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While loop in Java :: keep dividing while contion is not met

I have a basic code:
public class experiment {
public static void main(String[] args) {
System.out.println(experiment(80));
}
public static int experiment (int number) {
while (number > 10) {
number = number / 2;
return number;
} return -1;
}
}
It returns me 40.
So it means is not looping on the variable number.
I would like it to keep looping on number (80, 40, 20, 10), till it return 10.
Is there a way to do it without using the for loop?

Move the return out of the loop:
public static int experiment (int number) {
while (number > 10) {
number = number / 2;
}
return number;
}
If you need the -1 for a special case, you should check it before entering the loop:
public static int experiment (int number) {
if (number < 0) { // or some condition
return -1;
}
while (number > 10) {
number = number / 2;
}
return number;
}
BTW, start using a debugger, you can step through this kind of code and find the problem easily.

What wrong is that you put return number inside the while loop it will end the iteration and return the value of 40. So you have to,
public static int experiment (int number) {
while (number > 10) {
number = number / 2;
}
return number;
}
If you want all the numbers the loop has passed to print;
public static void experiment (int number) {
while (number > 10) {
number = number / 2;
System.out.println(number);
}
}

using recursion:
public class test {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println(test.toTen(80));
}
public static int toTen(int k) {
if (k==10) {
return k;
}
else {
return toTen(k/2);
}
}
}
or simply edit the loop like so
while (k > 10) {
k = k / 2;
}
return k;

Cool Number Counter

For this lab a cool number is any number that when divided by 3,4,5 & 6 will leave a remainder of 1. I have done the static boolean IsCoolNumber and I made a private int b to use as a counter but I have absolutely no idea where I would put for example a b++. Any help would greatly be appreciated.
Thanks in advance!
import static java.lang.System.*;
public class CoolNumbers
{
private int b=0;
public static boolean isCoolNumber( int num )
{
int x;
x = 6;
for(x = 6; x<num; x++)
{
if ((x%3==1) && (x%4==1) && (x%5 ==1) && (x%6 == 1))
return true;
}
return false;
}
public static int countCoolNumbers( int stop )
{
//add counter
}
public static void main( String[] args )
{
System.out.println( CoolNumbers.countCoolNumbers(250) + " cool numbers between 6 - " + 250);
//add more test cases
}
}

In isCoolNumber you don't need a loop, a single statement will do.
public static boolean isCoolNumber(int x) {
return (x % 3 == 1) && (x % 4 == 1) && (x % 5 == 1) && (x % 6 == 1);
}
To count the "cool numbers" add a simple loop in the currently empty countCoolNumbers( int stop ) method.
for (int i = start; i < stop; i++) {
if (isCoolNumber(i)) {
count++;
}
}

Write your method countCoolNumbersas below and try it...
public static int countCoolNumbers( int stop ){
boolean check=isCoolNumber(stop);
int num=0;
if(check==true){
num=stop;
}
num=0;
return num;
`}
public static void main( String[] args ) {
System.out.println( CoolNumbers.countCoolNumbers(250) + " cool numbers between 6 - " + 250);
//add more test cases
}
Then output will be:
0 cool numbers between 6 - 250

Prime Factorization Program in Java Using Loops

I have to write a program that takes a number from the user and then displays the prime factors of the number. This is the program I have so far:
public static void main(String[] args) {
int a = getInt("Give a number: ");
int i = 0;
System.out.println("Your prime factors are: " + primeFactorization(a, i));
}
public static int getInt(String prompt) {
int input;
System.out.print(prompt);
input = console.nextInt();
return input;
}
public static int primeFactorization(int a, int i) {
for (i = 2; i <= a ; i++) {
while (a % i == 0) {
a /= i;
}
}
return i;
}
}
I can't figure out how to get it to print out the list of numbers. Any help is appreciated.

You should return a List<Integer> not a single int, and there is no point in i being an argument. A correct method is
public static List<Integer> primeFactorization(int a) {
List<Integer> list = new ArrayList<Integer>();
for (int i = 2; i <= a ; i++) {
while (a % i == 0) {
list.add(i);
a /= i;
}
}
return list;
}

While #Paul Boddington's answer is better in most cases (i.e. if you are using the values afterwards), for a simple program like yours, you could add all of the factors to a string and return the string. For example:
public static String primeFactorization(int a) {
String factors = "";
for (int i = 2; i <= a ; i++) {
while (a % i == 0) {
factors += i + " ";
a /= i;
}
}
return factors;
}

How to print a variable as defined in a method?

public class Program {
public static void main(String[] args) {
int lastFibo = 1; // ADDED TO check if last fib calculated is over 4000000
for (int i = 3; lastFibo <= 4000000; i = i + (i - 1)) {
lastFibo = fibo(i);
}
}
public static int fibo(int i) {
int total = 0;
if (i % 2 == 0) {
total += i;
return total;
}
return total;
}
}
The purpose of this code is to print the sum of even numbers in the fibonacci sequence who's values are less than 4 million. Using recursion the code returns a stack overflow error so it was recommended to iterate through the numbers. The difficulty encountered was knowing how to print the "total" variable. Scope articles are very basic and creating a static int total = 0 would return 0.

