25540842 stack data structures in java(1)

7/27/2019 25540842 Stack Data Structures in Java(1)

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Project

Array-based Stack Implementation in Java

Stack

Presented by

Ahmad Abbur Rehman

Khayam Ahmed



// CONSTRUCTION: with no initializer //

// ******************PUBLIC OPERATIONS*********************

// void push( x ) --> Insert x

// void pop( ) --> Remove most recently inserted item// Object top( ) --> Return most recently inserted item

// Object topAndPop( ) --

> Return and remove most recent item

// boolean isEmpty( ) --> Return true if empty; else false

// void makeEmpty( ) --> Remove all items// ******************ERRORS********************************

// top, pop, or topAndPop on empty stack

Building ArrayStack class



/**

* Array-based implementation of the stack.

*/

public class ArrayStack implements Stack {/**

* Construct the stack.

*/

public ArrayStack( ) {theArray = new Object[ DEFAULT_CAPACITY ];

topOfStack = -1;

}



/**

* Test if the stack is logically empty.

* @return true if empty, false otherwise.

*/ public boolean isEmpty( ) {

return topOfStack == -1;

}



/**

* Make the stack logically empty.

*/

public void makeEmpty( ) {topOfStack = -1;

}



/**

* Get the most recently inserted item in the stack.

* Does not alter the stack.

* @return the most recently inserted item in the stack.* @throws UnderflowException if the stack is empty.

*/

public Object top( ) {

if ( isEmpty( ) )

throw new UnderflowException( "ArrayStack top" ); return theArray[ topOfStack ];

}



/**

* Remove the most recently inserted item from the stack.

* @throws UnderflowException if the stack is empty.

*/ public void pop( ) {

if ( isEmpty( ) )

throw new UnderflowException( "ArrayStack pop" );

topOfStack--;

}



/**

* Return and remove the most recently inserted item

* from the stack.

* @return the most recently inserted item in the stack.* @throws Underflow if the stack is empty.

*/

public Object topAndPop( ) {

if ( isEmpty( ) )

throw new UnderflowException( "ArrayStack topAndPop" );

return theArray[ topOfStack-- ];

}



/**

* Insert a new item into the stack.

* @param x the item to insert.

*/ public void push( Object x ) {

if ( topOfStack + 1 == theArray.length )

doubleArray( );

theArray[ ++topOfStack ] = x;

}



/**

* Internal method to extend theArray.

*/

private void doubleArray( ) {Object [ ] newArray;

newArray = new Object[ theArray.length * 2 ];

for ( int i = 0; i < theArray.length; i++ )

newArray[ i ] = theArray[ i ];theArray = newArray;

}

private Object [ ] theArray; private int topOfStack;

private static final int DEFAULT_CAPACITY = 10;

}



/**

* Exception class for access in empty containers

* such as stacks, queues, and priority queues.

* @author Mark Allen Weiss*/

public class UnderflowException extends RuntimeException

{

/**

* Construct this exception object.* @param message the error message.

*/

public UnderflowException( String message ) {

super ( message );}

}



//// ******************PUBLIC OPERATIONS*********************

// void push( x ) --> Insert x

// void pop( ) --> Remove most recently inserted item

// Object top( ) --> Return most recently inserted item// Object topAndPop( ) --

> Return and remove most recent item

// boolean isEmpty( ) --> Return true if empty; else false

// void makeEmpty( ) --> Remove all items

// ******************ERRORS********************************

// top, pop, or topAndPop on empty stack

Creating Stack Interface



/**

* Protocol for stacks.

*/

public interface Stack {/**

* Insert a new item into the stack.

* @param x the item to insert.

*/

void push( Object x );

/**

* Remove the most recently inserted item from the stack

.* @exception UnderflowException if the stack is empty.

*/

void pop( );



Thank You

25540842 stack data structures in java(1)

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