.prepareStatement(sql).executeQuery();
while(resultSet.next()){
String pName = resultSet.getString("name");
String pPhone = resultSet.getString("phone_number");
String pAddress = resultSet.getString("address");
if(pName.equals(name)){
vector.add(new Person(pName,pPhone,pAddress));
}
}
return vector;
} catch (SQLException e) {
e.printStackTrace();
}
return null;
}
//deleting and existing contact;
private void delete(Person person){
String sql = "DELETE FROM " + DB_NAME + " WHERE name = '" + person.getName() + "' and phone_number = '" + person.getPhoneNumber() + "'";
try {
statement = db.prepareStatement(sql);
statement.execute();
System.out.println("Deleted Successfully");
} catch (SQLException e) {
e.printStackTrace();
}
}
//creating a new table for empty data base!
private void createTable() {
try {
statement = db.prepareStatement(SQL_TABLE_STRING);
statement.execute();
} catch (SQLException e) {
e.printStackTrace();
}
}
protected void searchByFirstChar(Character character){
Vector<Person> personVector = new Vector<>();
String sql = "SELECT * FROM newphonebook";
try {
ResultSet resultSet = db.prepareStatement(sql).executeQuery();
while(resultSet.next()){
String name = resultSet.getString("name");
String phoneNum = resultSet.getString("phone_number");
String address = resultSet.getString("address");
if(character.equals(name.charAt(0))){
personVector.add(new Person(name,phoneNum,address));
}
}
System.out.println(personVector);
} catch (SQLException e) {
System.out.println(e.getMessage());
}
}
public void getOptions(){
Vector<String> options = MyUtills.getClassMethods(DBWriterReader.class);
int option = MyUtills.menu(options);
switch (option){
case 0:
addPerson();
break;
case 1:
deleteContact();
break;
case 2:
// searchByFirstChar();
break;
}
}
}
I know it's not best written but I'm working on it to make it better
The Writing and Reading from the data base works fine, its the way it prints my methods that makes the problem..
If you need to guarantee the order of elements in a data structure, you don't use Vector -- it's not 1999 anymore. Look at the documentation for Vector. You get elements in the order determined by an iterator, not as they are stored.
Change your data structure to an ArrayList, which guarantees order. ArrayLists are also more performant in a single threaded application like yours, because unlike Vector, an ArrayList skips the overhead associated with being synchronized. Using the index of the ArrayList elements may also simplify the way you construct your switch statement.
I use a jTable jquery for jsp page, it work very well. It can display the showing count records in bottom right of table well (e.g. Showing 1-10 of 22). When I insert the Filtering into the page, the showing count record is not correctly.
I follow this for Filtering: http://www.jtable.org/Demo/Filtering
How to customize the code for showing count record (I use java-jsp and sql server). Sorry for my English language :))
Here is the code I am using right now in controller.
if (action.equals("list")) {
try {
int startPageIndex = Integer.parseInt(request.getParameter("jtStartIndex"));
int numRecordsPerPage = Integer.parseInt(request.getParameter("jtPageSize"));
String jtSorting = null;
//Fetch Data from Rejected_Product Table
lstSite = dao.**getAllSite**(filter_site, startPageIndex, numRecordsPerPage, jtSorting);
//Get Total Record Count for Pagination
int siteCount = dao.**getSiteCount**();
//Convert Java Object to Json
Gson gson = new Gson();
JsonElement element = gson.toJsonTree(lstSite, new TypeToken<List<Site>>() {
}.getType());
JsonArray jsonArray = element.getAsJsonArray();
String listData = jsonArray.toString();
//Return Json in the format required by jTable plugin
listData = "{\"Result\":\"OK\",\"Records\":"+listData+",\"TotalRecordCount\":"+siteCount+"}";
response.getWriter().print(listData);
System.out.println(listData);
} catch (Exception ex) {
String error = "{\"Result\":\"ERROR\",\"Message\":" + ex.getStackTrace() + "}";
response.getWriter().print(error);
ex.printStackTrace();
}
}
and here method getAllSite:
public List<Site> getAllSite (FilterSite filter_site, int jtStartIndex, int jtPageSize, String jtSorting) {
List<Site> siteList = new ArrayList<Site>();
String query = "";
String siteQ = filter_site.getSite();
String clientQ = filter_site.getClient(); // wait
String locationQ = filter_site.getLocation();
if (locationQ.isEmpty()) {
locationQ = "";
} else {
locationQ = "and location like '%"+locationQ+"' ";
}
String site_idQ = filter_site.getSite_id();
if (site_idQ.isEmpty()) {
site_idQ = "";
} else {
site_idQ = "and site_id = '"+site_idQ+"' ";
}
String divisionQ = filter_site.getDivision();
if (divisionQ.isEmpty()) {
divisionQ = "";
} else {
divisionQ = "and division = '"+divisionQ+"' ";
}
int range = jtStartIndex+jtPageSize;
query = "SELECT * FROM (SELECT *, ROW_NUMBER() OVER (ORDER BY CODE) as row FROM [site]) a "
+ "WHERE (code like '%"+siteQ+"' "+locationQ+site_idQ+divisionQ+") "
+ "and row > "+jtStartIndex+" and row <= "+range;
try {
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery(query);
System.out.println("query : "+query);
while (rs.next()) {
Site sitebean = new Site();
sitebean.setName(rs.getString("name"));
sitebean.setCode(rs.getString("code"));
.....
