Comparing two dates in JAVA

Example:

import java.util.Calendar;
public class MyDate {

public static void main(String[] args) {

Calendar c1=Calendar.getInstance();
c1.set(2009,22,05);

Calendar c2=Calendar.getInstance();
c2.set(2009,23,05);

if(c1.compareTo(c2)<0)
{
// return -1 if date1 is less than date2
System.out.println("1. Date1 is less than date2");
}
else if(c1.compareTo(c2)>0)
{
// return 1 if date1 is greater than date2
System.out.println("1. Date1 is greater than date2");
}
else
{
// return 0 if date1 is equal to date2
System.out.println("1. Date1 is equal to date2");
}

/**
* Compare date with after(), before() and equals() method
*/

if(c1.after(c2))
{
// if date1 is greater than date2
System.out.println("2. Date1 is greater than date2");
}
else if(c1.before(c2))
{
// if date1 is less than date2
System.out.println("2. Date1 is less than date2");
}
else if(c1.equals(c2))
{
// if date1 is equal to date2
System.out.println("2. Date1 is equal to date2");
}
}
}

Example programs of Collection

ArrayList Example :

import java.util.ArrayList;

public class ArrayListExample {

public static void main(String[] args) {

ArrayList arlist=new ArrayList();

// it is return type of ArrayList

arlist.add("First Element"); // adding element in ArrayList
arlist.add("Second Element");
arlist.add("Third Element");
arlist.add("forth Element");
arlist.add("fifth Element");

// add element with index for fix order

arlist.add(2, "Fixed Order of Element");

// arlist.size() inform number of elements in ArrayList
System.out.println("ArrayList Size :"+arlist.size());

// get elements of ArrayList
for(int i=0;i hs=new HashSet();

// duplicate element is not permitted
hs.add("b");
hs.add("a");
hs.add("c");
hs.add("d");
hs.add("d");

Iterator it=hs.iterator();

while(it.hasNext())
{
String value =(String)it.next();

System.out.println("Value :"+value);
}

//find size of hashSet

System.out.println("Size :"+hs.size());

// Remove element from hashSet :
hs.remove("d");

// To remove all object from hashSet
hs.clear();
}
}


HashTableExample :

import java.util.Hashtable;
import java.util.Enumeration;

public class HashTableExample {

public static void main(String[] args) {

Hashtable hTable=new Hashtable();

//adding or set items in Hashtable by put method key and value pair
hTable.put(new Integer(2), "Two");
hTable.put(new Integer(1), "One");
hTable.put(new Integer(4), "Four");
hTable.put(new Integer(3), "Three");
hTable.put(new Integer(5), "Five");

// Get Hashtable Enumeration to get key and value
Enumeration em=hTable.keys();

while(em.hasMoreElements())
{
//nextElement is used to get key of Hashtable
int key = (Integer)em.nextElement();

//get is used to get value of key in Hashtable
String value=(String)hTable.get(key);

System.out.println("Key :"+key+" value :"+value);
}
}
}




HashMapExample :

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class HashMapExample {

public static void main(String[] args) {

HashMap hm=new HashMap();

// adding or set elements in HashMap by put method key and value pair
hm.put(new Integer(2), "Two");
hm.put(new Integer(1), "One");
hm.put(new Integer(3), "Three");
hm.put(new Integer(4), "Four");

// Get hashmap in Set interface to get key and value
Set s=hm.entrySet();

// Move next key and value of HashMap by iterator
Iterator it=s.iterator();

while(it.hasNext())
{
// key=value separator this by Map.Entry to get key and value
Map.Entry m =(Map.Entry)it.next();

// getKey is used to get key of HashMap
int key=(Integer)m.getKey();

// getValue is used to get value of key in HashMap
String value=(String)m.getValue();

System.out.println("Key :"+key);
System.out.println("value :"+value);
}
}
}

TreeSetExample :

import java.util.Iterator;
import java.util.TreeSet;

public class TreeSetExample {

public static void main(String[] args) {

// TreeSet return in ordered elements
TreeSet ts=new TreeSet();

ts.add("b");
ts.add("a");
ts.add("d");
ts.add("c");

// get element in Iterator
Iterator it=ts.iterator();

// get descending order of elements
//Iterator it=ts.descendingIterator();

while(it.hasNext())
{
String value=(String)it.next();

System.out.println("Value :"+value);
}
}
}

How to make JTable cell not Editable?

