Develop Reference

Accept two integers separated by a delimiter and print their sum

import java.util.Scanner;
public class Hello {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int A = sc.nextInt().split(":");
int B = sc.nextInt();
System.out.println(A + B);
}
}
If I'm given an input like 1:2 then the output should be 3. Likewise 54:6 then 60.
But I'm getting an error. What should I do to achieve that output?

You cannot call split on an integer, it is meant for splitting a String. Try this:
public class Hello {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String[] numbers = sc.next().split(":");
int A = Integer.parseInt(numbers[0]);
int B = Integer.parseInt(numbers[1]);
System.out.println(A + B);
}
}
Of course some validation would be nice (check if the String contains a colon, if the parts are numeric, etc.), but this should point you in the right direction.

At first, read a whole input line into a String variable. Then just split it into two values and cast them to integer.
Code example:
Scanner sc = new Scanner(System.in);
String inputString = sc.nextLine();
String[] splittedValues = inputString.split(":");
int
A = Integer.parseInt(splittedValues[0]),
B = Integer.parseInt(splittedValues[1]);
System.out.println(A + B);

you will need to take input as string and then split your input by : and convert the string to integer and add them.
see example below
public class Hello {
public static void main(String[] args) {
String input;
Scanner sc = new Scanner(System.in);
input = sc.next();
String[] parts = input.split(":");
if(parts.length > 0) {
int sum = Integer.parseInt(parts[0])+Integer.parseInt(parts[1]);
System.out.println(sum);
} else{
System.out.println("Enter number in format example 12:2");
}
}
}```

You can try this:
import java.util.Scanner;
public class Hello {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int A = sc.nextInt();
sc.next().charAt(0);
int B = sc.nextInt();
System.out.println(A + B);
}
}

I think Splitting of two integers is not possible in java(it is possible in python by using the input.split() function) ,for that reason it is better take input as string and split input by using colon(:) operator and convert those input string to an integer and add the both to print the result.
java code:
import java.util.Scanner;
Public class TwoIntegers
{
public static void main(String args[])
{
Scanner s=new Scanner(System.in());
String[] two_numbers = s.next().split(":");
int fir_num = Int.parseInt(two_numbers[0]);
int sec_num = Int.parseInt(two_numbers[1]);
int sum=fir_num+sec_num;
System.out.println("The sum of two numbers is:"+sum);
}
}

Reading space separated numbers from a file

I'm on my winter break and trying to get my Java skills back up to snuff so I am working on some random projects I've found on codeeval. I'm having trouble opening a file in java doing the fizzbuzz program. I have the actual fizzbuzz logic part down and working just fine, but opening the file is proving problematic.
So presumably, a file is going to be opened as an argument to the main method; said file will contain at least 1 line; each line contains 3 numbers separated by a space.
public static void main(String[] args) throws IOException {
int a, b, c;
String file_path = args[0];
// how to open and read the file into a,b,c here?
buzzTheFizz(a, b, c);
}

You can use the Scanner like so;
Scanner sc = new Scanner(new File(args[0]));
a = sc.nextInt();
b = sc.nextInt();
c = sc.nextInt();
By default scanner uses whitespace and newline as seperators, just what you want.

try {
Scanner scanner = new Scanner(new File(file_path));
while( scanner.hasNextInt() ){
int a = scanner.nextInt();
int b = scanner.nextInt();
int c = scanner.nextInt();
buzzTheFizz( a, b, c);
}
} catch( IOException ioe ){
// error message
}

Using a loop it reads the whole file, have fun:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
int a = 0;
int b = 0;
int c = 0;
String file_path = args[0];
Scanner sc = null;
try {
sc = new Scanner(new File(file_path));
while (sc.hasNext()) {
a = sc.nextInt();
b = sc.nextInt();
c = sc.nextInt();
System.out.println("a: " + a + ", b: " + b + ", c: " + c);
}
} catch (FileNotFoundException e) {
System.err.println(e);
}
}
}

How to read input from user with unknown length?

