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Amstrong number return in blank result (java)

public class Amstrong {
public static void main(String[] args) {
for (int i = 100; i < 1000; i++) {
String a = String.valueOf(i);
int b = a.charAt(0);
int c = a.charAt(1);
int d = a.charAt(2);
int e = b * b * b + c * c * c + d * d * d;
if (e == i) {
System.out.println(i);
}
}
}
}
//Help me out please, no error occurred but the result returned in the blank

You are not converting the characters to digits correctly.
One of the possible ways to fix it:
int b = a.charAt(0)-'0';
int c = a.charAt(1)-'0';
int d = a.charAt(2)-'0';
Another way:
int b = Character.digit (a.charAt(0),10);
int c = Character.digit (a.charAt(1),10);
int d = Character.digit (a.charAt(2),10);
Either way will give your the output:
153
370
371
407

Another way you can do it is:
import java.util.*;
public class ArmstrongNumber3
{
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter any number");
int n = sc.nextInt();
int b = n;
int sum = 0;
int d = 0;
while (n != 0) {
d = n % 10;
sum += (d * d * d);
n = n / 10;
}
if (sum == b) {
System.out.println("Armstrong");
} else
{
System.out.println("Not Armstrong");
}
}
}

import java.util.Scanner;
public class Amstrong {
public static void main(String args[]) {
Integer num, temp, len = 0, initVal;
double finalVal = 0;
Scanner scn = new Scanner(System.in);
System.out.println("Enter the number");
num = scn.nextInt();
initVal = num;
temp = num;
while (temp != 0) {
temp = temp / 10;
len++;
}
for (int i = 0; i <= len; i++) {
temp = num % 10;
finalVal = finalVal + Math.pow(temp, len);
num = num / 10;
}
if (Double.valueOf(initVal) == finalVal) {
System.out.println("Amstrong");
} else {
System.out.println("Not Amstrong");
}
}
}

JAVA How to return list of elements with amstrong numbers from interval [100; 999]

I am new in java and I have got assigment with armstrong numbers.
I am already created new class ArmstrongNumber.java where I initialized method from this website: http://www.programmingsimplified.com/java/source-code/java-program-armstrong-number
Now in a class where is main method I created another method where I am calling ArmstrongNumber class and now I have to return armstrong number from interval from [100 till 999].
There is where I am stuck now .
public static void armtrongNumbs()
{
ArmstrongNumber returnObj = new ArmstrongNumber(); // here i m calling class.
int start = 100;
int end = 999;
for(int i = start; i<= end; i++)
{
number = i + number;
returnObj.Armstrong(number);
}
//returnObj.Armstrong();
}
How could my loop return only armstrong numbers?
Edit: ArmstrongNumber class
class ArmstrongNumber
{
public void Armstrong(int number)
{
int n, sum = 0, temp, remainder, digits = 0;
Scanner in = new Scanner(System.in);
System.out.println("Input a number to check if it is an Armstrong number");
n = in.nextInt();
temp = n;
// Count number of digits
while (temp != 0) {
digits++;
temp = temp/10;
}
temp = n;
while (temp != 0) {
remainder = temp%10;
sum = sum + power(remainder, digits);
temp = temp/10;
}
if (n == sum)
System.out.println(n + " is an Armstrong number.");
else
System.out.println(n + " is not an Armstrong number.");
}
static int power(int n, int r) {
int c, p = 1;
for (c = 1; c <= r; c++)
p = p*n;
return p;
}
}