Implement the isEditable() method in your table model and return false and you table will not be editable.

Example:

public class MyTableModel extends AbstractTableModel{

public void isEditable()
{
return false;
}
}

Then you have a table and you set its model to a MyTableModel object
ex.

JTable table = new JTable();
table.setModel(new MyTableModel());

Write Text into File

import java.io.*;

public class WriteTextFileExample{
public static void main(String[] args)throws IOException{
BufferedWriter output = null;
String text = Amirtharaj;
// if 2nd arg is true then the file content append
FileWriter fstream = new FileWriter("write.txt", true);
output = new BufferedWriter(fstream);
output.write(text);
output.close()
}
}

Adding a external jar to an RCP application

Open plug-in.xml
Go to Runtime tab.
Click on 'Add...' button in the Classpath section
Add your external jar

As a result my MANIFEST.MF now has the entry
Bundle-ClassPath: lib/myjar.jar,

while my .classpath has the entry
classpathentry kind="lib" path="lib/myjar.jar"

DragandDrop in JTable

TransferHandler is used to handle the transfer of a Transferable to and from Swing components. The Transferable is used to represent data that is exchanged via a cut, copy, or paste to/from a clipboard. It is also used in drag-and-drop operations to represent a drag from a component, and a drop to a component. Swing provides functionality that automatically supports cut, copy, and paste keyboard bindings that use the functionality provided by an implementation of this class. Swing also provides functionality that automatically supports drag and drop that uses the functionality provided by an implementation of this class. The Swing developer can concentrate on specifying the semantics of a transfer primarily by setting the transferHandler property on a Swing component.

This class is implemented to provide a default behavior of transferring a component property simply by specifying the name of the property in the constructor. For example, to transfer the foreground color from one component to another either via the clipboard or a drag and drop operation a TransferHandler can be constructed with the string "foreground". The built in support will use the color returned by getForeground as the source of the transfer, and setForeground for the target of a transfer.


For Example for JTable:


import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.*;
import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.event.*;
import java.io.IOException;

public class DragandDrop extends JFrame {

public DragandDrop() {
setTitle("DnD Demo");
JTextArea tips = new JTextArea("1. Select a row in Table A. " +
"Press the row again and drag. \n " +
"As you drag the cursor icon over Table B, the row that is currently under the cursor highlights " +
"? the new data will be inserted after the selected row. \n " +
"Drop the row onto Table B. Note that the row has been removed from Table A, " +
"and now appears in Table B. \n" +
"2. Select two rows from Table A and drop onto Table B. " +
"Now there are two new rows in Table B. ");
tips.setEditable(false);
tips.setBackground(new Color(255, 255, 204));
tips.setBorder(new LineBorder(Color.orange, 5));
getContentPane().add(tips, BorderLayout.NORTH);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel(new GridLayout(2, 1));
panel.add(createTable("Table A"));
panel.add(createTable("Table B"));
getContentPane().add(panel, BorderLayout.CENTER);
pack();
setLocationRelativeTo(null);
}

