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JAVA:How to update/refresh Table after changes made into database

I'm new to java and DBMS. I'm trying to update/refresh the JTable after any changes made into the H2 database when user clicks a same button to show JTable and after writing data into database(when write button is clicked). I tried some methods and read some posts but couldn't find anything essential to my program. The code below illustrates my problem.
This is the method used to read from database and show it on JTable
public void readActiveData() throws IOException, InstantiationException, IllegalAccessException, SQLException {
try {
st = conn.createStatement();
} catch (SQLException sqlex) {
JOptionPane.showMessageDialog(null, "Can't connect to DB. " + sqlex);
dispose();
}
try {
rs = st.executeQuery("SELECT * FROM main_data WHERE expirationDate > NOW() + 1;");
rs.beforeFirst();
while (rs.next()) {
int id = rs.getInt(1);
String ovogNer = rs.getString(2);
String regNum = rs.getString(3);
String itemName = rs.getString(4);
String note = rs.getString(5);
int zHemjee = rs.getInt(6);
int hvv = rs.getInt(7);
int hugatsaa = rs.getInt(8);
today = rs.getDate(9);
int totalPay = rs.getInt(10);
expirationDate = rs.getDate(11);
rows++;
}
regData = new Object[rows][11];
Object[] Colheads = {"Бүртгэлийн дугаар", "Овог нэр", "Регистрийн дугаар", "Барьцаа",
"Тэмдэглэл", "Зээлийн хэмжээ", "Хүү (%)", "Хугацаа", "Огноо", "Нийт төлөх", "Дуусах хугацаа"};
rs = st.executeQuery("SELECT * FROM main_data WHERE expirationDate > NOW() + 1;");
for (int i1 = 0; i1 < rows; i1++) {
rs.next();
for (int j1 = 0; j1 < 11; j1++) {
regData[i1][j1] = rs.getString(j1 + 1);
}
}
model = new DefaultTableModel(regData, Colheads);
table = new JTable(model);
int v = ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED;
int h = ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED;
JScrollPane jsp = new JScrollPane(table, v, h);
activeDataPanel.add(jsp);
rs.close();
st.close();
conn.close();
}
And this is the method i'm using to write data into the database
public void writeDataIntoDB() throws InstantiationException, IllegalAccessException {
ResultSet rs = null;
Connection conn = null;
Statement st = null;
PreparedStatement pst = null;
final String URL = "jdbc:h2:~/registDB";
final String USER = "admin";
final String PASS = "password";
LocalDate currentDate = LocalDate.now();
String input = hugatsaaFld.getText();
long addDays = Long.parseLong(input);
expiration = currentDate.plusDays(addDays);
expirationDate = java.sql.Date.valueOf(expiration);
try {
Class.forName("org.h2.Driver").newInstance();
conn = DriverManager.getConnection(URL, USER, PASS);
String sql = "INSERT INTO main_data(ovogNer,regNum,itemName,note,zHemjee,hvv,hugatsaa,date,totalPay,expirationDate)"
+ "VALUES"
+ "(?,?,?,?,?,?,?,?,?,? )";
pst = conn.prepareStatement(sql);
pst.setString(1, getOvogNer());
pst.setString(2, getRegNum());
pst.setString(3, getItemName());
pst.setString(4, getNote());
pst.setInt(5, +getzHemjee());
pst.setInt(6, +getHvv());
pst.setLong(7, +getHugatsaa());
pst.setDate(8, java.sql.Date.valueOf(LocalDate.now()));
pst.setDouble(9, getTotalPay());
pst.setDate(10, expirationDate);
pst.executeUpdate();
pst.close();
conn.close();
} catch (SQLException se) {
JOptionPane.showMessageDialog(null, "Error: " + se);
} catch (ClassNotFoundException ex) {
ex.printStackTrace();
}
}

This question has been answered here
but it comes down to clearing and rerendering your JTable object. i.e. refresh, the post above explains it quite nicely.
Hope you get it right.

