Best Java Problems and Solutions

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Most Popular Java Problems and Solutions
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most popular ones that you might want to learn about so that you can start memorizing and
applying them when needed.
List of Java Problems and Solutions
1. Create a Java program displaying Hello World on screen
Solution:
public class HelloWorld
{
public static void main(String[] args)
{
System.out.println("Hello World.");
}
}

2. Create a Java program displaying asterisk pattern.
Solution:
*****
*****
*****
*****
*****
public class JavaExercises
{
{
printAsterisk();
}
static void printAsterisk(){
System.out.println("*****");
}
}
3. Create a Java program declaring 2 integer variables, 1 float variable as
well as 1 string variable, then assign 10, 12.5 as well as “Java
programming” respectively. After that, display the values on screen.
Solution:
{

{
accessVariables();
}
static void accessVariables(){
int x;
float y;
String s;
x = 10;
y = 12.5f;
s = "Java programming";
System.out.println(x);
System.out.println(y);
System.out.println(s);
}
}
4. Create a Java program with the use of the BufferedReader class in
prompting user to input her or his name. The output will be like this:
Hello Dara!
Solution:
import java.io.*;
{
{
printName();
}
static void printName(){
String pname=null;
try{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.print("Enter your name:");
pname=br.readLine();
}catch(IOException e){}

System.out.println("Hello "+pname);
}
}
5. Write an example method printing numbers one to ten.
Solution:
oneToTen()
*** Output ***
1
2
3
4
5
6
7
8
9
10
6. Write an example method printing positive odd numbers that is less
than 20.
Solution:
oddNumbers()
*** Output ***
1
3

5
7
9
11
13
15
17
19
7. Write an example method printing square numbers up to one hundred.
Solution:
squares()
*** Output ***
1
4
9
16
25
36
49
64
81
100
8. Write an example loop in printing out 4 random integers between one
and ten.

Solution:
random4()
*** Output ***
3
5
2
8
9. Write an example method printing out positive even numbers that is less
than n.
Solution:
1: even(20)
2: *** Output ***
3: 2
4: 4
5: 6
6: 8
7: 10
8: 12
9: 14
10: 16
11: 18
10.Write an example method printing out powers of two from 21
up to 2n.
Solution:
powers(8)

: *** Output ***
2
4
8
16
32
64
128
256
11. Create an example program that outputs “ Are we there yet?” Wait for
the input and if it say “yes”, then the outputs program is “good” and
then exit.
Solution:
"Are we there yet?"
No
"Are we there yet?"
Spoons
"Are we there yet?"
Yes
Good!
12. Create an example method using nested loops in producing a pattern.
Solution:
triangle()
*** Output ***

*
**
***
****
*****
13. Create an example method printing out 4x4 table square.
Solution:
tableSquare()
*** Output ***
A 4 x 4 table square
| 1 | 2 | 3 | 4 |
| 1 | 2 | 3 | 4 |
| 2 | 4 | 6 | 8 |
| 3 | 6 | 9 | 12 |
| 4 | 8 | 12 | 16 |
14. Write an example extending your answer to last question producing
method printing out n x n table square.
Solution:
tableSquares(6)
*** Output ***
A 6 x 6 table square
| 1 | 2 | 3 | 4 | 5 | 6 |
| 2 | 4 | 6 | 8 | 10 | 12 |
| 3 | 6 | 9 | 12 | 15 | 18 |

| 4 | 8 | 12 | 16 | 20 | 24 |
| 5 | 10 | 15 | 20 | 25 | 30 |
| 6 | 12 | 18 | 24 | 30 | 36 |
15. Write an example method printing out string array, 1 element for every
line
Solution:
String [] breakfast = {"Sausage", "Eggs", "Beans", "Bacon", "Tomatoes", "Mushrooms"};
printArray(breakfast)
*** Output ***
Sausage
Eggs
Beans
Bacon
Tomatoes
Mushrooms
16. Create an example method returning to the last element of the string
array.
Solution:
String [] breakfast = {"Sausage", "Eggs", "Beans", "Bacon", "Tomatoes", "Mushrooms"}
System.out.println(lastElement(breakfast));
*** Output ***
Mushrooms