siteList.add(sitebean);
}
} catch (SQLException e) {
e.printStackTrace();
}
return siteList;
}
and here method getSiteCount :
public int getSiteCount () {
int count = 0;
String query = "SELECT COUNT(*) as count FROM [site] ";
try {
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery(query);
while (rs.next()) {
count = rs.getInt("count");
}
} catch (SQLException e) {
e.printStackTrace();
}
return count;
}
If you mean by "not correctly" that the row count is larger than expected, then the solution would be to include the where clause in the siteCount query.
WHERE (code like '%"+siteQ+"' "+locationQ+site_idQ+divisionQ+")
I have a JFrame that has 3 JTextfields and 2 JDatechooser, what I am trying to do is if only one JTextfield has something typed in it and I press the search button, then I will be able to retrieve the data to JTable, but the problem is I have to fill out all JTextFileds and JDatechooser in order to retrieve data. My idea is to ignore null JTextfields and JTdatechooser if only one JTextfield has the keyword I want ?? Any suggestions ?? Thanks in advance,
public ArrayList<BillsRecord> getBillRecordByID(int EmpCode, String Fname, String Lname, String sDate, String eDate) throws SQLException {
String sql = "SELECT B.DATE AS DT, B.EMP_ID, E.FNAME, E.LNAME, MONEY_SENT, RENT, PHONE, GAS, ELECTRICITY, INTERNET, OTHER"
+ " FROM EMPLOYEE E INNER JOIN BILLS B ON E.EMP_ID = B.EMP_ID"
+ " WHERE B.EMP_ID = ? "
+ " OR E.FNAME = ? "
+ " OR E.LNAME = ? "
+ " OR DATE BETWEEN ? AND ? "
+ " ORDER BY B.DATE";
DBConnection con = new DBConnection();
Connection connect = con.getConnection();
PreparedStatement ps = null;
ArrayList<BillsRecord> records = new ArrayList<>();
try {
ps = connect.prepareStatement(sql);
ps.setInt(1, EmpCode);
ps.setString(2, Fname);
ps.setString(3, Lname);
ps.setString(4, sDate);
ps.setString(5, eDate);
ResultSet rs = ps.executeQuery();
if (rs.next()) {
BillsRecord billrec = new BillsRecord();
billrec.setDATE(rs.getString("DT"));
billrec.setEMP_ID(rs.getInt("EMP_ID"));
billrec.setFNAME(rs.getString("FNAME"));
billrec.setLNAME(rs.getString("LNAME"));
billrec.setMONEY_SENT(rs.getDouble("MONEY_SENT"));
billrec.setRENT(rs.getDouble("RENT"));
billrec.setPHONE(rs.getDouble("PHONE"));
billrec.setGAS(rs.getDouble("GAS"));
billrec.setELECTRICITY(rs.getDouble("ELECTRICITY"));
billrec.setINTERNET(rs.getDouble("INTERNET"));
billrec.setOTHER(rs.getDouble("OTHER"));
records.add(billrec);
return records;
}
} catch (SQLException e) {
System.out.println(e.toString());
} finally {
if (ps != null) {
ps.close();
}
if (connect != null) {
connect.close();
}
}
return null;
}
private void search() {
try {
JTextField stxt = ((JTextField) startdatetxt.getDateEditor().getUiComponent());
String sDATE = stxt.getText().trim();
JTextField etxt = ((JTextField) enddatetxt.getDateEditor().getUiComponent());
String eDATE = etxt.getText().trim();
int EMP_ID = Integer.parseInt(this.empidtxt.getText().trim());
String FNAME = this.firstnametxt.getText().trim();
String LNAME = this.lastnametxt.getText().trim();
BillRecordDao billrecdao = new BillRecordDao();
ArrayList<BillsRecord> records = billrecdao.getBillRecordByID(EMP_ID, FNAME, LNAME, sDATE, eDATE);
