Develop Reference

How to fix the error on java.lang.ArrayIndexOutOfBoundsException: 4 >= 4

My program is used to display the textfield values and date to a table in java and saves the table value to MySQL database. The textfiled and dateChooser data is displayed in the table and saved in one click of a button
DefaultTableModel model = (DefaultTableModel) jTable2.getModel();
model.addRow(new Object[]
{((JTextField) invo_date.getDateEditor().getUiComponent()).getText(),
((JTextField) invo_date1.getDateEditor().getUiComponent()).getText(),
dec.getText(), BL.getText()});
conn = JavaDb.ConnectDB();
int p = 0;
if (p == 0) {
try {
int rows = jTable2.getRowCount();
String queryco = "update into status(date, to_date, description, containers) values( ?,?,?,?)";
pst = conn.prepareStatement(queryco);
for (int row = 0; row < rows; row++) {
String datee = (String) jTable2.getValueAt(row, 0);
String mpakadates = (String) jTable2.getValueAt(row, 1);
String descri = (String) jTable2.getValueAt(row, 2);
String total = (String) jTable2.getValueAt(row, 3);
String container = (String) jTable2.getValueAt(row, 4);
pst.setString(1, datee);
pst.setString(2, mpakadates);
pst.setString(3, descri);
pst.setString(4, total);
pst.setString(5, container);
pst.addBatch();
}
pst.executeBatch();
pst.execute();
JOptionPane.showMessageDialog(this, "Data Saved Successfully");
st.close();
} catch (Exception e) {
System.err.println("Got an exception! " + e);
System.err.println(e.getMessage());
}
}

how to insert jtable only one column data into DB mysql?

I need to insert only one column data from jtable to DB mysql,I found a way to do it but i'm facing a problem which occur when i inserted less data than expected eg: insert 2 rows instead of 3 rows; Error:java.lang.arrayindexoutofboundsexception 2>=2
How do I get rid of this ?
You can check out my code down ...Thanks
try
{
//String product3 = "null";
int rows = jTable1.getRowCount();
int cols = jTable1.getColumnCount();
String salesql = "insert into salling(orderid,saledate,prod1,prod2,prod3,tax,subtotal,total) values(?,?,?,?,?,?,?,?)";
pst = conn.prepareStatement(salesql);
pst.setString(1, jTextFieldOrderNo.getText());
pst.setString(2, jTextFieldDate.getText());
for(int row =0; row <= rows; row++)
{
String product1 = (String)jTable1.getValueAt(0, 0);
String product2 = (String)jTable1.getValueAt(1, 0);
String product3 = (String)jTable1.getValueAt(2, 0);
// String product3 = (String)jTable1
pst.setString(3, product1);
pst.setString(4, product2);
pst.setString(5, product3);
}
pst.setString(6, jTextFieldTax.getText());
pst.setString(7, jTextFieldSuTotal.getText());
pst.setString(8, jTextFieldTotal.getText());
pst.execute();
JOptionPane.showMessageDialog(null, "Data saved...");
}catch(Exception e)
{
JOptionPane.showMessageDialog(null, e);
}
}

How do I update thousands of records into MySQL DB in milliseconds

I want to update about 10K records into MySQL DB in less than a second. I have written below code which takes about 6-8 seconds to update a list of records into DB.
public void updateResultList(List<?> list) {
String user = "root";
String pass = "root";
String jdbcUrl = "jdbc:mysql://12.1.1.1/db_1?useSSL=false";
String driver = "com.mysql.jdbc.Driver";
PreparedStatement pstm = null;
try {
Class.forName(driver);
Connection myConn = DriverManager.getConnection(jdbcUrl, user, pass);
myConn.setAutoCommit(false);
for(int i=0; i<list.size(); i++) {
Object[] row = (Object[]) list.get(i);
int candidateID = Integer.valueOf(String.valueOf(row[0]));
String result = String.valueOf(row[14]);
int score = Integer.valueOf(String.valueOf(row[19]));
String uploadState = (String) row[20];
String sql = "UPDATE personal_info SET result = ?, score = ?, uploadState = ? "
+ " WHERE CandidateID = ?";
pstm = (PreparedStatement) myConn.prepareStatement(sql);
pstm.setString(1, result);
pstm.setInt(2, score);
pstm.setString(3, uploadState);
pstm.setInt(4, candidateID);
pstm.addBatch();
pstm.executeBatch();
}
myConn.commit();
myConn.setAutoCommit(true);
pstm.close();
myConn.close();
}
catch (Exception exc) {
exc.printStackTrace();
try {
throw new ServletException(exc);
} catch (ServletException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Please let me know your inputs to optimize this code for performance improvement.