17. Create an example method returning to the last, but 1 element of the
string array.
Solution:
System.out.println(lastButOne(breakfast));
*** Output ***
Tomatoes
18. Create an example method reversing elements of the Array.
Solution:
System.out.println(reverse(breakfast));
*** Output ***
: Mushrooms
: Tomatoes
: Bacon
: Beans
: Eggs
: Sausage
: Tails
19. Write a method testing to see if the array is palindromic. For example,
elements are same when it is reversed.
Solution:

String [] palindromic = {"Sausage", "Eggs", "Beans", "Beans", "Eggs", "Sausage"};
System.out.println(isPalindrome(palindromic));
System.out.println(isPalindrome(breakfast));
*** Output ***
True
False
20. Write a method printing out int array with the consecutive duplicated
eliminated.
Solution:
int [] nums = {1,1,3,3,3,2,2,2,1,1,1,1,4,4,4,4};
compress(nums)
*** Output ***
5: 1
: 3
: 2
: 1
: 4
: 1
: 1
21. Pack consecutive duplicated of the char array into the strings.
Solution:

char [] letters = {'a' 'a' 'a' 'a' 'b' 'c' 'c' 'a' 'a' 'd' 'e' 'e' 'e' 'e'};
pack(nums)
*** Output ***
: aaaa, b, cc, aa, d, eeee
22. Create a method returning the number of words in the string.
Solution:
String s = "I never saw a purple cow"
System.out.println(countWords(s));
*** Output ***
6
23. Create a method counting instances of letter “e” in the string.
Solution:
System.out.println(countEs(s));
*** Output ***
3
24. Write a method returning number of the alphanumeric characters in
string.
Solution:
String s = "1984 by George Orwell."

System.out.println(countChars(s));
*** Output ***
18
25. Create a method returning the string, reversed.
Solution:
System.out.println(reverse(s));
*** Output ***
woc elprup a was reven I
26. Create a method testing if the string is palindrome.
Solution:
String sentence = "I never saw a purple cow"
String palindrome = "rotavator"
System.out.println(isPalindrome(sentence));
System.out.println(isPalindrome(palindrome));
*** Output ***
False
True
27.Create improved palindrome that disregard punctuation, case and
spaces as well as recognize sentences like “ A man, a plan, a canal,
Panama!” as palindrome.

Solution:
String p = "Rise to vote, Sir!"
System.out.println(isPalindrome(s));
System.out.println(isPalindrome(p));
*** Output ***
False
True
28. Write a method replacing vowels in the word with the asterisks.
Solution:
star(s)
*** Output ***
* n*v*r s*w * p*rpl* c*w
29. Create method spelling out words. For example, This will become T-H-I-
S.
Solution:
spellOut(s)
*** Output ***
I N-E-V-E-R S-A-W A P-U-R-P-L-E C-O-W

30.In simple substitution cipher, A=1, B=2, C=3 and others. Create a
method encoding sentence with the use of cipher.
Solution:
String s = "Hello World"
encode(s)
*** Output ***
8,5,12,12,15 23,15,18,12,4
31. Create decoder method for the substitution cipher.
Solution:
String s = "9 14,5,22,5,18 19,1,23 1 16,21,18,16,12,5 3,15,23"
decode(s)
*** Output ***
i never saw a purple cow
32. Determine if the given integer number is a prime.
Solution:
public class NNArithmetic {
NNArithmetic()
{
System.out.println(isPrime(7));

}
boolean isPrime(int a)
{
//Special cases
if(a==1) return false;
if(a==2) return true;
boolean prime = true;
int count = 2;
do
{
if (a%count==0)
{
prime = false;
}
count++;
} while(prime == true && count*count <=a);
return prime;
}

{
new NNArithmetic();
}
}
33. Use the Euclid’s Algorithm in determining Greatest Common Divisor of
2 positive integer numbers.
Solution:
NNArithmetic()
{
System.out.println(gcd (1071, 462));
}
int gcd(int a, int b)
{
if(b>a) //Make sure the first number is largest
{
int temp = a;
a = b;

b = temp;
}
while(b>0)
{
int remainder = a%b;
a = b;
b = remainder;
}
return a;
}
{
new NNArithmetic();
}
}
34. Determine whether 2 positive integer numbers are co-prime. 2 numbers
are co-prime if the greatest common divisor equals to 1.
Solution:
NNArithmetic()

