Hi Friend,

2)ComplexNumber.java:
public class ComplexNumber
{
private int a;
private int b;
public ComplexNumber(){
}

public ComplexNumber(int a, int b){
this.a =a;
this.b=b;
}
public String getComplexValue(){
if(this.b < 0){
return a+""+b+"i";
}
else{
return a+"+"+b+"i";
}
}

public static String addition(ComplexNumber num1, ComplexNumber num2){
int a1= num1.a+num2.a;
int b1= num1.b+num2.b;
if(b1<0){
return a1+""+b1+"i";
} else {
return a1+"+"+b1+"i";
}
}

public static String substraction(ComplexNumber num1, ComplexNumber num2){
int a1= num1.a-num2.a;
int b1= num1.b-num2.b;
if(b1<0){
return a1+""+b1+"i";
} else {
return a1+"+"+b1+"i";
}
}

public static String multiplication(ComplexNumber num1, ComplexNumber num2){
int a1= num1.a*num2.a;
int b1= num1.b*num2.b;
int vi1 = num1.a * num2.b;
int vi2 = num2.a * num1.b;
int vi;
vi=vi1+vi2;
if(vi<0){
return a1-b1+""+vi+"i";
} else {
return a1-b1+"+"+vi+"i";
}
}

public static void main(String args[]){
ComplexNumber com1 = new ComplexNumber(-2,-3);
ComplexNumber com2 = new ComplexNumber(-4,-5);
System.out.println(com1.getComplexValue());
System.out.println(com2.getComplexValue());
System.out.println("Addition of both Complex Numbers are :" +ComplexNumber.addition(com1,com2));
System.out.println("Substraction of both Complex Numbers are :" +ComplexNumber.substraction(com1,com2));
System.out.println("Multiplication of both Complex Numbers are :" +ComplexNumber.multiplication(com1,com2));
}
}

continue..

1) class Stack{
protected int st[];
protected int index;

public Stack(int capacity){
st = new int[capacity];
index = -1;
}
public boolean isEmpty(){
return index == -1;
}
public void push(int i){
if(index+1 < st.length)
st[++index] = i;
}
public int pop(){
if(isEmpty())
return 0;
return st[index--];
}
public int peek(){
if (index == -1)
return 0;
return st[index];
}
}
class StackExample{
public static void main(String[] args){
Stack s = new Stack(10);
System.out.println("Adding values in stack using push() method... ");
for(int i=1;i<=5;i++){
s.push(i);
System.out.println("Add : " + i);
}
System.out.println("Top element on stack: "+s.peek());
System.out.println("Removing single value from stack using pop() method... ");
System.out.println("Remove: " + s.pop());
System.out.println("Removing all values from stack using pop() method... ");
while(!s.isEmpty()){
System.out.println("Remove : " + s.pop());
}

}
}