Based on your requirement, you need logic of ArmstrongNumber.java and mold it to suit as per your requirements.
You just need to use the following code and can stop worrying about using ArmstrongNumber.java
package hello;
public class Abc {
public static void main(String[] args) {
int n, sum, temp, remainder, digits;
int start = 100;
int end = 999;
for (int i = start; i <= end; i++) {
sum = 0;
digits = 0;
temp = i;
// Count number of digits
while (temp != 0) {
digits++;
temp = temp / 10;
}
temp = i;
while (temp != 0) {
remainder = temp % 10;
sum = sum + power(remainder, digits);
temp = temp / 10;
}
if (i == sum)
System.out.println(i + " is an Armstrong number.");
}
}
static int power(int n, int r) {
int c, p = 1;
for (c = 1; c <= r; c++)
p = p * n;
return p;
}
}
Here you can see, how the sum and digits are initialised to zero for every number and then the rest of logic is same. You can verify that 153, 370, 371, 407 are printed as Armstrong numbers.
Hope this helps

try like
public int[] Armstrong(int start ,int end){
int a[],i=0;
for(int i = start; i<= end; i++)
{
number = i + number;
int n, sum = 0, temp, remainder, digits = 0;
Scanner in = new Scanner(System.in);
System.out.println("Input a number to check if it is an Armstrong number");
n = in.nextInt();
temp = n;
// Count number of digits
while (temp != 0) {
digits++;
temp = temp/10;
}
temp = n;
while (temp != 0) {
remainder = temp%10;
sum = sum + power(remainder, digits);
temp = temp/10;
}
if (n == sum)
a[i++]=n;
else
System.out.println(n + " is not an Armstrong number.");
}
return a;
}
static int power(int n, int r) {
int c, p = 1;
for (c = 1; c <= r; c++)
p = p * n;
return p;
}
}

String index out of range (Repeating Sequence of digits)

I seem to be having a problem with my code which is to look for the repeating sequence of digits. I have converted(?) double to string because I get the error unreachable statement. (which I guess helps to looking for the reason why I get the error I have now?).
Whenever I run it, it goes fine until I finish entering N and D.
It'll say "Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 3"
Here is my code below:
import java.util.*;
public class RepeatingSequence{
public static void main(String[] args){
Scanner in = new Scanner(System.in);
System.out.print("Enter N,D: ");
int numerator = in.nextInt();
int denominator = in.nextInt();
double quotient = numerator / denominator;
String number = "" + quotient;
char n = number.charAt(0);
int j = 1;
int z = 0;
String output = "";
char[] index = number.toCharArray();
for ( int i = 2; number.charAt(j) != number.charAt(i); i++ ){
index[z] = number.charAt(z);
index[j] = number.charAt(j);
index[i] = number.charAt(i);
output = output + index[i];
if ( index[i] != index[z] ){
System.out.print(index[z] + ".(" + index[j] + output + ")");
}
}
}
}

just add i < number.length() to the condition
( int i = 2; i < number.length() && number.charAt(j) != number.charAt(i); i++ )

For your exception, I think you should write safer code - something on the lines of:
int len = number.length();
for ( int i = 2; (i < len) && (j < len) &&
number.charAt(j) != number.charAt(i); i++ ){
...
}
I am not attempting to solve the problem that you are trying to solve but just the problem you are facing. Sorry for that.

I changed your code a little bit try it out and see what you think:
public static void main(String[] args){
Scanner in = new Scanner(System.in);
System.out.print("Enter N,D: ");
double numerator = in.nextDouble();
double denominator = in.nextDouble();
double quotient = numerator / denominator;
String number = "" + quotient;
char n = number.charAt(0);
int j = 1;
int z = 0;
String output = "";
char[] index = number.toCharArray();
int max = -1;
int currentNumber = -1;
int temp = -1;
int tempMax = -1;
System.out.println("" + quotient);
boolean check = true;
for(int i = (number.indexOf(".") + 1); i < index.length; i++)
{
if(max == -1)
{
currentNumber = i;
temp = i;
max = 1;
tempMax = 1;
}
else
{
if(index[i] == index[i-1])
{
tempMax++;
}
else
{
if(tempMax > max)
{
check = false;
max = tempMax;
currentNumber = temp;
}
tempMax = 1;
temp = i;
}
}
}
if(check)
{
max = tempMax;
}
System.out.println(index[currentNumber] + " repeats " + max + " times.");
}
Example of input/output:
Enter N,D: 1
3
0.3333333333333333
3 repeats 16 times.