{
System.out.println(isCoprime(35,64));
}
{
{
int temp = a;
a = b;
b = temp;
}
while(b>0)
{
a = b;
b = remainder;
}
return a;
}

boolean isCoprime(int a, int b)
{
return (gcd(a,b) ==1) ? true : false;
}
{
new NNArithmetic();
}
}
35. Calculate Euler’s totient function phi(m). For instance, m = 10: r =
1,3,7,9; thus phi(m) = 4. Note the special case: phi(1) = 1.
Solution:
NNArithmetic()
{
System.out.println(phi(10));
}
{
{

int temp = a;
a = b;
b = temp;
}
while(b>0)
{
a = b;
b = remainder;
}
return a;
}
boolean isCoprime(int a, int b)
{
return (gcd(a,b) ==1) ? true : false;
}
int phi(int m)
{
if (m==1) return 1; //Special Case

int phi = 0;
for(int i = 1; i<m; i++)
{
if (isCoprime(m,i)) phi++;
}
return phi;
}
{
new NNArithmetic();
}
}
36. Create a method printing prime factors of given positive integer.
Solution:
NNArithmetic()
{
printPrimeFactors(315);
printPrimeFactors(98);
}
void printPrimeFactors(int n)

{
for(int i = 2; i*i<=n; i++)
{
while(n%i == 0)
{
System.out.print(i + " ");
n = n/i;
}
}
if(n>1) System.out.print(n + "n");
else System.out.println("");
}
{
new NNArithmetic();
}
}
37. With the given integers range by its lower limit and upper limit,
construct a list of the prime numbers within that range.
Solution:
NNArithmetic()

{
printPrimesInRange(10,20);
}
{
//Special cases
int count = 2;
do
{
if (a%count==0)
{
prime = false;
}
count++;
return prime;
}

void printPrimesInRange(int a , int b)
{
for (int i = a; i<=b; i++)
{
if (isPrime(i)) System.out.print(i + " ");
}
System.out.println("");
}
{
new NNArithmetic();
}
}
38. Create predicate in finding 2 prime numbers summing up to given even
number.
Solution:
NNArithmetic()
{
printGoldbachPair(28);
printGoldbachPair(1856);
}

{
//Special cases
int count = 2;
do
{
if (a%count==0)
{
prime = false;
}
count++;
return prime;
}
int [] goldbachPair(int n)
{
int count = 2;
int [] pair = new int[2];

boolean foundPair = false;
while(foundPair == false && count <= n/2)
{
if(isPrime(count) && isPrime(n-count))
{
foundPair = true;
pair [0] = count;
pair [1] = (n-count);
}
count++;
}
return pair;
}
void printGoldbachPair(int n)
{
int [] pair = goldbachPair(n);
System.out.println(pair[0] + " + " + pair [1] + " = " + n);
}
{
new NNArithmetic();

}
}
39. With the given integers by lower limit and upper limit, print list of even
numbers as well as their Goldbach composition. Find out how many
cases there are in range of 2..3000.
Solution:
NNArithmetic()
{
printGoldbachList(9, 20);
printGoldbachList(1,2000,50);
}
{
//Special cases
int count = 2;
do

{
if (a%count==0)
{
prime = false;
}
count++;
return prime;
}
int [] goldbachPair(int n)
{
int count = 2;
int [] pair = new int[2];
boolean foundPair = false;
while(foundPair == false && count <= n/2)
{
if(isPrime(count) && isPrime(n-count))
{
foundPair = true;
pair [0] = count;
pair [1] = (n-count);
}
count++;

}
return pair;
}
void printGoldbachPair(int n)
{
int [] pair = goldbachPair(n);
System.out.println(pair[0] + " + " + pair [1] + " = " + n);
}
void printGoldbachList(int a, int b)
{
if(a%2==1) a++; // make sure start on even number
for (int i = a ; i<=b ; i+=2)
{
printGoldbachPair(i);
}
}
void printGoldbachList(int a, int b, int min)
{
if(a%2==1) a++; // make sure start on even number
for (int i = a ; i<=b ; i+=2)