Potential memory leak in this Java code that produces out of heap error

I can't find the reason why this piece of code when run for a long time produces an out of memory heap error. It runs constantly for 1-2 days before crashing. Can anyone see anything?
I only call a static function from another class that should not keep any resources open and then the mysql stuff but I close them all.
note: some of the variable names were changed.
public class Application {
public static void main(String ...args) throws InterruptedException, IOException {
Data.connectDb(); //init
try {
List<Integer> written = new ArrayList<>();
Connection con = Data.getConnection();
Statement st = con.createStatement();
ResultSet rs = st.executeQuery("SELECT * FROM table2 LIMIT 500");
while (rs.next()) {
Integer mId = rs.getInt("mId");
written.add(mId);
}
Map<Integer,String> bs = new HashMap<>();
rs = st.executeQuery("SELECT * FROM b");
while (rs.next()) {
bs.put(rs.getInt("bId"),rs.getString("name"));
}
st.close();
rs.close();
while (true) {
List<String> abers = new ArrayList<>();
st = con.createStatement();
rs = st.executeQuery("SELECT * FROM table1 WHERE enabled = 1");
while (rs.next()) {
String email = rs.getString("email");
abers.add(email);
}
rs.close();
st.close();
ArrayList<Map> abs = Aber.getAbs(false);
ArrayList<Map> toDispatch = new ArrayList<>();
arbs.forEach((ab) -> {
Integer mId = (Integer) ab.get("mId");
if (!written.contains(mId)) {
written.add(mId);
toDispatch.add(arb);
Pair hLine = (Pair) ab.get("hLine");
Pair dLine = (Pair) ab.get("dLine");
Pair aLine = (Pair) ab.get("aLine");
//todo write it to the database not caring if it's already there as we have a unique constraint
try (Statement st2 = con.createStatement()) {
String sql = "INSERT INTO table1")";
st2.executeUpdate(sql);
} catch (SQLException e) {
e.printStackTrace();
}
}
});
if (toDispatch.size() >0) {
Email email = new Email();
abes.forEach(arber -> email.addRecipient(aber, aber, Message.RecipientType.BCC));
String HTML = "<h3>Dear subscribers</h3>";
email.setTextHTML(HTML);
new Mailer(
new ServerConfig("mail.name.com", 587, "info#mm.com", "mmpass"),
TransportStrategy.SMTP_TLS
).sendMail(email);
}
Thread.sleep(600000);
}
} catch (SQLException sqle) {
System.out.println(sqle.getMessage());
}
}
}

How to retrieve all the name from MySQL?

I want to retrieve all the name and the number of row from MySQL to java. So far I only able to retrieve the total row number but I only get the last name. What's wrong here ?
StaffManagement.java
adminAPI api= new adminAPI();
try {
int num= api.displayCheckBoxAndLabel();
String allName= api.displayName();
System.out.println(num+allName);
}
adminAPI
public int displayCheckBoxAndLabel() throws Exception // get the number of row
{
int count = 0;
String sql="Select count(*) AS adminID from admin";
DatabaseConnection db = new DatabaseConnection();
Connection conn =db.getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
while(rs.next())
{
count= rs.getInt("adminID");
}
ps.close();
rs.close();
conn.close();
return count ;
}
public String displayName() throws Exception // get all the name
{
String name = null;
String sql="Select name from admin";
DatabaseConnection db = new DatabaseConnection();
Connection conn =db.getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
while(rs.next())
{
name= rs.getString("name");
}
ps.close();
rs.close();
conn.close();
return name ;
}

You currently return a single String, and your method iterates all of the admin names (but terminates after the final row, so that's your result). Instead, build a List of names and return that. You could also use a try-with-resources close to close your Connection, Statement and ResultSet instances. Something like
public List<String> displayName() throws Exception // get all the name
{
String sql = "Select name from admin";
List<String> names = new ArrayList<>();
DatabaseConnection db = new DatabaseConnection();
try (Connection conn = db.getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
ResultSet rs = ps.executeQuery()) {
while (rs.next()) {
names.add(rs.getString("name"));
}
}
return names;
}