private JPanel createTable(String tableId) {
DefaultTableModel model = new DefaultTableModel();
model.addColumn("Column 0");
model.addColumn("Column 1");
model.addColumn("Column 2");
model.addColumn("Column 3");
model.addRow(new String[]{tableId + " 00", tableId + " 01", tableId + " 02", tableId + " 03"});
model.addRow(new String[]{tableId + " 10", tableId + " 11", tableId + " 12", tableId + " 13"});
model.addRow(new String[]{tableId + " 20", tableId + " 21", tableId + " 22", tableId + " 23"});
model.addRow(new String[]{tableId + " 30", tableId + " 31", tableId + " 32", tableId + " 33"});
model.addRow(new String[]{tableId + " 40", tableId + " 41", tableId + " 42", tableId + " 43"});
model.addRow(new String[]{tableId + " 50", tableId + " 51", tableId + " 52", tableId + " 53"});
model.addRow(new String[]{tableId + " 60", tableId + " 61", tableId + " 62", tableId + " 63"});
model.addRow(new String[]{tableId + " 70", tableId + " 71", tableId + " 72", tableId + " 73"});
JTable table = new JTable(model);
table.getTableHeader().setReorderingAllowed(false);
table.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
JScrollPane scrollPane = new JScrollPane(table);
scrollPane.setPreferredSize(new Dimension(400, 100));
table.setDragEnabled(true);
table.setTransferHandler(new TableTransferHandler());
scrollPane.getViewport().setTransferHandler(new ViewportTransferHandler());
JPanel panel = new JPanel();
panel.add(scrollPane);
panel.setBorder(BorderFactory.createTitledBorder(tableId));
return panel;
}

public static void main(String[] args) {
new DragandDrop().setVisible(true);
}

abstract class StringTransferHandler extends TransferHandler {

protected abstract String exportString(JComponent c);

protected abstract void importString(JComponent c, String str);

protected abstract void cleanup(JComponent c, boolean remove);

protected Transferable createTransferable(JComponent c) {
return new StringSelection(exportString(c));
}

public int getSourceActions(JComponent c) {
return COPY_OR_MOVE;
}

public boolean importData(JComponent c, Transferable t) {
if (canImport(c, t.getTransferDataFlavors())) {
try {
String str = (String) t.getTransferData(DataFlavor.stringFlavor);
importString(c, str);
return true;
} catch (UnsupportedFlavorException ufe) {
} catch (IOException ioe) {
}
}
return false;
}

protected void exportDone(JComponent c, Transferable data, int action) {
cleanup(c, action == MOVE);
}

public boolean canImport(JComponent c, DataFlavor[] flavors) {
for (int ndx = 0; ndx < flavors.length; ndx++) {
if (DataFlavor.stringFlavor.equals(flavors[ndx])) {
return true;
}
}
return false;
}
}

class TableTransferHandler extends StringTransferHandler {

public JTable target;
public int[] rows = null;
public int addIndex = -1; //Location where items were added

public int addCount = 0; //Number of items added.


protected String exportString(JComponent c) {
JTable table = (JTable) c;
rows = table.getSelectedRows();
int colCount = table.getColumnCount();
StringBuffer buff = new StringBuffer();
for (int ndx = 0; ndx < rows.length; ndx++) {
for (int j = 0; j < colCount; j++) {
Object val = table.getValueAt(rows[ndx], j);
buff.append(val == null ? "" : val.toString());
if (j != colCount - 1) {
buff.append(",");
}
}
if (ndx != rows.length - 1) {
buff.append("\n");
}
}
return buff.toString();
}

protected void importString(JComponent c, String str) {
target = (JTable) c;
DefaultTableModel model = (DefaultTableModel) target.getModel();
int index = target.getSelectedRow();
//Prevent the user from dropping data back on itself.
//For example, if the user is moving rows #4,#5,#6 and #7 and
//attempts to insert the rows after row #5, this would
//be problematic when removing the original rows.
//So this is not allowed.
if (rows != null && index >= rows[0] - 1 &&
index <= rows[rows.length - 1]) {
rows = null;
return;
}
int max = model.getRowCount();
if (index < 0) {
index = max;
} else {
index++;
if (index > max) {
index = max;
}
}
addIndex = index;
String[] values = str.split("\n");
addCount = values.length;
int colCount = target.getColumnCount();
for (int ndx = 0; ndx < values.length; ndx++) {
model.insertRow(index++, values[ndx].split(","));
}
//If we are moving items around in the same table, we
//need to adjust the rows accordingly, since those
//after the insertion point have moved.
if (rows != null && addCount > 0) {
for (int ndx = 0; ndx < rows.length; ndx++) {
if (rows[ndx] > addIndex) {
rows[ndx] += addCount;
}
}
}
}