{
int [] pair = goldbachPair(i);
if(pair[0] > min && pair[1] > min) printGoldbachPair(i);
}
}
{
new NNArithmetic();
}
}
40. Create a method printing out the string array, 1 element for every line.
Solution:
public class NNArrays {
NNArrays()
{
printArray(breakfast);
//Alternative Method
printArrayAlt(breakfast);
}

void printArray(String [] array)
{
for(int i = 0; i<array.length; i++)
{
System.out.println(array[i]);
}
}
//Alternative method using for each loop
void printArrayAlt(String [] array)
{
for(String s: array)
{
System.out.println(s);
}
}
{
new NNArrays();
}
}
41. Write a method returning last element of the string array.

Solution:
NNArrays()
{
System.out.println(lastElement(breakfast));
}
String lastElement(String [] array)
{
return array[array.length-1];
}
{
new NNArrays();
}
}
42. Create a method returning last, but 1 element of the string array.
Solution:

NNArrays()
{
//Added two extra arrays for testing
String [] coin = {"Heads", "Tails"};
String [] lonely = {"solo"};
System.out.println(lastButOne(breakfast));
System.out.println(lastButOneSafer(breakfast));
System.out.println(lastButOneSafer(coin));
System.out.println(lastButOneSafer(lonely));
}
String lastButOne(String [] array)
{
}
// The previous method will throw an
// arrayIndexOutOfBoundsException for arrays of length <2.
// This method will return an empty string if length <2
String lastButOneSafer(String [] array)
{

if (array.length<2)
{
return "";
}
else
{
}
}
{
new NNArrays();
}
}
43. Create a method returning elements of the Array in a reverse order.
Solution:
NNArrays()
{
//Added two extra arrays for testing
String [] coin = {"Heads", "Tails"};

printArray(reverse(breakfast));
printArray(reverse(coin));
printArray(reverse(lonely));
}
void printArray(String [] array)
{
for(int i = 0; i<array.length; i++)
{
}
}
String [] reverse(String [] array)
{
for(int i = 0; i<array.length/2;i++)
{
String temp = array[i];
array[i] = array[array.length-i-1];
array[array.length-i-1] = temp;
}

return array;
}
{
new NNArrays();
}
}
44. Create a method testing to see if the array is a palindromic. For
instance, elements are same when it is being reversed.
Solution:
NNArrays()
{
String [] palindromic = {"Sausage", "Eggs", "Beans",
"Beans", "Eggs", "Sausage"};
System.out.println(isPalindrome(palindromic));
System.out.println(isPalindrome(breakfast));
System.out.println(isPalindrome(lonely));
}

boolean isPalindrome(String [] array)
{
boolean isPal = true;
for (int i = 0; i<array.length/2; i++)
{
if (!array[i].equals(array[array.length -i -1]))
isPal = false;
}
return isPal;
}
// The following method doesn't work.
// Need to compare individual elements
boolean isPalindromeWrong(String [] array)
{
if (array.equals(reverse(array)))
{
return true;
}
else
{

return false;
}
}
String [] reverse(String [] array)
{
for(int i = 0; i<array.length/2;i++)
{
String temp = array[i];
array[i] = array[array.length-i-1];
array[array.length-i-1] = temp;
}
return array;
}
{
new NNArrays();
}
}
45. Create a method printing out int array with the consecutives duplicates
eliminated.
Solution:

NNArrays()
{
int [] nums = {1,1,3,3,3,2,2,2,1,1,1,1,4,4,4,4};
int [] num2 = {1,1};
int [] num1 = {1};
compress(nums);
compress(num2);
compress(num1);
}
void compress(int [] array)
{
System.out.println(array[0]);
for (int i = 1; i<array.length; i++)
{
if (array[i]!=array[i-1])
{
}
}

