I have 3 files. Two are preset and aren't allowed to be changed:-
userInputTest (containing "main" method)
import java.util.Arrays;
public class UserInputTest {
public static void main(String[] args) {
UserInput userInput = new UserInput();
//Task 1
System.out.println(userInput.sayHello());
//Task 2
System.out.println(Arrays.toString(userInput.readTenNumbers()));
//Task 3
System.out.println(Arrays.toString(userInput.readTenNames()));
}
}
and 2) userInputTestsAll
import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
class UserInputUnitTestsAll {
UserInput userInput;
#BeforeEach
void createObject() {
userInput = new UserInput();
}
#Test
//Task 1
void testSayHello() {
assertEquals("Hello Suzy".toLowerCase(), userInput.sayHello().toLowerCase());
assertEquals("Hello Bob".toLowerCase(), userInput.sayHello().toLowerCase());
}
#Test
//Task 2
void testReadTenNumbers() {
int[] numbers = {1,2,3,4,5,6,7,8,9,10};
assertArrayEquals(numbers, userInput.readTenNumbers());
int[] numbers1 = {10,20,30,40,50,60,70,80,90,100};
assertArrayEquals(numbers1, userInput.readTenNumbers());
}
#Test
//Task 3
void testReadTenNames() {
String[] names = {"Michael","Saru","Christopher","Sylvia","Paul","Harry","Phillipa","Gabriel","Jett","Ash"};
assertArrayEquals(names, userInput.readTenNames());
}
}
I need to write the 3rd file - called userInput (below), so that when userInputTestsAll is run, my file passes all the test. I have written the following (see code below) but, am getting errors because of the Scanner.close() method. It is for uni work and they insist that we close all Scanner objects after use. I know that closing the Scanner object closes System.in and it can't be reopened. Any suggestions please? When run in Eclipse IDE, the JUnit Failure trace has to come back green.
My code (which can be changed as required):
import java.util.Scanner;
public class UserInput {
// Task 1 - takes user keyboard input. Returns 'Hello' + user input
public String sayHello() {
Scanner keyboard = new Scanner(System.in); // create scanner object to read user inputs
String name = "Something went wrong";
System.out.println("Enter name: ");
name = keyboard.nextLine(); // read user input
keyboard.close(); // close scanner object
return "Hello " + name;
} // End of Task 1
// Task 2 - Reads ten consecutive user integer inputs from keyboard and stores them in an int array. Returns int array
public int[] readTenNumbers() {
Scanner keyboard = new Scanner(System.in); // create scanner object to read user inputs
int [] numbers = new int[10]; // declare array to hold ten integers
for (int i = 0; i < numbers.length; i++) { // loop to read user input each time and assign to numbers array
System.out.println("Enter integer #" + (i+1) + ": ");
numbers[i] = keyboard.nextInt(); // read user input and assign to array
keyboard.nextLine(); // removes 'stray data' (including carriage return, etc)
}
keyboard.close(); // close scanner object
return numbers;
} // End of Task 2
// Task 3 - Reads ten names from user input and stores in a String array. Returns the String array.
public String[] readTenNames() {
Scanner keyboard = new Scanner(System.in); // create scanner object to read user inputs
String[] names = new String[10]; // declare array to hold names
for (int i = 0; i < names.length; i++) { // loop to read user input each time and assign to names array
System.out.println("Enter name #" + (i+1) + ": ");
names[i] = keyboard.nextLine(); // read user input and assign to array
}
keyboard.close(); // close scanner object
return names;
}// End of Task 3
} // End of public class UserInput
I've tried everything I can think of, including putting the scanner object and close method in a seperate method/putting the Scanner.close method just in the last method/etc. T
his is 1st year, 1st semester uni work and the first coding we have had to do on reading user input, so I can't see it needing to be so longwinded/difficult.
So what im trying to do is to use my scanner method to go save the inputs that the users put in thats inside the for loop, but how do i call the certain type of input they place in? What i mean by this is, lets say the user places is in an input of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 as the input for the question method and answer method. In the main method, or any method, how can i call in the input of 10, or 12.
package com.ez.ez;
import java.util.Scanner;
public class ReWrittingBetterCode{
public static void Questions(){
for (int i = 1; i <= 10; i++) {
Scanner scanner = new Scanner(System.in);
System.out.println("Enter a question "+i+"/10");
String firstQuestion = scanner.nextLine();
}
}
public static void Answer() {
for (int i = 1; i <= 10; i++) {
Scanner scanner = new Scanner(System.in);
System.out.println("Enter a answer "+i+"/10");
String answerAnswer = scanner.nextLine();
}
}
public static void main (String[] args) {
Questions();
Answer();
}
}
You need to allocate an array to hold the questions. Then when you prompt for the answers you can repeat the questions. To be consistent with your loops, you should have single variable called noq or something for number of questions, and use that everywhere when you are using for loops.
