Java Dynamic Stack Implementation
package com.java2novice.ds.stack;
public class MyDynamicStack
{
private
int stackSize;
private int[] stackArr;
private int top;
public MyDynamicStack(int size)
{
this.stackSize
= size;
this.stackArr
= new int[stackSize];
this.top
= -1;
}
public void push(int
entry)
{
if(this.isStackFull())
{
System.out.println(("Stack
is full. Increasing the capacity."));
this.increaseStackCapacity();
}
System.out.println("Adding:
"+entry);
this.stackArr[++top]
= entry;
}
public int pop() throws
Exception
{
if(this.isStackEmpty())
{
throw
new Exception("Stack is empty. Can not remove element.");
}
int
entry = this.stackArr[top--];
System.out.println("Removed
entry: "+entry);
return
entry;
}
public long peek()
{
return
stackArr[top];
}
private void increaseStackCapacity()
{
int[]
newStack = new int[this.stackSize*2];
for(int
i=0;i
{
newStack[i]
= this.stackArr[i];
}
this.stackArr
= newStack;
this.stackSize
= this.stackSize*2;
}
public boolean
isStackEmpty()
{
return
(top == -1);
}
public boolean
isStackFull()
{
return
(top == stackSize - 1);
}
public
static void main(String[] args)
{
MyDynamicStack
stack = new MyDynamicStack(2);
for(int
i=1;i<10 i="" span="">
{
stack.push(i);
}
for(int
i=1;i<4 i="" span="">
{
try
{
stack.pop();
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
}
Stack implementation using generics bound type
package com.java2novice.ds.stack;
public class MyGenericsStack
{
private int stackSize;
private T[] stackArr;
private int top;
SuppressWarnings("unchecked")
public MyGenericsStack(int size)
{
this.stackSize
= size;
this.stackArr
= (T[]) new Object[stackSize];
this.top
= -1;
}
public void push(T entry)
{
if(this.isStackFull())
{
System.out.println(("Stack
is full. Increasing the capacity."));
this.increaseStackCapacity();
}
System.out.println("Adding:
"+entry);
this.stackArr[++top]
= entry;
}
public T
pop() throws Exception
{
if(this.isStackEmpty())
{
throw
new Exception("Stack is empty. Can not remove element.");
}
T
entry = this.stackArr[top--];
System.out.println("Removed
entry: "+entry);
return
entry;
public
T peek()
{
return
stackArr[top];
}
private
void increaseStackCapacity()
{
SuppressWarnings("unchecked")
T[]
newStack = (T[]) new Object[this.stackSize*2];
for(int
i=0;i
{
newStack[i]
= this.stackArr[i];
}
this.stackArr
= newStack;
this.stackSize
= this.stackSize*2;
}
public boolean
isStackEmpty()
{
return
(top == -1);
}
public boolean
isStackFull()
{
return
(top == stackSize - 1);
}
public static void main(String
a[])
{
MyGenericsStack
stringStack = new MyGenericsStack(2);
stringStack.push("java2novice");
MyGenericsStack
integerStack = new MyGenericsStack(2);
integerStack.push(23);
}
}
Reverse a word or string using Stack data structure
package com.java2novice.ds.stack;
public class MyWordReverse
{
public String reverseWord(String word)
{
StringBuilder
sb = new StringBuilder();
int
size = word.length();
StackImpl
stack = new StackImpl(size);
for(int
i=0;i
{
stack.push(word.charAt(i));
}
while(!stack.isStackEmpty())
{
sb.append(stack.pop());
}
return
sb.toString();
}
public static void
main(String a[])
{
MyWordReverse
mwr = new MyWordReverse();
System.out.println("Java2Novice
== "+mwr.reverseWord("Java2Novice"));
System.out.println("Java
== "+mwr.reverseWord("Java"));
System.out.println("program
== "+mwr.reverseWord("program"));
}
}
class StackImpl
{
private
int stackSize;
private char[] stackArr;
private int top;
public StackImpl(int size)
{
this.stackSize
= size;
this.stackArr
= new char[stackSize];
this.top
= -1;
}
public void push(char entry)
{
this.stackArr[++top]
= entry;
}
public char
pop()
{
char
entry = this.stackArr[top--];
return
entry;
}
public char peek()
{
return
stackArr[top];
}
public
boolean isStackEmpty()
{
return
(top == -1);
}
public boolean
isStackFull()
{
return
(top == stackSize - 1);
}
}
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