protected void cleanup(JComponent c, boolean remove) {
JTable source = (JTable) c;
if (remove && rows != null) {
DefaultTableModel model =
(DefaultTableModel) source.getModel();
for (int ndx = rows.length - 1; ndx >= 0; ndx--) {
model.removeRow(rows[ndx]);
}
}
rows = null;
addCount = 0;
addIndex = -1;
}
}

class ViewportTransferHandler extends TransferHandler {

private JComponent getView(JComponent comp) {
JViewport viewport = (JViewport) comp;
return (JComponent) viewport.getView();
}

public boolean canImport(JComponent comp, DataFlavor[] transferFlavors) {
JComponent view = getView(comp);
return view.getTransferHandler().canImport(view, transferFlavors);
}

public void exportAsDrag(JComponent comp, InputEvent e, int action) {
JComponent view = getView(comp);
view.getTransferHandler().exportAsDrag(view, e, action);
}

public void exportToClipboard(JComponent comp, Clipboard clip, int action) {
JComponent view = getView(comp);
view.getTransferHandler().exportToClipboard(view, clip, action);
}

public int getSourceActions(JComponent c) {
JComponent view = getView(c);
return view.getTransferHandler().getSourceActions(view);
}

public boolean importData(JComponent comp, Transferable t) {
JComponent view = getView(comp);
return view.getTransferHandler().importData(view, t);
}
}
}

Java and Swing Tips

How to check File exists or not?

File f = new File("Path name of the file");
if(f.exists())
{
System.out.println("File Exists");
}

How to create new Folder?

File newFolder = new File("Path name of the Folder");
nf.mkdir(newFolder);

How to popup Dialog screen center?

JDialog dg = new JDialog(null);
dg.setLocationRelativeTo(null);

// Dialog will popup on frame center
JFrame f = new JFrame("Owner");
JDialog dg = new JDialog(f);
dg.setLocationRelativeTo(f);

(or)

// centers the dialog within the screen [1.1]
//  (put that in the Frame/Dialog class)
public void centerScreen() {
 Dimension dim = getToolkit().getScreenSize();
 Rectangle abounds = getBounds();
 setLocation((dim.width - abounds.width) / 2,
     (dim.height - abounds.height) / 2);
 super.setVsible(true);
 requestFocus();
}

// centers the dialog within the parent container [1.1]
//  (put that in the Dialog class)
public void centerParent () {
 int x;
 int y;

 // Find out our parent
 Container myParent = getParent();
 Point topLeft = myParent.getLocationOnScreen();
 Dimension parentSize = myParent.getSize();

 Dimension mySize = getSize();

 if (parentSize.width > mySize.width)
   x = ((parentSize.width - mySize.width)/2) + topLeft.x;
 else
   x = topLeft.x;
 
 if (parentSize.height > mySize.height)
   y = ((parentSize.height - mySize.height)/2) + topLeft.y;
 else
   y = topLeft.y;
 
 setLocation (x, y);
 super.setVsible(true);
 requestFocus();
} 

How to check filename consists of any special character using ascii values?

private boolean isValidFilename(String filename) {
char beginchar = filename.toCharArray()[0];
int aV = beginchar;
if (!((aV > 64 && aV <> 96 && aV < j =" 0;" fchar =" cArrforfile[j];" av =" fChar;"> 64 && aV <> 96 && aV <> 47 && aV < 59)|| (aV == 95))) {
System.out.println("Filename must not contain any special character");
return false;
}
}
return true;
}