static int noq = 10;
static String[] questions = new String[noq];
static Scanner scanner = new Scanner(System.in);
public static void main(String[] args) {
Questions();
Answer();
}
public static void Questions() {
for (int i = 1; i <= noq; i++) {
System.out.println("Enter a question " + i + "/" + noq);
String firstQuestion = scanner.nextLine();
questions[i - 1] = firstQuestion;
}
}
public static void Answer() {
for (int i = 1; i <= noq; i++) {
System.out.println(questions[i - 1]);
Scanner scanner = new Scanner(System.in);
System.out.println("Enter a answer " + i + "/" + noq);
String answerAnswer = scanner.nextLine();
}
}
You should also get away from using static everywhere. I had to do it to simplify the example. Check out the Java Tutorials for more information on programming in Java focusing on arrays and the uses of the static keyword.
I attempted to create a calculator, but I can not get it to work because I don't know how to get user input.
How can I get the user input in Java?
One of the simplest ways is to use a Scanner object as follows:
import java.util.Scanner;
Scanner reader = new Scanner(System.in); // Reading from System.in
System.out.println("Enter a number: ");
int n = reader.nextInt(); // Scans the next token of the input as an int.
//once finished
reader.close();
You can use any of the following options based on the requirements.
Scanner class
import java.util.Scanner;
//...
Scanner scan = new Scanner(System.in);
String s = scan.next();
int i = scan.nextInt();
BufferedReader and InputStreamReader classes
import java.io.BufferedReader;
import java.io.InputStreamReader;
//...
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String s = br.readLine();
int i = Integer.parseInt(s);
DataInputStream class
import java.io.DataInputStream;
//...
DataInputStream dis = new DataInputStream(System.in);
int i = dis.readInt();
The readLine method from the DataInputStream class has been deprecated. To get String value, you should use the previous solution with BufferedReader
Console class
import java.io.Console;
//...
Console console = System.console();
String s = console.readLine();
int i = Integer.parseInt(console.readLine());
Apparently, this method does not work well in some IDEs.
You can use the Scanner class or the Console class
Console console = System.console();
String input = console.readLine("Enter input:");
You can get user input using BufferedReader.
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String accStr;
System.out.println("Enter your Account number: ");
accStr = br.readLine();
It will store a String value in accStr so you have to parse it to an int using Integer.parseInt.
int accInt = Integer.parseInt(accStr);
Here is how you can get the keyboard inputs:
Scanner scanner = new Scanner (System.in);
System.out.print("Enter your name");
String name = scanner.next(); // Get what the user types.
The best two options are BufferedReader and Scanner.
The most widely used method is Scanner and I personally prefer it because of its simplicity and easy implementation, as well as its powerful utility to parse text into primitive data.
Advantages of Using Scanner
Easy to use the Scanner class
Easy input of numbers (int, short, byte, float, long and double)
Exceptions are unchecked which is more convenient. It is up to the programmer to be civilized, and specify or catch the exceptions.
Is able to read lines, white spaces, and regex-delimited tokens
Advantages of BufferedInputStream
BufferedInputStream is about reading in blocks of data rather than a single byte at a time
Can read chars, char arrays, and lines
Throws checked exceptions
Fast performance
Synchronized (you cannot share Scanner between threads)
Overall each input method has different purposes.
If you are inputting large amount of data BufferedReader might be
better for you
If you are inputting lots of numbers Scanner does automatic parsing
which is very convenient
For more basic uses I would recommend the Scanner because it is easier to use and easier to write programs with. Here is a quick example of how to create a Scanner. I will provide a comprehensive example below of how to use the Scanner
Scanner scanner = new Scanner (System.in); // create scanner
System.out.print("Enter your name"); // prompt user
name = scanner.next(); // get user input
(For more info about BufferedReader see How to use a BufferedReader and see Reading lines of Chars)
java.util.Scanner
import java.util.InputMismatchException; // import the exception catching class
import java.util.Scanner; // import the scanner class
public class RunScanner {
// main method which will run your program
public static void main(String args[]) {
// create your new scanner
// Note: since scanner is opened to "System.in" closing it will close "System.in".
// Do not close scanner until you no longer want to use it at all.
