Hello all, I am very new to java, so please ignore if you think this question is stupid. A task has been assigned to me in which I have to extract data from h2 database table with **more than 1 crore rows (SAD) from one table.** And finally show that data into a j table with pagination. What i exactly want is that when the program starts, it extract lets say 1 lac record from database and when user scroll down to the end of first lac records and again extract another lac data from database and so on … It will be best if he goes scroll up, the program doesn’t extract rows which are already extracted. I Hope I explained my problem here very well. Now, After a lot of googling, I found this (https://coderanch.com/t/345383/java/JTable-Paging)very good article which does 90% of what I want, but not with database connection. Can any one tell how to do this ? Here is the sample code : public class PagingTableModel extends AbstractTableModel { private static final int MAX_PAGE_SIZE = 1000000; private static final int LATENCY_MILLIS = 1500; private int dataOffset = 0; private ArrayList<Integer> data = new ArrayList<Integer>(); private SortedSet<Segment> pending = new TreeSet<Segment>(); public int getColumnCount() { return 2; } public String getColumnName(int col) { if (col == 0) return "ANUMBER"; if (col == 1) return "BNUMBER"; return "DATETIME"; } public int getRowCount() { return 10000000; // one million } public Object getValueAt(int row, int col) { ArrayList<Integer> page = data; int pageIndex = row - dataOffset; //JOptionPane.showMessageDialog(null, dataOffset); if (pageIndex < 0 || pageIndex >= page.size()) { System.out.println("object at " + row + " isn't loaded yet"); schedule(row); return ".."; } Object rowObject = page.get(pageIndex); return rowObject; } private void schedule(int offset) { if (isPending(offset)) { return; } int startOffset = Math.max(0, offset - MAX_PAGE_SIZE / 2); int length = offset + MAX_PAGE_SIZE / 2 - startOffset; load(startOffset, length); } private boolean isPending(int offset) { int sz = pending.size(); if (sz == 0) return false; if (sz == 1) { Segment seg = pending.first(); return seg.contains(offset); } Segment lo = new Segment(offset - MAX_PAGE_SIZE, 0); Segment hi = new Segment(offset + 1, 0); for (Segment seg : pending.subSet(lo, hi)) { if (seg.contains(offset)) return true; } return false; } private void load(final int startOffset, final int length) { final Segment seg = new Segment(startOffset, length); pending.add(seg); Runnable fetch = new Runnable() { public void run() { try { Thread.sleep(LATENCY_MILLIS); } catch (InterruptedException ex) { System.out.println("error retrieving page at " + startOffset + ": aborting"); pending.remove(seg); return; } final ArrayList<Integer> page = new ArrayList<Integer>(); for (int j = 0; j < length; j += 1) { page.add(new Integer(j + startOffset)); } SwingUtilities.invokeLater(new Runnable() { public void run() { System.out.println("** loaded " + startOffset + " through " + (startOffset + length - 1)); setData(startOffset, page); pending.remove(seg); } }); } }; new Thread(fetch).start(); } private void setData(int offset, ArrayList<Integer> newData) { // This method must be called from the event dispatch thread. int lastRow = offset + newData.size() - 1; dataOffset = offset; data = newData; fireTableRowsUpdated(offset, lastRow); } public static void main(String[] argv) { JTable tab = new JTable(new PagingTableModel()); JScrollPane sp = new JScrollPane(tab); JFrame f = new JFrame("PagingTableModel"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setContentPane(sp); f.setBounds(30, 50, 1300, 600); f.setVisible(true); } static final class Segment implements Comparable<Segment> { private int base = 0, length = 1; public Segment(int base, int length) { this.base = base; this.length = length; } public boolean contains(int pos) { return (base <= pos && pos < base + length); } public boolean equals(Object o) { return o instanceof Segment && base == ((Segment) o).base && length == ((Segment) o).length; } public int compareTo(Segment other) { int d = base - other.base; if (d != 0) return d; return length - other.length; } } }
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