First, you need to init prepareStatement only once,you need to init it before the for loop
Second,you should avoid excute pstm.executeBatch(); for every loop it will cost much more resource,you need to execute it for a specified amount,such as 100,500 or more,also do not execute it outside the for loop for only once,due to it will cost more memory resource
Class.forName(driver);
Connection myConn = DriverManager.getConnection(jdbcUrl, user, pass);
myConn.setAutoCommit(false);
String sql = "UPDATE personal_info SET result = ?, score = ?, uploadState = ? "
+ " WHERE CandidateID = ?";
pstm = (PreparedStatement) myConn.prepareStatement(sql);
for(int i=0; i<list.size(); i++) {
Object[] row = (Object[]) list.get(i);
int candidateID = Integer.valueOf(String.valueOf(row[0]));
String result = String.valueOf(row[14]);
int score = Integer.valueOf(String.valueOf(row[19]));
String uploadState = (String) row[20];
pstm.setString(1, result);
pstm.setInt(2, score);
pstm.setString(3, uploadState);
pstm.setInt(4, candidateID);
pstm.addBatch();
if(i%500==0){//execute when it meet a specified amount
pstm.executeBatch();
}
}
pstm.executeBatch();
myConn.commit();
myConn.setAutoCommit(true);

Rather than batching the individual UPDATEs, you could batch INSERTs into a temporary table with rewriteBatchedStatements=true and then use a single UPDATE statement to update the main table. On my machine with a local MySQL instance, the following code takes about 2.5 seconds ...
long t0 = System.nanoTime();
conn.setAutoCommit(false);
String sql = null;
sql = "UPDATE personal_info SET result=?, score=?, uploadState=? WHERE CandidateID=?";
PreparedStatement ps = conn.prepareStatement(sql);
String tag = "X";
for (int i = 1; i <= 10000; i++) {
ps.setString(1, String.format("result_%s_%d", tag, i));
ps.setInt(2, 200000 + i);
ps.setString(3, String.format("state_%s_%d", tag, i));
ps.setInt(4, i);
ps.addBatch();
}
ps.executeBatch();
conn.commit();
System.out.printf("%d ms%n", (System.nanoTime() - t0) / 1000000);
... while this version takes about 1.3 seconds:
long t0 = System.nanoTime();
conn.setAutoCommit(false);
String sql = null;
Statement st = conn.createStatement();
st.execute("CREATE TEMPORARY TABLE tmp (CandidateID INT, result VARCHAR(255), score INT, uploadState VARCHAR(255))");
sql = "INSERT INTO tmp (result, score, uploadState, CandidateID) VALUES (?,?,?,?)";
PreparedStatement ps = conn.prepareStatement(sql);
String tag = "Y";
for (int i = 1; i <= 10000; i++) {
ps.setString(1, String.format("result_%s_%d", tag, i));
ps.setInt(2, 400000 + i);
ps.setString(3, String.format("state_%s_%d", tag, i));
ps.setInt(4, i);
ps.addBatch();
}
ps.executeBatch();
sql =
"UPDATE personal_info pi INNER JOIN tmp ON tmp.CandidateID=pi.CandidateID "
+ "SET pi.result=tmp.result, pi.score=tmp.score, pi.uploadState=tmp.uploadState";
st.execute(sql);
conn.commit();
System.out.printf("%d ms%n", (System.nanoTime() - t0) / 1000000);

your pstm.executeBatch() should be after forloop
refer How to insert List into database