Object[] tableColumnName = new Object[11];
tableColumnName[0] = "Date";
tableColumnName[1] = "H.License";
tableColumnName[2] = "First Name";
tableColumnName[3] = "Last Name";
tableColumnName[4] = "MONEY SENT";
tableColumnName[5] = "RENT";
tableColumnName[6] = "PHONE";
tableColumnName[7] = "GASE";
tableColumnName[8] = "ELECTRICITY";
tableColumnName[9] = "INTERNET";
tableColumnName[10] = "OTHER";
DefaultTableModel tbd = new DefaultTableModel();
tbd.setColumnIdentifiers(tableColumnName);
this.BillsSummaryTable.setModel(tbd);
Object[] RowRec = new Object[11];
for (int i = 0; i < records.size(); i++) {
RowRec[0] = records.get(i).getDATE();
RowRec[1] = records.get(i).getEMP_ID();
RowRec[2] = records.get(i).getFNAME().toUpperCase();
RowRec[3] = records.get(i).getLNAME().toUpperCase();
RowRec[4] = records.get(i).getMONEY_SENT();
RowRec[5] = records.get(i).getRENT();
RowRec[6] = records.get(i).getPHONE();
RowRec[7] = records.get(i).getGAS();
RowRec[8] = records.get(i).getELECTRICITY();
RowRec[9] = records.get(i).getINTERNET();
RowRec[10] = records.get(i).getOTHER();
tbd.addRow(RowRec);
}
} catch (SQLException e) {
System.out.println(e.toString());
}
}
Basically, you need to create a variable/dynamic query based on the available values
Now, you can do this using something like StringBuilder or even storing each query element in a List or array, but you always end up with the "trailing OR" problem (you need to know when you've got to the last element and not append the "OR" to the String or remove the trailing "OR" from the resulting String). While not difficult, it's just a pain.
However, if you're using Java 8, you can use StringJoiner!
StringJoiner sj = new StringJoiner(" OR ");
String sql = "SELECT B.DATE AS DT, B.EMP_ID, E.FNAME, E.LNAME, MONEY_SENT, RENT, PHONE, GAS, ELECTRICITY, INTERNET, OTHER"
+ " FROM EMPLOYEE E INNER JOIN BILLS B ON E.EMP_ID = B.EMP_ID"
+ " WHERE ";
List values = new ArrayList();
// EmpCode MUST be a Integer, so it can be null
if (EmpCode != null) {
sj.add("B.EMP_ID = ?");
values.add(EmpCode);
}
if (FName != null) {
sj.add("E.FNAME = ?");
values.add(FName);
}
if (LName != null) {
sj.add("E.LNAME = ?");
values.add(LName);
}
if (sDate != null && eDate != null) {
sj.add("DATE BETWEEN ? AND ?");
values.add(sDate);
values.add(eDate);
}
sql += sj.toString();
Connection connect = null;
try (PreparedStatement ps = connect.prepareStatement(sql)) {
for (int index = 0; index < values.size(); index++) {
ps.setObject(index + 1, values.get(index));
}
try (ResultSet rs = ps.executeQuery()) {
if (rs.next()) {
//...
}
}
} catch (SQLException exp) {
exp.printStackTrace();
}
You might also like to have a look at The try-with-resources Statement and have a read through Code Conventions for the Java TM Programming Language, it will make it easier for people to read your code and for you to read others
actually I have 10-30 dummies to get the value from txtCC, but i'd only used 3 dummies for example below..
So how do I get each values and save it directly to my database without using dummy? It's a big deal coz' my code was too large to compile using those dummies..
THANKS for any help..