Armstrong Number java

I've got a problem with some simple code. I haven't seen where is the problem in my code. It returns false when it should return true, since 153 is an Armstrong Number.
Following is my code:
public class Armstrong {
static double nArms, unidad, decena, centena, aux;
Armstrong(){
}
Armstrong(double nArms){
this.nArms = nArms;
}
public boolean esArmstrong(double nArms){
aux = nArms % 100;
centena = nArms / 100;
decena = aux / 10;
unidad = aux % 10;
this.nArms = Math.pow(unidad, 3) + Math.pow(decena, 3) +Math.pow(centena, 3);
if(this.nArms == nArms){
return true;
}else{
return false;
}
}
public static void main(String[] args) {
Armstrong arms = new Armstrong();
System.out.println(arms.esArmstrong(153));
}
}

You are using double when you intend to do integer arithmetic. For example, when you write
centena = nArms / 100;
you are doing floating point division, (and centena is assigned the value 1.53) but you want to perform integer division. Use int, long (or BigInteger) instead.

As others already mentioned never use Double for Integer calculation
Now If I were you I would have optimized my code to this
int check=0;
int n=num; // num is user-input number
while(n>0)//suppose n =153
{
int rem=n%10;
check=check+(int)Math.pow(rem,3);
n=n/10;
}
if(check==num)
System.out.println(num+" is Armstrong");
/*First time while loop runs rem = 3 and n= 15
So check = 0+3*3*3=27
Second time while loop runs rem = 5 and n= 1
So check = 27+5*5*5 = 152
Again n =1 so rem = 1 and check = 152+1*1*1 = 153
This time the thw while fails the exits
ultimately check == num so it is armstrong */

import java.util.Scanner;
public class Armstrong {
public static void main(String args[]) {
System.out.println("Input number of digit to find out Armstrong");
Scanner sc = new Scanner(System.in);
int r = sc.nextInt();
String s[] = new String[r];
System.out.println("Please enter digits");
StringBuilder sb = new StringBuilder(r);
for (int i = 0; i < r; i++) {
String userInput = sc.next();
s[i] = userInput;
sb.append(s[i]);
}
int e = Integer.parseInt(sb.toString()); //this is the Integer value entered to check Armstrong number
int d;
int k[] = new int[r];
for (int j = 0; j < r; j++) {
d = Integer.parseInt(s[j]);
k[j] = d * d * d * d* d* d;
}
int m[] = new int[r + 1];
int n[] = new int[r];
for (int l = 1; l <= r; l++) {
n[l - 1] = m[l - 1] + k[l - 1];
m[l] = n[l - 1];
}
if (e == m[r]) {
System.out.println("Entered number is Armstrong number");
} else {
System.out.println("Entered number is not an Armstrong number");
}
}

public void isArmstrong(String n)
{
char[] s=n.toCharArray();
int sum=0;
for(char num:s)
{
int i=Integer.parseInt(Character.toString(num));
int cube=i*i*i;
sum +=cube;
}
if(sum==Integer.parseInt(n))
{
System.out.println("Its an Armstrong Number");
}
else
{
System.out.println("Its not an Armstrong Number");
}
}

import java.util.*;
public class Main
{
public static void check_armstrong(int n)
{
/*Function to check whether a number is an armstrong number or not
Print true if yes else false */
int sum=0;
int temp=n;
while(n>0){
int remainder=n%10;
sum+=remainder*remainder*remainder;
n=n/10;
}
if(temp==sum){
System.out.println(true);
}else
System.out.println(false);
/* Do not change the code beyond this point*/
}
public static void main(String[]args)
{
Scanner sc=new Scanner(System.in);
int n =sc.nextInt();
check_armstrong(n);
}
}

public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number");
int a, c, d, e = 0, temp = 0;
a = sc.nextInt();
c = a;
int z = a;
while (c > 0) {
c = c / 10;
temp++;
}
System.out.println("//");
int temp2 = temp;
while (temp2 > 0) {
int temp1 = 1;
d = a % 10;
for (int i = 0; i < temp; i++) {
temp1 = temp1 * d;
}
e = e + temp1;
a = a / 10;
temp2--;
}
if (z == e) {
System.out.println("number is armstrong");
} else {
System.out.println("number is not armstrong");
}
}