Insert Mulitple Row Data from Jtable into database

I am trying to save Multiple row data from JTable into Database, Here is my code for reference:
try{
int rows=tblCO2.getRowCount();
for(int row = 0; row<rows; row++)
{
String coitemname = (String)tblCO2.getValueAt(row, 0);
String cocateg = (String)tblCO2.getValueAt(row, 1);
String codesc = (String)tblCO2.getValueAt(row, 2);
String coloc = (String)tblCO2.getValueAt(row, 3);
String coitemtagno = (String)tblCO2.getValueAt(row, 4);
try
{
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/iotams",user,pass);
conn.setAutoCommit(false);
String queryco = "Insert into tblcheckout(CheckoutID,ItemTagNo,ItemName,Category,Description,Location) values (?,?,?,?,?)";
pst = conn.prepareStatement(queryco);
pst.setString(1, coitemname);
pst.setString(2, cocateg);
pst.setString(3, codesc);
pst.setString(4, coloc);
pst.setString(5, coitemtagno);
pst.addBatch();
}
catch(Exception e)
{
}
}
pst.executeBatch();
conn.commit();
}
catch(Exception e){
JOptionPane.showMessageDialog(this,e.getMessage());
}
The Problem is, it is only inserting one row data into database. Can someone please help me? :( thanks!

Remove following line codes from loop and place before loop
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/iotams",user,pass);
conn.setAutoCommit(false);
String queryco = "Insert into tblcheckout(CheckoutID,ItemTagNo,ItemName,Category,Description,Location) values (?,?,?,?,?)";
pst = conn.prepareStatement(queryco);
Example: Replace your code by following code
try{
int rows=tblCO2.getRowCount();
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/iotams",user,pass);
conn.setAutoCommit(false);
String queryco = "Insert into tblcheckout(CheckoutID,ItemTagNo,ItemName,Category,Description,Location) values (?,?,?,?,?)";
pst = conn.prepareStatement(queryco);
for(int row = 0; row<rows; row++)
{
String coitemname = (String)tblCO2.getValueAt(row, 0);
String cocateg = (String)tblCO2.getValueAt(row, 1);
String codesc = (String)tblCO2.getValueAt(row, 2);
String coloc = (String)tblCO2.getValueAt(row, 3);
String coitemtagno = (String)tblCO2.getValueAt(row, 4);
pst.setString(1, coitemname);
pst.setString(2, cocateg);
pst.setString(3, codesc);
pst.setString(4, coloc);
pst.setString(5, coitemtagno);
pst.addBatch();
}
pst.executeBatch();
conn.commit();
}
catch(Exception e){
JOptionPane.showMessageDialog(this,e.getMessage());
}
Then run it think it work.
For Batch insert example is here https://my.vertica.com/docs/5.0/HTML/Master/14878.htm

the code above is not able to run in netbeans ,
However I made a version for netbeans.
try{
int rows=jTable1.getRowCount();
for(int row = 0; row<rows; row++)
{
Integer qty = (Integer)jTable1.getValueAt(row, 0);
Double unitprice = (Double) jTable1.getValueAt(row, 1);
String description = (String)jTable1.getValueAt(row, 2);
Double total = (Double)jTable1.getValueAt(row, 3);
String queryco = "Insert into invoice(qty,unitprice,description,total) values ('"+qty+"','"+unitprice+"','"+description+"','"+total+"')";
pst = conn.prepareStatement(queryco);
pst.execute();
}
JOptionPane.showMessageDialog(null, "Successfully Save");
}
catch(Exception e){
JOptionPane.showMessageDialog(this,e.getMessage());
}

Retrieve column names from java.sql.ResultSet

With java.sql.ResultSet is there a way to get a column's name as a String by using the column's index? I had a look through the API doc but I can't find anything.

You can get this info from the ResultSet metadata. See ResultSetMetaData
e.g.
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
String name = rsmd.getColumnName(1);
and you can get the column name from there. If you do
select x as y from table
then rsmd.getColumnLabel() will get you the retrieved label name too.

In addition to the above answers, if you're working with a dynamic query and you want the column names but do not know how many columns there are, you can use the ResultSetMetaData object to get the number of columns first and then cycle through them.
Amending Brian's code:
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
// The column count starts from 1
for (int i = 1; i <= columnCount; i++ ) {
String name = rsmd.getColumnName(i);
// Do stuff with name
}

You can use the the ResultSetMetaData (http://java.sun.com/javase/6/docs/api/java/sql/ResultSetMetaData.html) object for that, like this:
ResultSet rs = stmt.executeQuery("SELECT * FROM table");
ResultSetMetaData rsmd = rs.getMetaData();
String firstColumnName = rsmd.getColumnName(1);

