Write a program to implement stack or any other data structure in Java ASSIGNMENT NO 15

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1 Write a program to implement stack or any other data structure in Java ASSIGNMENT NO 15 Title: Demonstrate implementation of data structure in Java Objectives: To learn implementation of data structure in Java. Problem Statement: Write a program to implement stack or any other data structure in Java. Outcomes: Students will be able to learn and understand implementation of stack in Java. Hardware requirements: Any CPU with Pentium Processor or similar, 256 MB RAM or more, 1 GB Hard Disk or more. Software requirements: 64 bit Linux/Windows Operating System, JDK 1.4 or later Theory: In computer science, a data structure is a particular way of organizing data in a computer so that it can be used efficiently. Data structures can implement one or more particular abstract data types (ADT), which specify the operations that can be performed on a data structure and the computational complexity of those operations. In comparison, a data structure is a concrete implementation of the specification provided by an ADT. Different kinds of data structures are suited to different kinds of applications, and some are highly specialized to specific tasks. The implementation of a data structure usually requires writing a set of procedures that create and manipulate instances of that structure. The efficiency of a data structure cannot be analyzed separately from those operations. Following abstract data types are available: 1. Container 2. List 3. Associative array 4. Multimap 5. Set 6. Bag 7. Multiset 8. Stack

2 9. Queue 10. Double-ended queue 11. Priority queue 12. Tree 13. Graph Stack is a linear data structure which follows a particular order in which the operations are performed. The order may be LIFO (Last In First Out) or FILO (First In Last Out). A stack is a container of objects that are inserted and removed according to the last-in-first-out (LIFO) principle. Objects can be inserted at any time, but only the last (the most-recently inserted) object can be removed. Inserting an item is known as pushing onto the stack. Popping off the stack is synonymous with removing an item. The Stack Abstract Data Type: A stack is an abstract data type (ADT) that supports two main methods: - push(o): Inserts object o onto top of stack o Input: Object; o Output: none pop(): Removes the top object of stack and returns it; if stack is empty an error occurs. o Input: none; o Output: Object The following support methods should also be defined peek(): Get the topmost object of stack o Input : none; o Output : Object; size(): Returns the number of objects in stack o Input: none; o Output: integer isempty(): Return a boolean indicating if stack is empty. o Input: none; o Output: boolean

3 top(): return the top object of the stack, without removing it; if the stack is empty an error occurs. o Input: none; o Output: Object A Stack Interface in Java: While, the stack data structure is a built-in class of Java s java.util package, it is possible, and sometimes preferable to define your own specific one, There are many real life examples of stack. Consider the simple example of plates stacked over one another in canteen. The plate which is at the top is the first one to be removed, i.e. the plate which has been placed at the bottommost position remains in the stack for the longest period of time. So, it can be simply seen to follow LIFO/FILO order. Implementation: There are two ways to implement a stack: Using array Using linked list An Array-Based Stack: Create a stack using an array by specifying a maximum size N for our stack, e.g. N = 1,000. The stack consists of an N-element array S and an integer variable t, the index of the top element in array S.

4 Array indices start at 0, so we initialize t to -1 Pseudo-code Algorithm size(): return t +1 Algorithm isempty(): return (t Algorithm push(o): if size() = N then throw a StackFullException t t + 1 S[t] o Algorithm pop(): if isempty() then throw a StackEmptyException e S[t] S[t] null t t-1 return e Conclusion: In this assignment, we have studied and demonstrated implementation of integer stack and its operations in Java. Roll No. Name Student of Date of Performance Date Assessment of Grade Sign of Student Sign Faculty of Program class StackDS private int top; private int elements[]; private int size; StackDS() top=-1; elements =new int[1]; size=1; StackDS(int n) top=-1; elements=new int[n]; size=n; void push(int num) if(top==(size-1)) System.out.println("Stack Full"); else elements[++top]=num;

5 int pop() if(top<0) System.out.println("Stack Empty"); return -1; else return elements[top--]; int peek() return elements[top]; void print() System.out.println("Elements in stack are"); for(int i=top;i>=0;i--) System.out.print(elements[i]+"\t"); System.out.println(); public class StackDemo public static void main(string args[]) System.out.println("Enter size of Stack"); int size=integer.parseint(system.console().readline()); StackDS stack=new StackDS(size); do System.out.println("\n\n*********MENU*************"); System.out.println("1. Push\n2. Pop\n3. Peek\n4. Display\n5. Exit\nEnter your choice:\n"); int choice=integer.parseint(system.console().readline()); switch(choice) case 1: System.out.println("Enter number to push on stack"); int elm=integer.parseint(system.console().readline()); stack.push(elm); break; case 2: System.out.println("Popped Element is "+stack.pop()); break; case 3:

6 System.out.println("Top Element is "+stack.peek()); break; case 4: stack.print(); break; case 5: System.exit(0); default: System.out.println("Wrong choice"); while(true);

7 OUTPUT:

Chapter 2. Stack & Queues. M hiwa ahmad aziz

Chapter 2. Stack & Queues. M hiwa ahmad aziz . Chapter 2 Stack & Queues www.raparinweb.com M hiwa ahmad aziz 1 Stack A stack structure with a series of data elements that Allows access to only the last item inserted. An item is inserted or removed