Here is a code that implements a class Queue.

public class Queue{

public Queue( )
{
    this( DEFAULT_CAPACITY );
}

public Queue( int capacity )
{
    theArray = new Object[ capacity ];
    makeEmpty( );
}

public boolean isEmpty( )
{
    return currentSize == 0;
}

public boolean isFull( )
{
    return currentSize == theArray.length;
}

public void makeEmpty( )
{
    currentSize = 0;
    front = 0;
    back = -1;
}

public Object getFront( )
{
    if( isEmpty( ) )
        return null;
    return theArray[ front ];
}

public Object dequeue( )
{
    if( isEmpty( ) )
        return null;
    currentSize--;

    Object frontItem = theArray[ front ];
    theArray[ front ] = null;
    front = increment( front );
    return frontItem;
}
public void enqueue( Object x ) throws Overflow
{
    if( isFull( ) )
        throw new Overflow( );
    back = increment( back );
    theArray[ back ] = x;
    currentSize++;
}

private int increment( int x )
{
    if( ++x == theArray.length )
        x = 0;
    return x;
}

private Object [ ] theArray;
private int        currentSize;
private int        front;
private int        back;

static final int DEFAULT_CAPACITY = 10;


public static void main( String [ ] args )
{
    Queue q = new Queue( );

    try
    {
        for( int i = 0; i < 10; i++ )
            q.enqueue( new MyInteger( i ) );
    }
    catch( Overflow e ) { System.out.println( "Unexpected overflow" ); }

    while( !q.isEmpty( ) )
        System.out.println( q.dequeue( ) );
}

}