I want to enter a string of numbers, delimited by ",". I don't know how long it will be. The input will be passed to the program and will end with the letter "x".
JAVA!
import java.util.Scanner;
public class fromUserSum {
/// input : 1,2,4x from user
/// output : 7
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int num;
int sumTotal=0;
while(scan.nextByte() != 'x') {
num = scan.nextInt();
sumTotal += num;
}
System.out.println(sumTotal);
scan.close();
}
}
PLEASE help! :)
//////////////
public class fromUserSum {
/// input : 1,2,4x from user
/// output : 7
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
String userInput;
do {
System.out.println("Please enter a list of numbers in following format: 1,2,3,4x");
userInput = scan.next();
} while (!userInput.matches("(?:\\d+(?:,\\d+)*)x") || !userInput.matches("\\d+( \\d+)*x"));
scan.close();
String[] numberStrings;
if (userInput.contains(",")) {
numberStrings = userInput.replace("x", "").split(","); // 4x is now 4 and split by ','
} else {
numberStrings = userInput.replace("x", "").split(" ");
}
int sum = 0;
for (String i : numberStrings) {
sum += Integer.valueOf(i);
}
System.out.println("The sum of all numbers in the list is: " + sum);
}
}

Try this
public static void main(String[] args) {
int result = 0;
Scanner sc = new Scanner(System.in);
System.out.println("Enter the value");
String string = sc.nextLine();
string = string.replace("x", "");
String[] strArray = string.split(",");
for (String str : strArray) {
result += Integer.valueOf(str);
}
System.out.println("Result is " + result);
}
Input is 1,2,3,4x
Output is Result is 10

import java.io.Console;
import java.util.Scanner;
class MainClass{
public static void main(String args[]) {
int sum=0;
Console c=System.console();
Scanner scan = new Scanner(c.readLine());
scan.useDelimiter("[,x]");
while(scan.hasNextInt())
sum+=scan.nextInt();
scan.close();
System.out.print(sum);
}
}

This does the job as well. Additionally it tells the user what input is expected and if the entered list does not match the format.
public static void main(final String[] args) {
final Scanner userInputScanner = new Scanner(System.in);
String userInput;
do {
System.out.println("Please enter a list of numbers in following format: 1,2,3,4x or 1 2 3 4x");
userInput = userInputScanner.nextLine();
} while (!(userInput.matches("\\d+(,\\d+)*x") || userInput.matches("\\d+( \\d+)*x")));
userInputScanner.close();
final String[] numberStrings = userInput.replace("x", "").split("[, ]");
int sum = 0;
for (final String numberString : numberStrings) {
sum += Integer.valueOf(numberString);
}
System.out.println("The sum of all numbers in the list is: " + sum);
}

Add Problems In java

I want to take input of two variable as integer and than do addition with the two variables.
The ans will stored in another variable. The program will repeat after every addition end and will ask for user input of varibles and will do addition again.
My qus is taht how can i add all aditions ans again:
Exm:
Input a= 5
Input b=5
ans=10
Agin program will ask for
Input a= 6
Input b= 6
ans=12
now how can i take all " ans " value with program and do additions of all "ans"
Final Ans=10+12=22
code:
import java.io.*;
import java.util.Scanner;
public class math{
public void add()
{
Scanner keyboard = new Scanner(System.in);
int a;
int b;
System.out.print("\nEnter a : ");
a = keyboard.nextInt();
System.out.print("Enter b : ");
b = keyboard.nextInt();
int c=a+b;
System.out.println("\nans is :"+c);
math ob_m=new math();
ob_m.add();
}
public static void main(String args[])
{
math ob_main=new math();
ob_main.add();
}
}
The code just do addition one after another but i want that it will do one more task that ....
It all add all aditions reasuts also. how can i do it?

import java.io.*;
import java.util.Scanner;
public class Test {
int a;
int b;
int sum = 0;
public void add() {
Scanner keyboard = new Scanner(System.in);
System.out.print("\nEnter a : ");
a = keyboard.nextInt();
System.out.print("Enter b : ");
b = keyboard.nextInt();
sum = sum + (a + b);
System.out.println("\nans is :" + (a + b));
}
public static void main(String args[]) {
Test ob_main = new Test();
while (true) {
ob_main.add();
}
}
}

Just keep adding the intermediate sums to another variable, so at the end you get the final total.
Another alternative (though not preferable when simple solution is available) is to put these sums in a list and at the end iterate through the list and calculate the final total.
Also, do not use ob_m.add(); - just call add();

Store every answer in an additional variable. Then when you're done, sum all the answer variables

You can use a loop for repeating your action, and store each addition in a total sum?