}
{
new NNArrays();
}
}
46. Create a method printing 2D array of any sizes, then test it with the use
of 3 x 3 tic-tact-toe grid.
Solution:
public class NNStringArray {
NNStringArray()
{
tictactoe();
}
void tictactoe()
{
String [][] grid = new String[3][3];
for(int i = 0; i<grid.length; i++)
{

for (int j = 0; j<grid.length; j++)
{
grid[i][j] = "X";
}
}
printArray(grid);
}
void printArray(String [][] grid)
{
{
for(int j = 0; j<grid.length; j++)
{
System.out.print(" | " + grid[i][j]);
}
System.out.println(" | ");
}
}
public static void main(String[] args) {
// TODO code application logic here
new NNStringArray();

}
}
47. Create a 8 x 8 array representing chess board. You should print out
array with the alternate “X” and “O”.
Solution:
NNStringArray()
{
chess();
}
void printArray(String [][] grid)
{
{
for(int j = 0; j<grid.length; j++)
{
System.out.print(" | " + grid[i][j]);
}
System.out.println(" | ");
}
}

void chess()
{
String [][] grid = new String[8][8];
boolean fill = true;
{
for (int j = 0; j<grid.length; j++)
{
grid[i][j] = fill ? "X" : "O";
fill = !fill;
}
fill = !fill;
}
printArray(grid);
}
}
}
48. Create a method converting digits to words.
Solution:

NNStringArray()
{
System.out.println(digitsToWords("35001922"));
}
String digitsToWords(String s)
{
String words = "";
String [] digits =
{"Oh","One","Two","Three","Four","Five","Six","Seven","Eight","Nine"};
for (int i = 0; i<s.length();i++)
{
int number = Integer.parseInt(s.substring(i,i+1));
words = words + digits[number] + " ";
}
return words;
}

}
}
49. Create a method converting time into words.
Solution:
NNStringArray()
{
System.out.println(timeToWords("2:05"));
}
String timeToWords(String s)
{
String time = "";
String [] input = s.split(":");

String [] times = {"o'clock","one","two","three","four", "five", "six",
"seven","eight","nine","ten","eleven","twelve","thirteen","fourteen",
"quarter","sixteen","seventeen","eighteen","nineteen","twenty",
"twenty one","twenty two","twenty three","twenty four",
"twenty five","twenty six","twenty seven","twenty eight",
"twenty nine","half past"};
int hours = Integer.parseInt(input[0]);
int minutes = Integer.parseInt(input[1]);
//Watch out for e.g. 12:50 = Ten to One
String sayMinutesp = minutes%5 != 0 ? " minutes" : "";
if (hours == 12 && minutes > 30) hours = 1;
if (minutes == 0)
{
time = times[hours] + " o'clock";
}
else if (minutes == 15)
{
time = "Quarter past " + times[hours];
}
else if (minutes == 45)
{

time = "Quarter to " + times[hours];
}
else if (minutes>30)
{
time = times[60-minutes]+ sayMinutesp + " to " + times[hours];
}
else
{
time = times[minutes] + sayMinutesp + " past " + times[hours];
}
return time;
}
}
}
50. Create a program with the use of arrays translating plain text to morse
code.
Solution:
A B C D E F G

.- -… -.-. -.. . ..-. –.
H I J K L M
…. .. .— -.- .-.. —
N O P Q R S T
-. — .–. –.- .-. … –
U V W X Y Z
..- …- .– -..- -.– __..
NNStringArray()
{
System.out.println(morse("I never saw a purple cow"));
}
String morse(String s)
{
s = s.toLowerCase();
String cipherText = "";
String code [] = {".-","-...","-.-.","-..",".","..-.","--.", "....",
"..", ".---","-.-",".-..","--","-.","---",".--.","--.-",".-.",
"...","-","..-","...-",".--","-..-","-.--","--..", "/"};

for (int i = 0; i<s.length(); i++)
{
int number = s.charAt(i) == ' ' ? 26 : s.charAt(i)-97;
cipherText = cipherText + code[number] + " ";
}
return cipherText;
}
}
}
51. Create a program with the use of arrays translating morse back into
plain text.
Solution:
NNStringArray()
{
System.out.println(demorse(".. / -. . ...- . .-. / ... .- .-- / .- / .--. ..- .-. .--. .-.. . / -.-. --- .--"));
}
String demorse(String s)