This might be helpful
private String names[];
int i = 0;
while (rs.next()) {
names[i] = rs.getString("name");
i++;
}
Then you can use a for loop to return each name in StaffManagement.java

how to get multiple values from one text field with delimiter and save each to database

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());
}
}

Getting Fractions of a Cent

Hey guys I just got my first java job but if things go well I may never need to code again.
What I need to do is connect to a database and apply interest to a large number of transactions.
I am having trouble getting the math to work right on my local machine. This must be correct to within a fraction of a cent. Any ideas? Thanks in advance!
public Connection getConnection() throws SQLException {
Connection conn = null;
Properties connectionProps = new Properties();
connectionProps.put("user", "MY_USER");
connectionProps.put("password", "MY_PASSWORD");
if (this.dbms.equals("mysql")) {
conn = DriverManager.getConnection(
"jdbc:" + this.dbms + "://" +
"YR1F4K3QAS3RV3R" +
":" + this.portNumber + "/",
connectionProps);
} else if (this.dbms.equals("derby")) {
conn = DriverManager.getConnection(
"jdbc:" + this.dbms + ":" +
this.dbName +
";create=true",
connectionProps);
}
System.out.println("Connected to database");
return conn;
}
public static void ApplyInterestToHighVolumeAccounts(Connection con, String dbName, String InterestToApply)
throws SQLException {
Statement stmt = null;
String query = "select * "from " + dbName + ".HighVolumeAccounts";
try {
stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(query);
while (rs.next()) {
String AccountName = rs.getString("AccountName");
int AccountNumber = rs.getInt("AccountNumber");
int Balance = rs.getInt("Balance");
int Interest = InterestToApply
int newBalance = Balance + (Balance * Interest) - (Balance * 0.00000001%)
int AddToRetirement = Balance * 0.000001%
String GetRich = "UPDATE TBL_Accounts SET Balance=Balance" + AddToRetirement + " WHERE AccountName=PrivateAccountInTheCaymens";
ResultSet rs = stmt.executeQuery(GetRich);
String AdjustBalance = "UPDATE TBL_Accounts SET Balance=Balance" + newBalance + " WHERE AccountName=AccountName";
ResultSet rs = stmt.executeQuery(AdjustBalance);
}
} catch (SQLException e ) {
JDBCTutorialUtilities.printSQLException(e);
} finally {
if (stmt != null) { stmt.close(); }
}
}

I think you are really close. BigDecimals would be one way to go.
Use the following code verbatum and you should be fine:
import java.sql.*;
import java.math.BigDecimal;
import java.math.MathContext;
public class adjustaccounts{
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://YR1F4K3QAS3RV3R";
static final String USER = "MY_USER";
static final String PASS = "MY_PASSWORD";
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
try{
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Connecting to database...");
conn = DriverManager.getConnection(DB_URL,USER,PASS);
stmt = conn.createStatement();
String sql;
sql = "SELECT * FROM HighVolumeAccounts";
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()){
//Retrieve by column name
int accountnumber = rs.getInt("AccountNumber");
BigDecimal balance = rs.getBigDecimal("Balance");
String accountname = rs.getString("AccountName");
double pennyshave = 0.000000001;
BigDecimal difference = balance.multiply(new BigDecimal(pennyshave));
//Pad your account
sql = "UPDATE TBL_Accounts SET Balance=Balance +" + difference + " WHERE AccountNumber=00098793302999"; //don't worry about this number, its a Java thing
stmt.executeQuery(sql);
//Adjust the other one.
sql = "UPDATE TBL_Accounts SET Balance=Balance -" + difference + " WHERE AccountName="+ accountname;
stmt.executeQuery(sql);
}
rs.close();
stmt.close();
conn.close();
}catch(SQLException se){
se.printStackTrace();
}catch(Exception e){
e.printStackTrace();
}finally{
try{
if(stmt!=null)
stmt.close();
}catch(SQLException se2){
}
try{
if(conn!=null)
conn.close();
}catch(SQLException se){
se.printStackTrace();
}
}
}
}