7 stack and vector

using Java

2015

Data Structure Prepared by: Mahmoud Rafeek Al-farra

in Java

7. Stack and Vector

mfarra.cst.ps www.fb.com/MahmoudRFarra

Contents

Implementation Stack using Linked List

Vector and Stack Class

Introduction

Case Study: Evaluating Expressions

Introductionmfarra.cst.ps www.fb.com/MahmoudRFarra

Vector is a subclass of AbstractList, and Stack is

a subclass of Vector in the Java API.

Several data structures were supported earlier,

among them the Vector and Stack classes.

For an interactive demo on how stacks work, go to www.cs.armstrong.edu/liang/animation/web/Stack.html

http://www.cs.armstrong.edu/liang/animation/web/Stack.html


Vector is the same as ArrayList, except that it

contains synchronized methods for accessing

and modifying the vector.

Synchronized methods can prevent data

corruption when a vector is accessed and

modified by two or more threads concurrently.


For the many applications that do not require synchronization, using ArrayList is more efficient than using Vector.

Vector Classmfarra.cst.ps www.fb.com/MahmoudRFarra

Stack Classmfarra.cst.ps www.fb.com/MahmoudRFarra

The Stack class extends Vector to provide a last-in,

first-out (LIFO) data structure

Implementation of Stack as Linked Listmfarra.cst.ps www.fb.com/MahmoudRFarra

A stack can be viewed as a special type of list whose elements are accessed, inserted, and deleted only from the end (top).

Application: Stack of Employeesmfarra.cst.ps www.fb.com/MahmoudRFarra

EmployeeClass

EmpStackClass

EmpSystem

Class

In this class we will create an object of EmpStack class, and then manipulates the list using all operations.

The class of linked list members and operation, this class simulate the list of any thing, the object of this class will be created and used in the class of EmpSystem.

A self referential class called Employee, contains the attributes and behavior of any Employee.

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The self-referential Classmfarra.cst.ps www.fb.com/MahmoudRFarra

1. class Employee {2. public int salary;3. public String name;4. Employee next;5. public Employee()6. {7. salary = 300;8. name = "no name";9. next = null;10. }11. public Employee(int salary, String name)12. {13. this.salary = salary;14. this.name = name; } }

Self Study: To convert it to generic class, go to page 907 in our text book. [ind, N.W]

The EmpStack Classmfarra.cst.ps www.fb.com/MahmoudRFarra

1. class EmpStack2. {3. Employee Top = null;4. int length =0;5. //the operation of stack will be inserted here 6. }

Push Operationmfarra.cst.ps www.fb.com/MahmoudRFarra

Top

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Top

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1

Top

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POP Operationmfarra.cst.ps www.fb.com/MahmoudRFarra

Top

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7 Top

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Create object of EmpStackmfarra.cst.ps www.fb.com/MahmoudRFarra

1. static void Main(string[] args)2. {3. EmpStack stack1 = new EmpStack();4. }

This objet of list will be manipulated using the operations.

Add new node to stackmfarra.cst.ps www.fb.com/MahmoudRFarra

1. public void Push(Employee NewEmp) {2. Employee newe = NewEmp;3. if (Top == null) {4. Top = newe;5. newe.next = null; }6. else {7. newe.next = Top;8. Top = newe; }9. length++;10. }

Delete a node from stackmfarra.cst.ps www.fb.com/MahmoudRFarra

1. public void Pop()2. {3. if (Top == null)4. // print "Stack is Empty!!"5. else6. {7. Top = Top.next;8. length--; 9. }10. 11. }

Stack using Array Listmfarra.cst.ps www.fb.com/MahmoudRFarra

Since the insertion and deletion operations on a

stack are made only at the end of the stack, it is

more efficient to implement a stack with an array

list than a linked list.

Self Study: Develop our car Project to based on array list.[P. 921] [GW, N.W]

Case Study: Evaluating Expressionsmfarra.cst.ps www.fb.com/MahmoudRFarra

Stacks can be used to evaluate expressions.

How does Google evaluate an expression?


The problem can be solved using two stacks

named:

1. operandStack

2. operatorStack

Operands and operators are pushed into the

stacks before they are processed.


When an operator is processed, it is popped from

operatorStack and applied to the first two

operands from operandStack (the two operands

are popped from operandStack).

The resultant value is pushed back to

operandStack.


The algorithm proceeds in two phases:

1. Phase 1: Scanning the expression

2. Phase 2: Clearing the stack

Self Study: Develop a Project to calculate the expressions.[P. 788] [Indi, N.W]


using Java

2015

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7 stack and vector