Vector

 

public class Vector<E>
    extends AbstractList<E>
        implements List<E>, RandomAccess, Cloneable, Serializable

 

• The Vector class implements a growable array of objects where the size of the vector can grow or shrink as needed dynamically.
• Like an array, it contains components that can be accessed using an integer index.
• An application can increase the capacity of a vector before inserting a large number of components; this reduces the amount of incremental reallocation.

 

Below is a Vector Example showing how collections are manipulated using a Vector

import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.Enumeration;
import java.util.NoSuchElementException;
import java.util.Vector;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;

 public class VectorDemo extends JFrame 
 {
	 private JLabel jlbString = new JLabel( "Enter a string" );
	 public VectorDemo()
	 {
		 super( "Vector class demo" );
// Made final as it can be accessed by inner classes
		 final JLabel jlbStatus = new JLabel();
		 Container contentPane = getContentPane();
		 final Vector vector = new Vector( 1 );
		 
		 contentPane.setLayout( new FlowLayout() );

		 contentPane.add(jlbString);
		 final JTextField jtfInput = new JTextField( 10 );
		 contentPane.add( jtfInput );

		 JButton jbnAdd = new JButton("Add");
		 jbnAdd.addActionListener( new ActionListener(){
			 public void actionPerformed( ActionEvent e ){
				 vector.addElement( jtfInput.getText().trim() );
				 jlbStatus.setText("Appended to end: " 

							+ jtfInput.getText().trim() );
				 jtfInput.setText("");
			 }
		 } );
		 contentPane.add(jbnAdd); 

		 JButton jbnRemove = new JButton("Remove");
		 jbnRemove.addActionListener( new ActionListener() {
			 public void actionPerformed( ActionEvent e ){
//				 Returns true if element in vector
				 if ( vector.removeElement( jtfInput.getText().trim() ) )
				    jlbStatus.setText( "Removed: " + jtfInput.getText() );
				 else
				    jlbStatus.setText( jtfInput.getText().trim() 

								+ " not in vector" );
			 }
		 } );
		 contentPane.add( jbnRemove );

		 JButton jbnFirst = new JButton( "First" );
		 jbnFirst.addActionListener( new ActionListener() {
			 public void actionPerformed( ActionEvent e ){
				 try {
					 jlbStatus.setText( "First element: " 

								+ vector.firstElement() );
				 }
				 catch ( NoSuchElementException exception ) {
					 jlbStatus.setText( exception.toString() );
				 }
			 }
		 });
		 contentPane.add( jbnFirst );

		 JButton jbnLast = new JButton( "Last" );
		 jbnLast.addActionListener( new ActionListener() {
			 public void actionPerformed( ActionEvent e ){
				 try {
				    jlbStatus.setText( "Last element: " 

								+ vector.lastElement() );
				 }
				 catch ( NoSuchElementException exception ){
					 jlbStatus.setText( exception.toString() );
				 }
			 }
		 });
		 contentPane.add( jbnLast );

		 JButton jbnEmpty = new JButton( "Is Empty?" );
		 jbnEmpty.addActionListener( new ActionListener() {
			 public void actionPerformed( ActionEvent e ){
				 jlbStatus.setText( vector.isEmpty() ? "Vector is empty" : 
					 			"Vector is not empty" );
			 }
		 });
		 contentPane.add( jbnEmpty );

		 JButton jbnContains = new JButton( "Contains" );
		 jbnContains.addActionListener( new ActionListener() {
			 public void actionPerformed( ActionEvent e ){
				 String searchKey = jtfInput.getText().trim();

				 if ( vector.contains( searchKey ) ){
					 jlbStatus.setText( "Vector contains " 

									+ searchKey );
				 } else{
					 jlbStatus.setText( "Vector does not contain " 

									+ searchKey );
				 }
			 }
		});
		 contentPane.add( jbnContains );

		 JButton jbnFindElement = new JButton( "Find" );
		 jbnFindElement.addActionListener( new ActionListener(){
			 public void actionPerformed( ActionEvent e ){
				 jlbStatus.setText( "Element found at location " 
					 + vector.indexOf(jtfInput.getText().trim()));
			 }
		});
		 contentPane.add( jbnFindElement );

		JButton jbnTrim = new JButton( "Trim" );
		jbnTrim.addActionListener( new ActionListener(){
			 public void actionPerformed( ActionEvent e ){
				 vector.trimToSize();
				 jlbStatus.setText( "Vector trimmed to size" );
			 }
		});
		contentPane.add( jbnTrim );

		 JButton jbnSize = new JButton( "Size/Capacity" );
		 jbnSize.addActionListener( new ActionListener() {
			 public void actionPerformed( ActionEvent e ){
				 jlbStatus.setText( "Size = " + vector.size() 

					+ "; Capacity = " + vector.capacity() );
			 }
		 } );
		 contentPane.add( jbnSize );

		 JButton jbnDisplay = new JButton( "Display" );
		 jbnDisplay.addActionListener( new ActionListener() {
			 public void actionPerformed( ActionEvent e ){
				 Enumeration enum = vector.elements();
				 StringBuffer buf = new StringBuffer();

				 while ( enum.hasMoreElements() )
					 buf.append( enum.nextElement() ).append( " " );

				 JOptionPane.showMessageDialog( null, buf.toString(), 

				"Contents of Vector", JOptionPane.PLAIN_MESSAGE );
			 }
		 } );
		 contentPane.add( jbnDisplay );
		 contentPane.add( jlbStatus );

		 setSize( 300, 200 );
		 setVisible(true);
	 }

	 public static void main( String args[] ) {
		 VectorDemo vectorDemo = new VectorDemo();

		 vectorDemo.addWindowListener( new WindowAdapter(){
			 public void windowClosing( WindowEvent e ){
				 System.exit( 0 );
			 }
		 } );
	 }
 }

     

Output

 

Download VectorExample.java