This question is old and so are the correct previous answers. But what I was looking for when I found this topic was something like this solution. Hopefully it helps someone.
// Loading required libraries
import java.util.*;
import java.sql.*;
public class MySQLExample {
public void run(String sql) {
// JDBC driver name and database URL
String JDBC_DRIVER = "com.mysql.jdbc.Driver";
String DB_URL = "jdbc:mysql://localhost/demo";
// Database credentials
String USER = "someuser"; // Fake of course.
String PASS = "somepass"; // This too!
Statement stmt = null;
ResultSet rs = null;
Connection conn = null;
Vector<String> columnNames = new Vector<String>();
try {
// Register JDBC driver
Class.forName(JDBC_DRIVER);
// Open a connection
conn = DriverManager.getConnection(DB_URL, USER, PASS);
// Execute SQL query
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
if (rs != null) {
ResultSetMetaData columns = rs.getMetaData();
int i = 0;
while (i < columns.getColumnCount()) {
i++;
System.out.print(columns.getColumnName(i) + "\t");
columnNames.add(columns.getColumnName(i));
}
System.out.print("\n");
while (rs.next()) {
for (i = 0; i < columnNames.size(); i++) {
System.out.print(rs.getString(columnNames.get(i))
+ "\t");
}
System.out.print("\n");
}
}
} catch (Exception e) {
System.out.println("Exception: " + e.toString());
}
finally {
try {
if (rs != null) {
rs.close();
}
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
} catch (Exception mysqlEx) {
System.out.println(mysqlEx.toString());
}
}
}
}

SQLite 3
Using getMetaData();
DatabaseMetaData md = conn.getMetaData();
ResultSet rset = md.getColumns(null, null, "your_table_name", null);
System.out.println("your_table_name");
while (rset.next())
{
System.out.println("\t" + rset.getString(4));
}
EDIT: This works with PostgreSQL as well

import java.sql.*;
public class JdbcGetColumnNames {
public static void main(String args[]) {
Connection con = null;
Statement st = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/komal", "root", "root");
st = con.createStatement();
String sql = "select * from person";
rs = st.executeQuery(sql);
ResultSetMetaData metaData = rs.getMetaData();
int rowCount = metaData.getColumnCount();
System.out.println("Table Name : " + metaData.getTableName(2));
System.out.println("Field \tDataType");
for (int i = 0; i < rowCount; i++) {
System.out.print(metaData.getColumnName(i + 1) + " \t");
System.out.println(metaData.getColumnTypeName(i + 1));
}
} catch (Exception e) {
System.out.println(e);
}
}
}
Table Name : person
Field DataType
id VARCHAR
cname VARCHAR
dob DATE

while (rs.next()) {
for (int j = 1; j < columncount; j++) {
System.out.println( rsd.getColumnName(j) + "::" + rs.getString(j));
}
}

When you need the column names, but do not want to grab entries:
PreparedStatement stmt = connection.prepareStatement("SHOW COLUMNS FROM `yourTable`");
ResultSet set = stmt.executeQuery();
//store all of the columns names
List<String> names = new ArrayList<>();
while (set.next()) { names.add(set.getString("Field")); }
NOTE: Only works with MySQL

The SQL statements that read data from a database query return the data in a result set. The SELECT statement is the standard way to select rows from a database and view them in a result set. The **java.sql.ResultSet** interface represents the result set of a database query.
Get methods: used to view the data in the columns of the current row
being pointed to by the cursor.
Using MetaData of a result set to fetch the exact column count
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
int numberOfColumns = rsmd.getColumnCount();
boolean b = rsmd.isSearchable(1);
http://docs.oracle.com/javase/7/docs/api/java/sql/ResultSetMetaData.html
and further more to bind it to data model table
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
try {
//STEP 2: Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");
//STEP 3: Open a connection
System.out.println("Connecting to a selected database...");
conn = DriverManager.getConnection(DB_URL, USER, PASS);
System.out.println("Connected database successfully...");
//STEP 4: Execute a query
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql = "SELECT id, first, last, age FROM Registration";
ResultSet rs = stmt.executeQuery(sql);
//STEP 5: Extract data from result set
while(rs.next()){
//Retrieve by column name
int id = rs.getInt("id");
int age = rs.getInt("age");
String first = rs.getString("first");
String last = rs.getString("last");
//Display values
System.out.print("ID: " + id);
System.out.print(", Age: " + age);
System.out.print(", First: " + first);
System.out.println(", Last: " + last);
}
rs.close();
} catch(SQLException se) {
//Handle errors for JDBC
se.printStackTrace();
} catch(Exception e) {
//Handle errors for Class.forName
e.printStackTrace();
} finally {
//finally block used to close resources
try {
if(stmt!=null)
conn.close();
} catch(SQLException se) {
} // do nothing
try {
if(conn!=null)
conn.close();
} catch(SQLException se) {
se.printStackTrace();
} //end finally try
}//end try
System.out.println("Goodbye!");
}//end main
//end JDBCExample
very nice tutorial here : http://www.tutorialspoint.com/jdbc/
ResultSetMetaData meta = resultset.getMetaData(); // for a valid resultset object after executing query
Integer columncount = meta.getColumnCount();
int count = 1 ; // start counting from 1 always
String[] columnNames = null;
while(columncount <=count) {
columnNames [i] = meta.getColumnName(i);
}
System.out.println (columnNames.size() ); //see the list and bind it to TableModel object. the to your jtbale.setModel(your_table_model);