{
String cipher = "";
String code [] = {".-","-...","-.-.","-..",".","..-.","--.", "....",
"..", ".---","-.-",".-..","--","-.","---",".--.","--.-",".-.",
"...","-","..-","...-",".--","-..-","-.--","--..", "/"};
String [] letters = s.split("s+");
String plainText= "";
for (int i = 0; i<letters.length;i++)
{
String letter = letters[i].trim();
if (letter.equals("/"))
{
plainText = plainText + " ";
}
else
{
String decode = "";
for(int j = 0; j <code.length; j++)
{
if (letter.equals(code[j]))

{
char c = (char)(j+97);
plainText = plainText + Character.toString(c);
}
}
}
}
return plainText;
}
}
}
52. Rewrite morse code program with the use of Hashmap.
Solution:
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

Map <String, String> morse = new HashMap<String, String>();
NNStringArray()
{
morse.put("a" , ".-");
morse.put("b" , "-...");
morse.put("c" , "-.-.");
morse.put("d" , "-..");
morse.put("e" , ".");
morse.put("f" , "..-.");
morse.put("g" , "--.");
morse.put("h" , "....");
morse.put("i" , "..");
morse.put("j" , ".---");
morse.put("k" , "-.-");
morse.put("l" , ".-..");
morse.put("m" , "--");
morse.put("n" , "-.");
morse.put("o" , "---");
morse.put("p" , ".--.");
morse.put("q" , "--.-");
morse.put("r" , ".-.");
morse.put("s" , "...");
morse.put("t" , "-");

morse.put("u" , "..-");
morse.put("v" , "...-");
morse.put("w" , ".--");
morse.put("x" , "-..-");
morse.put("y" , "-.--");
morse.put("z" , "--..");
morse.put(" " , "/");
System.out.println(morseHash("I never saw a purple cow"));
}
String morseHash(String s)
{
String cipherText = "";
for (int i = 0; i<s.length(); i++)
{
cipherText = cipherText + morse.get(s.substring(i,i+1)) + " ";
}
return cipherText;
}

}
}
53. Rewrite demorse code program with the use of Hashmap.
Solution:
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
Map <String, String> morse = new HashMap<String, String>();
NNStringArray()
{
morse.put("a" , ".-");
morse.put("b" , "-...");
morse.put("c" , "-.-.");
morse.put("d" , "-..");
morse.put("e" , ".");
morse.put("f" , "..-.");

morse.put("g" , "--.");
morse.put("h" , "....");
morse.put("i" , "..");
morse.put("j" , ".---");
morse.put("k" , "-.-");
morse.put("l" , ".-..");
morse.put("m" , "--");
morse.put("n" , "-.");
morse.put("o" , "---");
morse.put("p" , ".--.");
morse.put("q" , "--.-");
morse.put("r" , ".-.");
morse.put("s" , "...");
morse.put("t" , "-");
morse.put("u" , "..-");
morse.put("v" , "...-");
morse.put("w" , ".--");
morse.put("x" , "-..-");
morse.put("y" , "-.--");
morse.put("z" , "--..");
morse.put(" " , "/");
System.out.println(demorseHash(".. / -. . ...- . .-. / ... .- .-- / .- / .--. ..- .-. .--. .-.. . / -.-.
--- .--"));

}
String demorseHash(String s)
{
String [] letters = s.split("s+");
String plaintext = "";
for (int i = 0; i<letters.length; i++)
{
for (Entry<String, String> entry : morse.entrySet()) {
if (entry.getValue().equals(letters[i])) {
plaintext = plaintext + entry.getKey();
}
}
}
return plaintext;
}
}