private void bSaveActionPerformed(java.awt.event.ActionEvent evt)
{
// Save to database
String cc = txtCC.getText();
String delimiter = ",";
String[] temp;
temp = cc.split(delimiter);
for(int i = 0; i < temp.length; i++)
if(i==0) {
txtC1.setText(temp[0]);
txtC2.setText("0");
txtC3.setText("0"); }
else if (i==1) {
txtC1.setText(temp[0]);
txtC2.setText(temp[1]);
txtC3.setText("0"); }
else if (i==2) {
txtC1.setText(temp[0]);
txtC2.setText(temp[1]);
txtC3.setText(temp[2]); }
try {
String cc1 = txtC1.getText(); int CC1 = Integer.parseInt(cc1);
String cc2 = txtC2.getText(); int CC2 = Integer.parseInt(cc2);
String cc3 = txtC3.getText(); int CC3 = Integer.parseInt(cc3);
int opt = JOptionPane.showConfirmDialog(null,"Are you sure you want to save this record? ");
if (opt == 0){
if(!txtC1.getText().equals("0")) {
stmt=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
String sql = "Select * from tbl_liqinfo";
rs = stmt.executeQuery(sql);
rs.next();
rs.moveToInsertRow();
rs.updateInt("CC", CC1);
rs.insertRow();
rs.close();
}
if(!txtC2.getText().equals("0")) {
stmt=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
String sql = "Select * from tbl_liqinfo";
rs = stmt.executeQuery(sql);
rs.next();
rs.moveToInsertRow();
rs.updateInt("CC", CC2);
rs.insertRow();
rs.close();
}
if(!txtC3.getText().equals("0")) {
stmt=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
String sql = "Select * from tbl_liqinfo";
rs = stmt.executeQuery(sql);
rs.next();
rs.moveToInsertRow();
rs.updateInt("CC", CC3);
rs.insertRow();
rs.close();
}
}
}
catch (SQLException err){
JOptionPane.showMessageDialog(FrmEmpLiquidation.this, err.getMessage());
}
}
Instead of using dummies, create simple small methods and make use of it. This will reduce you line of code. and also easy to understand.
private void bSaveActionPerformed(java.awt.event.ActionEvent evt){
// Save to database
String cc = txtCC.getText();
String delimiter = ",";
String[] temp;
temp = cc.split(delimiter);
for(int i = 0; i < temp.length; i++)
insertData(temp[i]);
}
public void insertData(final String data){
txtC1.setText(data);
try {
String cc1 = txtC1.getText(); int CC1 = Integer.parseInt(cc1);
int opt = JOptionPane.showConfirmDialog(null,"Are you sure you want to save this record? ");
if (opt == 0){
if(!txtC1.getText().equals("0")) {
stmt=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
String sql = "Select * from tbl_liqinfo";
rs = stmt.executeQuery(sql);
rs.next();
rs.moveToInsertRow();
rs.updateInt("CC", CC1);
rs.insertRow();
rs.close();
}
}
}
catch (SQLException err){
JOptionPane.showMessageDialog(FrmEmpLiquidation.this, err.getMessage());
}
}
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 7 years ago.
I can not seem to spot where I get NullPointerException Error when call the method fillTable(). fillTable is called from the button what takes in String from a textField.
fillTable is meant to populate a JTable by retrieving Object[][] containing data from a handler class.
private void fillTable(String dataType, String searchBy)
{
String[] columnName = {"module name", "Workshop %", "Lecture %", "Tutorial %", "Average %"};
if(searchBy.startsWith("#"))
{
tableModel.setDataVector(pLSHand.gIStudData(dataType, searchBy), columnName);
table.setModel(tableModel);
}
else
{
tableModel.setDataVector(pLSHand.gNStudData(dataType, searchBy), columnName);
table.setModel(tableModel);
}
table.repaint();
}
Button:
String searchBy = (String)textField.getText();
if(!searchBy.isEmpty())
{
fillTable("Year",searchBy);
}
else
{
}
Method in the Handler class
public Object[][] gIStudData(String dType, String studID)
{
String rQuery = "SELECT * FROM StudAttYear WHERE studentID = '"+ studID +"'";
data = new Object[1][5];
if(dType.equalsIgnoreCase("Semester"))
{
rQuery = "SELECT * FROM StudAttSem WHERE studentID = '"+ studID +"'";
data = new Object[2][5];
}
else if(dType.equalsIgnoreCase("Year"))
{
rQuery = "SELECT * FROM StudAttYear WHERE studentID = '"+ studID +"'";
data = new Object[1][5];
}
else if(dType.equalsIgnoreCase("Week"))
{
rQuery = "SELECT * FROM StudAttWeek WHERE studentID = '"+ studID +"' AND number = '"+ weekNo +"'";
data = new Object[12][5];
}
try{
Class.forName(DRIVER_CLASS);
connection = DriverManager.getConnection( url,"agile", "adila");
statement = connection.createStatement();
results = statement.executeQuery(rQuery);
int i=0;
while(results.next())
{
data[i][0] = results.getString("module");
data[i][1] = results.getString("workshop%");
data[i][2] = results.getString("tutroial%");
data[i][3] = results.getString("lecture%");
data[i][4] = results.getString("avg%");
i++;
}
results.close();
statement.close();
connection.close();
} catch (SQLException sqlException) {
sqlException.printStackTrace();
System.exit(1);
}catch(Exception exception) {
System.err.println("An error happened");
System.exit(1);
}
return data;
}
Using the same technique in other classes and they seem to work.
As stated, pLSHand is not declared elsewhere in your code.