#Cyntech is right.
Incase your table is empty and you still need to get table column names you can get your column as type Vector,see the following:
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
Vector<Vector<String>>tableVector = new Vector<Vector<String>>();
boolean isTableEmpty = true;
int col = 0;
while(rs.next())
{
isTableEmpty = false; //set to false since rs.next has data: this means the table is not empty
if(col != columnCount)
{
for(int x = 1;x <= columnCount;x++){
Vector<String> tFields = new Vector<String>();
tFields.add(rsmd.getColumnName(x).toString());
tableVector.add(tFields);
}
col = columnCount;
}
}
//if table is empty then get column names only
if(isTableEmpty){
for(int x=1;x<=colCount;x++){
Vector<String> tFields = new Vector<String>();
tFields.add(rsmd.getColumnName(x).toString());
tableVector.add(tFields);
}
}
rs.close();
stmt.close();
return tableVector;

ResultSet rsTst = hiSession.connection().prepareStatement(queryStr).executeQuery();
ResultSetMetaData meta = rsTst.getMetaData();
int columnCount = meta.getColumnCount();
// The column count starts from 1
String nameValuePair = "";
while (rsTst.next()) {
for (int i = 1; i < columnCount + 1; i++ ) {
String name = meta.getColumnName(i);
// Do stuff with name
String value = rsTst.getString(i); //.getObject(1);
nameValuePair = nameValuePair + name + "=" +value + ",";
//nameValuePair = nameValuePair + ", ";
}
nameValuePair = nameValuePair+"||" + "\t";
}

If you want to use spring jdbctemplate and don't want to deal with connection staff, you can use following:
jdbcTemplate.query("select * from books", new RowCallbackHandler() {
public void processRow(ResultSet resultSet) throws SQLException {
ResultSetMetaData rsmd = resultSet.getMetaData();
for (int i = 1; i <= rsmd.getColumnCount(); i++ ) {
String name = rsmd.getColumnName(i);
// Do stuff with name
}
}
});

U can get column name and value from resultSet.getMetaData();
This code work for me:
Connection conn = null;
PreparedStatement preparedStatement = null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
conn = MySQLJDBCUtil.getConnection();
preparedStatement = conn.prepareStatement(sql);
if (params != null) {
for (int i = 0; i < params.size(); i++) {
preparedStatement.setObject(i + 1, params.get(i).getSqlValue());
}
ResultSet resultSet = preparedStatement.executeQuery();
ResultSetMetaData md = resultSet.getMetaData();
while (resultSet.next()) {
int counter = md.getColumnCount();
String colName[] = new String[counter];
Map<String, Object> field = new HashMap<>();
for (int loop = 1; loop <= counter; loop++) {
int index = loop - 1;
colName[index] = md.getColumnLabel(loop);
field.put(colName[index], resultSet.getObject(colName[index]));
}
rows.add(field);
}
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (preparedStatement != null) {
try {
preparedStatement.close();
}catch (Exception e1) {
e1.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
return rows;

I know, this question is already answered but probably somebody like me needs to access a column name from DatabaseMetaData by label instead of index:
ResultSet resultSet = null;
DatabaseMetaData metaData = null;
try {
metaData = connection.getMetaData();
resultSet = metaData.getColumns(null, null, tableName, null);
while (resultSet.next()){
String name = resultSet.getString("COLUMN_NAME");
}
}