Call Stack

           Each time a method is invoked,the system creates an activation records that stores parameter and variables for the method and places the activation record in an area of memory known as a call stack.A call stack is also known as an execution stack,runtime,stack or machine stack and iti is often shortened to just -the stack-.When a method calls another method,the caller's activation record is kept intact,and a new activation record is created for the new method called.When a method finishes its work and returns to its caller,its activation record is removed from the call stack.
            A call stack stores the activation records in a last-in,first-out fashion:The activation record for the method that is invoked last is removed first from the stack.

MaxMethod

public class MaxMethod{
public static double max(double num1,double num2){

double result;
if(num1>num2){
result=num1;
}else if(num1==num2){
result=num1;
}else
result=num2;

return result;
}
public static void main(String args[]){
System.out.println("Max value is "+max(13,15));

}

}

SumWithMethod

public class SumWithMethod{

public static int sum(int i1,int j1){

int sum=0;
for(int i=i1; i<j1; i++){
sum+=i;
}
return sum;
}
public static void main(String args[]){
System.out.println("Sum is= "+sum(5,7));
}
}

RepeatAddition(Guess Game)

import java.util.*;

public class RepeatAddition{
public static void main(String args[]){
int i=(int)(Math.random()*100);
int j=(int)(Math.random()*100);

Scanner input=new Scanner(System.in);

System.out.println("What is " + i +"+"+ j +"?");

int answer=input.nextInt();

while(i + j != answer){
System.out.println("Wrong answer try again.What is " + i+ "+" + j + "?");
answer=input.nextInt();
}
System.out.println("Correct answer");


}

}

ToSumSeriesNumber

public class ToSumSeriesNumber{
public static void main(String args[]){
int i=0;
int sum=0;
while(i<5){
sum=sum+i;
i++;
}
System.out.println("Sum of 1 2 3 4 ="+sum);
}


}

IntroductionToLoop(Typing Welcome to Java 100 times)

public class IntroductionToLoop{
public static void main(String args[]){
for(int i=0;i<100;i++){
System.out.println("Welcome to Java");
}

//Other types to write Welcome to Java
System.out.println("After that while loop is working");
int i=0;
while(i<100){
System.out.println("Welcome to Java");
i++;

}
}
}

Algebra(solve quadratic equations)

import java.util.*;

public class Algebra{
public static void main(String args[]){

Scanner input=new Scanner(System.in);
System.out.println("Please write 3 numbers to show ax^2+bx+c equation");

System.out.print("a=");
double a=input.nextDouble();
System.out.print("b=");
double b=input.nextDouble();
System.out.print("c=");
double c=input.nextDouble();

double discriminant=(b*b)-(4*a*c);

double r1=(-b+Math.pow(discriminant,0.5))/(2*a);

double r2=(-b-Math.pow(discriminant,0.5))/(2*a);

double r3=(-b/(2*a));

if(discriminant>0){
System.out.println("Equation has two roots,"+"\nr1="+r1+"\nr2="+r2);
}
if(discriminant==0){
System.out.println("Equation has one root,"+"\nr="+r3);
}
if(discriminant<0){
System.out.println("There is no root");
}
}
}