Change
public void add() {
Scanner keyboard = new Scanner(System.in);
int a;
int b;
int total = 0;
for(int i = 0; i < 2; i++) {
System.out.print("\nEnter a : ");
a = keyboard.nextInt();
System.out.print("Enter b : ");
b = keyboard.nextInt();
int c = a+b;
total += c;
}
System.out.println("\nans is :"+total);
}

Have a total variable which you just keep adding c to.
I also changed your unneeded recursion into a while-loop.
public class math
{
public static void main(String args[])
{
int total = 0;
Scanner keyboard = new Scanner(System.in);
while (true)
{
System.out.print("\nEnter a (-999 to quit): ");
int a = keyboard.nextInt();
// terminating condition, modify appropriately
if (a == -999)
break; // break out of the while-loop
System.out.print("Enter b: ");
int b = keyboard.nextInt();
int c = a + b;
total += c;
System.out.println("\nans is: " + c);
}
System.out.println("total is: " + total);
}
}

have a field GrandSUM,
GrandSum = 0;
and after every addition, add ans to it.
GrandSum += ans;
at the end , GrandSum will have result you want.
Edit:
import java.io.*;
import java.util.Scanner;
public class math{
int GrandSum = 0;//added
public void add()
{
Scanner keyboard = new Scanner(System.in);
int a;
int b;
System.out.print("\nEnter a : ");
a = keyboard.nextInt();
System.out.print("Enter b : ");
b = keyboard.nextInt();
int c=a+b;
GrandSum += c;//added
System.out.println("\nans is :"+c);
}
public static void main(String args[])
{
math ob_main=new math();
ob_main.add();
//.....repeat as many times you want
ob_main.add();
System.out.println("grandsum: " + ob_main.GrandSum);
}
}

package farzi;
import java.util.ArrayList;
import java.util.Scanner;
public class dummy {
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
ArrayList<Integer> list1 = new ArrayList<Integer>();
ArrayList<Integer> list2 = new ArrayList<Integer>();
ArrayList<Integer> sum = new ArrayList<Integer>();
String choice = "";
do{
System.out.println("enter the first number");
int a = keyboard.nextInt();
System.out.println("enter the second number");
int b = keyboard.nextInt();
int tempSum = a+b;
list1.add(a);
list2.add(b);
sum.add(tempSum);
System.out.println("Do you want to continue : type yes or no");
choice = keyboard.next();
}while(choice.toLowerCase().charAt(0)=='y');
System.out.println("here are the inputs with theri sum");
System.out.println("num1\t num2\t sum");
for(int i=0;i<list1.size();i++)
{
System.out.println(list1.get(i)+"\t"+list2.get(i)+"\t"+sum.get(i));
}
}
}

how to take user input in Array using java?

how to take user input in Array using Java?
i.e we are not initializing it by ourself in our program but the user is going to give its value..
please guide!!

Here's a simple code that reads strings from stdin, adds them into List<String>, and then uses toArray to convert it to String[] (if you really need to work with arrays).
import java.util.*;
public class UserInput {
public static void main(String[] args) {
List<String> list = new ArrayList<String>();
Scanner stdin = new Scanner(System.in);
do {
System.out.println("Current list is " + list);
System.out.println("Add more? (y/n)");
if (stdin.next().startsWith("y")) {
System.out.println("Enter : ");
list.add(stdin.next());
} else {
break;
}
} while (true);
stdin.close();
System.out.println("List is " + list);
String[] arr = list.toArray(new String[0]);
System.out.println("Array is " + Arrays.toString(arr));
}
}
See also:
Why is it preferred to use Lists instead of Arrays in Java?
Fill a array with List data

package userinput;
import java.util.Scanner;
public class USERINPUT {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
//allow user input;
System.out.println("How many numbers do you want to enter?");
int num = input.nextInt();
int array[] = new int[num];
System.out.println("Enter the " + num + " numbers now.");
for (int i = 0 ; i < array.length; i++ ) {
array[i] = input.nextInt();
}
//you notice that now the elements have been stored in the array .. array[]
System.out.println("These are the numbers you have entered.");
printArray(array);
input.close();
}
//this method prints the elements in an array......
//if this case is true, then that's enough to prove to you that the user input has //been stored in an array!!!!!!!
public static void printArray(int arr[]){
int n = arr.length;
for (int i = 0; i < n; i++) {
System.out.print(arr[i] + " ");
}
}
}