}
54. To write a java program to print fibonacci series upto 100, you need a
code. Give a code of it.
Solution:
import java.util.Scanner;
/**
* Java program to calculate and print Fibonacci number using both recursion
* and Iteration.
* Fibonacci number is sum of previous two Fibonacci numbers fn= fn-1+ fn-2
* first 10 Fibonacci numbers are 1, 1, 2, 3, 5, 8, 13, 21, 34, 55
*
* @author Javin
*/
publicclass FibonacciCalculator {
publicstaticvoid main(String args[]) {
//input to print Fibonacci series upto how many numbers
System.out.println("Enter number upto which Fibonacci series to print: ");
int number = new Scanner(System.in).nextInt();
System.out.println("Fibonacci series upto " + number +" numbers : ");
//printing Fibonacci series upto number

for(int i=1; i<=number; i++){
System.out.print(fibonacci2(i) +" ");
}
}
/*
* Java program for Fibonacci number using recursion.
* This program uses tail recursion to calculate Fibonacci number for a given number
* @return Fibonacci number
*/
publicstaticint fibonacci(int number){
if(number == 1 || number == 2){
return 1;
}
return fibonacci(number-1) + fibonacci(number -2); //tail recursion
}
/*
* Java program to calculate Fibonacci number using loop or Iteration.
* @return Fibonacci number
*/
public static int fibonacci2(int number){
if(number == 1 || number == 2){
return 1;

}
int fibo1=1, fibo2=1, fibonacci=1;
for(int i= 3; i<= number; i++){
//Fibonacci number is sum of previous two Fibonacci number
fibonacci = fibo1 + fibo2;
fibo1 = fibo2;
fibo2 = fibonacci;
}
return fibonacci; //Fibonacci number
}
}
Output:
Enter number upto which Fibonacci series to print:
12
Fibonacci series upto 12 numbers :
1 1 2 3 5 8 13 21 34 55 89 144
55. In java program to print fibonacci series upto 100, show how to create
Fibonacci series.
Solution:
Code:
?
package com.java2novice.algos;

public class MyFibonacci {
public static void main(String a[]){
int febCount = 15;
int[] feb = new int[febCount];
feb[0] = 0;
feb[1] = 1;
for(int i=2; i < febCount; i++){
feb[i] = feb[i-1] + feb[i-2];
}
for(int i=0; i< febCount; i++){
System.out.print(feb[i] + " ");
}
56. Show how to create Fibonacci series Java.
Solution:
public class JavaFibonacciSeriesExample {

//number of elements to generate in a series
int limit = 20;
long[] series = new long[limit];
//create first 2 series elements
series[0] = 0;
series[1] = 1;
//create the Fibonacci series and store it in an array
for(int i=2; i < limit; i++){
series[i] = series[i-1] + series[i-2];
}
//print the Fibonacci series numbers
System.out.println("Fibonacci Series upto " + limit);
for(int i=0; i< limit; i++){
System.out.print(series[i] + " ");
}
}
}
/*

Output of the Fibonacci Series Java Example would be
Fibonacci Series upto 20
0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181
*/
57. Show how to print Fibonacci series between one to one hundred.
Solution:
Print fibonacci series between 1 to 100
like 0 1 1 2 3 5 8 13 21 34 55 89 144
?
publicclassFibonaci {
publicstaticvoidmain(String[] args) {
intn1 = 0, n2 = 1, num;
System.out.print(n1 + " "+
n2 + " ");
for(inti = 0; i < 100; i++) {
num = n2 + n1;
System.out.print(num + " ");
n1 = n2;
n2 = num;
}
}
}

58.In vending machine java program,for example; if you enter 5 for item
and.10 for paid, then why does it say Please insert another $1.4 instead
of 1.40? Even though 1.50 - 1.4 and 1.50 - 1.40 would be the same, how
can you solve the issue?
Solution: use arrays to help solve the issue.
59. Write a program finding Fibonacci series of given number. For
example:
Input – 8
Output - 1 1 2 3 5 8 13 21
Solution:
class Fibonacci{
publicstaticvoid main(String args[]){
int num = Integer.parseInt(args[0]); //taking no. as command line
argument.
System.out.println("*****Fibonacci Series*****");
int f1, f2=0, f3=1;
for(int i=1;i<=num;i++){
System.out.print(" "+f3+" ");
f1 = f2;
f2 = f3;
f3 = f1 + f2;
}
}
}
There you have our list of the most popular Java problems and solutions to learn
about, so refer to this guide when looking for formulas to use in specific Java
problems and contact us when you need Java assignment help!

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