Why is the output remaining the same?

import java.io.*;
public class TestCaseAbcd {
public static void main(String args[]) throws IOException {
InputStreamReader isr = new InputStreamReader(System.in);
BufferedReader stdin = new BufferedReader(
float x0;
float a, c, mod;
int num, ch = 0;
double[] rNumbers;
double[] rTemp;
System.out.println("Enter the SEED value: ");
System.out.println("x0 ");
x0 = Float.parseFloat(stdin.readLine());
System.out.println("Enter the multiplier's value:");
System.out.println("a: ");
a = Float.parseFloat(stdin.readLine());
System.out.println("Enter the value of increment c and modulus m: ");
System.out.println("c: ");
c = Float.parseFloat(stdin.readLine());
System.out.println("m: ");
mod = Integer.parseInt(stdin.readLine());
System.out.println("How many random nunbers u need? ");
num = Integer.parseInt(stdin.readLine());
rNUmbers = new double[num];
rTemp = new double[rNumbers.length];
rTemp[0] = x0;
for (int i = 0; i < num; i++)
{
if(i + 1 != num)
{
rTemp[i + 1] = (((rTemp[i] * a) + c) % mod);
}
else
{
break;
}
}
for (int i = 0; i < rNumbers.length; i++)
{
if (i + 1 != num)
{
rNumbers[i] = rTemp[i] / mod;
}
else
{
break;
}
}
System.out.println("The PSEUDO random numbers are: ");
for (int i = 0; i < rNumbers.length; i++)
{
System.out.println(rNumbers[i]);
}
double firstNum = rNumbers[0];
System.out.println("1. Select Mutant 1 ");
System.out.println("2. Select Mutant 2 ");
System.out.println("3. Exit ");
}
}
In the above code, the expected output should start from: 0.68.
But, instead it started from:
0.37.
In fact, even after I changed the following code:
rTemp[i+1] = ( ( (rTemp[i]*a) + c ) % mod);
to:
rTemp[i+1] = ( ( (rTemp[i]/a) + c ) % mod);
The output still started from 0.37.
The input values are:
x0 = 37
a = 7
c = 9
m = 100
Please help me in analyzing the code so as that the output shouldn't start with 0.37.
Summary of the problem: the code is producing the same number i.e. 0.37 no matter what the equation stated above in the code is modified to.

You're setting the first value in rTemp to 37, then you start printing from the first value. It only makes sense that the first value printed would be 0.37.
x0 = 37
mod = 100
...
rTemp[0] = x0;
...
rNumbers[i] = rTemp[i] / mod;
...
System.out.println(rNumbers[i]);
To achieve the output you're looking for, change this:
rTemp[0] = x0;
for (int i = 0; i < num; i++)
{
if(i + 1 != num)
{
rTemp[i + 1] = (((rTemp[i] * a) + c) % mod);
}
else
{
break;
}
}
to this:
rTemp[0] = (((x0 * a) + c) % mod);
for (int i = 0; i < num-1; i++)
{
rTemp[i + 1] = (((rTemp[i] * a) + c) % mod);
}
On a side note, if all you really want is an array of psudo-random doubles, it's easier to do something like this:
Random rnd = new Random(seed);
double[] rNumbers = new double[num];
for(int i = 0; i < num; i++)
rNumbers[i] = (double)rnd.nextInt(100) / 100;
For any given seed, you'll get the same array of doubles every time.