import java.util.Scanner;
class bigest {
public static void main (String[] args) {
Scanner input = new Scanner(System.in);
System.out.println ("how many number you want to put in the pot?");
int num = input.nextInt();
int numbers[] = new int[num];
for (int i = 0; i < num; i++) {
System.out.println ("number" + i + ":");
numbers[i] = input.nextInt();
}
for (int temp : numbers){
System.out.print (temp + "\t");
}
input.close();
}
}

You can do the following:
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
int arr[];
Scanner scan = new Scanner(System.in);
// If you want to take 5 numbers for user and store it in an int array
for(int i=0; i<5; i++) {
System.out.print("Enter number " + (i+1) + ": ");
arr[i] = scan.nextInt(); // Taking user input
}
// For printing those numbers
for(int i=0; i<5; i++)
System.out.println("Number " + (i+1) + ": " + arr[i]);
}
}

It vastly depends on how you intend to take this input, i.e. how your program is intending to interact with the user.
The simplest example is if you're bundling an executable - in this case the user can just provide the array elements on the command-line and the corresponding array will be accessible from your application's main method.
Alternatively, if you're writing some kind of webapp, you'd want to accept values in the doGet/doPost method of your application, either by manually parsing query parameters, or by serving the user with an HTML form that submits to your parsing page.
If it's a Swing application you would probably want to pop up a text box for the user to enter input. And in other contexts you may read the values from a database/file, where they have previously been deposited by the user.
Basically, reading input as arrays is quite easy, once you have worked out a way to get input. You need to think about the context in which your application will run, and how your users would likely expect to interact with this type of application, then decide on an I/O architecture that makes sense.

**How to accept array by user Input
Answer:-
import java.io.*;
import java.lang.*;
class Reverse1 {
public static void main(String args[]) throws IOException {
int a[]=new int[25];
int num=0,i=0;
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the Number of element");
num=Integer.parseInt(br.readLine());
System.out.println("Enter the array");
for(i=1;i<=num;i++) {
a[i]=Integer.parseInt(br.readLine());
}
for(i=num;i>=1;i--) {
System.out.println(a[i]);
}
}
}

import java.util.Scanner;
class Example{
//Checks to see if a string is consider an integer.
public static boolean isInteger(String s){
if(s.isEmpty())return false;
for (int i = 0; i <s.length();++i){
char c = s.charAt(i);
if(!Character.isDigit(c) && c !='-')
return false;
}
return true;
}
//Get integer. Prints out a prompt and checks if the input is an integer, if not it will keep asking.
public static int getInteger(String prompt){
Scanner input = new Scanner(System.in);
String in = "";
System.out.println(prompt);
in = input.nextLine();
while(!isInteger(in)){
System.out.println(prompt);
in = input.nextLine();
}
input.close();
return Integer.parseInt(in);
}
public static void main(String[] args){
int [] a = new int[6];
for (int i = 0; i < a.length;++i){
int tmp = getInteger("Enter integer for array_"+i+": ");//Force to read an int using the methods above.
a[i] = tmp;
}
}
}

int length;
Scanner input = new Scanner(System.in);
System.out.println("How many numbers you wanna enter?");
length = input.nextInt();
System.out.println("Enter " + length + " numbers, one by one...");
int[] arr = new int[length];
for (int i = 0; i < arr.length; i++) {
System.out.println("Enter the number " + (i + 1) + ": ");
//Below is the way to collect the element from the user
arr[i] = input.nextInt();
// auto generate the elements
//arr[i] = (int)(Math.random()*100);
}
input.close();
System.out.println(Arrays.toString(arr));

This is my solution if you want to input array in java and no. of input is unknown to you and you don't want to use List<> you can do this.
but be sure user input all those no. in one line seperated by space
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int[] arr = Arrays.stream(br.readLine().trim().split(" ")).mapToInt(Integer::parseInt).toArray();