First, as pointed out by some comments: your for loop will not iterate the Fibonacci sequence. Second, the variable total exists only in the scope of your fibo method. So every time the method is called, total starts with the value 0.
Use the correct Fibonacci algorithm and add the return value of the fibo method up to calculate the sum:
public class Program {
public static void main(String[] args) {
int total = 0;
int previousValue = 0;
int currentValue = 1;
while (currentValue < 4_000_000) {
int nextPreviousValue = currentValue;
currentValue += previousValue;
previousValue = nextPreviousValue;
total += fibo(currentValue);
}
System.out.println(total);
}
public static int fibo(int i) {
if (i % 2 == 0) {
return i;
}
return 0;
}
}
4_000_000 is an integer literal you can use since Java 7 for the number 4000000. The purpose of the underscores is to make it better readable for humans. Programmatically there is no difference to using 4000000. For details see Primitive Data Types in The Java Tutorials.

Note: This first part of the question was related to a misunderstanding. I supposed that it was necessary to calculated up to fib(4000000).
You must use BigInteger otherwise you can't handle so big numbers. It is a number with many thousands of digits!
fib(4000000) results in a number with over 835k digits. It is not possible to handle it with int or long.
The class BigInteger (or the equivalent BigDecimal for decimal values) borns to handle such kind of problems.
Note: this is the answer to the question
Now that the question is more clear it is possible to give the correct answer.
public void printEvenFib() {
int i = 1;
int lastFib = 1;
int sum = 0;
while (lastFib <= 4000000) {
if (lastFib % 2 == 0) {
sum += lastFib;
}
i++;
lastFib = fib(i);
}
System.out.println(sum);
}
// Without recursion
public int fib(int n) {
if (n <= 2) {
return 1;
}
int fibo1 = 1;
int fibo2 = 1;
int fibo = 0;
for (int i = 3; i <= n; i++) {
fibo = fibo1 + fibo2;
fibo2 = fibo1;
fibo1 = fibo;
}
return fibo;
}

class Program2{
public static void main(String args[]){
int n1=0,n2=1,n3,total=0,i;
for(i=1;n3<4000000;++i){
n3=n1+n2;
if(n3%2==0)
total+=n3;
n1=n2;
n2=n3;
}
System.out.println("total is "+total);
}
}

Cannot find symbol compile error in for loop

I'm having a problem with my code here. I'm trying to find all multiples of 3 and 5 up to one thousand and add them all up, and at the end when I try to output the sum, java gives me a 'cannot find symbol' error. Can anybody figure out what's wrong here?
public class Problem1
{
public static void main(String []args)
{
//int sum1;
//int sum2;
int finalSum;
for(int i = 0; i < 1000; i++)
{
if(i % 3 == 0)
{
int sum;
sum += i;
}
else if(i % 5 == 0)
{
int sum;
sum += i;
}
}
System.out.println(sum);
}
}

Java has block scoping, which means that the sum declared in between {}s (braces) is not visible outside. Declare sum once, outside of the for loop.
public class Problem1
{
public static void main(String []args)
{
int sum = 0;
for(int i = 0; i < 1000; i++)
{
if(i % 3 == 0)
{
sum += i;
}
else if(i % 5 == 0)
{
sum += i;
}
}
System.out.println(sum);
}
}

you can not declare sum in loop.Then it is local to that method.

It's because you're "creating" sum inside the if statements which limits their scope - they're created within the if blocks and destroyed at the next closing brace.
Get rid of those two int sum; lines inside the if blocks and put it at the top of the function (where the rather useless finalSum is). Or just use finalSum everywhere.
You can also combine the if conditions for shorter code:
public class Problem1
{
public static void main(String []args)
{
int finalSum = 0;
for(int i = 0; i < 1000; i++)
if((i % 3 == 0) || (i % 5 == 0))
finalSum += i;
System.out.println(finalSum);
}
}

you have defined the variable sum inside the the if/else which limits the scope of the variable.System.out.print() statement is outside the scope of sum hence you are getting the error.
public class Problem1
{
public static void main(String []args)
{
int sum=0;
for(int i = 0; i < 1000; i++)
{
if(i % 3 == 0)
{
sum += i;
}
else if(i % 5 == 0)
{
sum += i;
}
}
System.out.println(sum);
}
}