Scanner scanner = new Scanner(System.in);
// PROMPT THE USER
// Note: when using scanner it is recommended to prompt the user with "System.out.print" or "System.out.println"
System.out.println("Please enter a number");
// use "try" to catch invalid inputs
try {
// get integer with "nextInt()"
int n = scanner.nextInt();
System.out.println("Please enter a decimal"); // PROMPT
// get decimal with "nextFloat()"
float f = scanner.nextFloat();
System.out.println("Please enter a word"); // PROMPT
// get single word with "next()"
String s = scanner.next();
// ---- Note: Scanner.nextInt() does not consume a nextLine character /n
// ---- In order to read a new line we first need to clear the current nextLine by reading it:
scanner.nextLine();
// ----
System.out.println("Please enter a line"); // PROMPT
// get line with "nextLine()"
String l = scanner.nextLine();
// do something with the input
System.out.println("The number entered was: " + n);
System.out.println("The decimal entered was: " + f);
System.out.println("The word entered was: " + s);
System.out.println("The line entered was: " + l);
}
catch (InputMismatchException e) {
System.out.println("\tInvalid input entered. Please enter the specified input");
}
scanner.close(); // close the scanner so it doesn't leak
}
}
Note: Other classes such as Console and DataInputStream are also viable alternatives.
Console has some powerful features such as ability to read passwords, however, is not available in all IDE's (such as Eclipse). The reason this occurs is because Eclipse runs your application as a background process and not as a top-level process with a system console. Here is a link to a useful example on how to implement the Console class.
DataInputStream is primarily used for reading input as a primitive datatype, from an underlying input stream, in a machine-independent way. DataInputStream is usually used for reading binary data. It also provides convenience methods for reading certain data types. For example, it has a method to read a UTF String which can contain any number of lines within them.
However, it is a more complicated class and harder to implement so not recommended for beginners. Here is a link to a useful example how to implement a DataInputStream.
You can make a simple program to ask for user's name and print what ever the reply use inputs.
Or ask user to enter two numbers and you can add, multiply, subtract, or divide those numbers and print the answers for user inputs just like a behavior of a calculator.
So there you need Scanner class. You have to import java.util.Scanner; and in the code you need to use
Scanner input = new Scanner(System.in);
Input is a variable name.
Scanner input = new Scanner(System.in);
System.out.println("Please enter your name : ");
s = input.next(); // getting a String value
System.out.println("Please enter your age : ");
i = input.nextInt(); // getting an integer
System.out.println("Please enter your salary : ");
d = input.nextDouble(); // getting a double
See how this differs: input.next();, i = input.nextInt();, d = input.nextDouble();
According to a String, int and a double varies same way for the rest. Don't forget the import statement at the top of your code.
Also see the blog post "Scanner class and getting User Inputs".
To read a line or a string, you can use a BufferedReader object combined with an InputStreamReader one as follows:
BufferedReader bufferReader = new BufferedReader(new InputStreamReader(System.in));
String inputLine = bufferReader.readLine();
Here, the program asks the user to enter a number. After that, the program prints the digits of the number and the sum of the digits.
import java.util.Scanner;
public class PrintNumber {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int num = 0;
int sum = 0;
System.out.println(
"Please enter a number to show its digits");
num = scan.nextInt();
System.out.println(
"Here are the digits and the sum of the digits");
while (num > 0) {
System.out.println("==>" + num % 10);
sum += num % 10;
num = num / 10;
}
System.out.println("Sum is " + sum);
}
}
Here is your program from the question using java.util.Scanner:
import java.util.Scanner;
public class Example {
public static void main(String[] args) {
int input = 0;
System.out.println("The super insano calculator");
System.out.println("enter the corrosponding number:");
Scanner reader3 = new Scanner(System.in);
System.out.println(
"1. Add | 2. Subtract | 3. Divide | 4. Multiply");
input = reader3.nextInt();
int a = 0, b = 0;
Scanner reader = new Scanner(System.in);
System.out.println("Enter the first number");
// get user input for a
a = reader.nextInt();
Scanner reader1 = new Scanner(System.in);
System.out.println("Enter the scend number");
// get user input for b
b = reader1.nextInt();
switch (input){
case 1: System.out.println(a + " + " + b + " = " + add(a, b));
break;
case 2: System.out.println(a + " - " + b + " = " + subtract(a, b));
break;
case 3: System.out.println(a + " / " + b + " = " + divide(a, b));
break;
case 4: System.out.println(a + " * " + b + " = " + multiply(a, b));
break;
default: System.out.println("your input is invalid!");
break;
}
}
static int add(int lhs, int rhs) { return lhs + rhs; }
static int subtract(int lhs, int rhs) { return lhs - rhs; }
static int divide(int lhs, int rhs) { return lhs / rhs; }
static int multiply(int lhs, int rhs) { return lhs * rhs; }
}
Scanner input = new Scanner(System.in);
String inputval = input.next();
Scanner input=new Scanner(System.in);
int integer=input.nextInt();
String string=input.next();
long longInteger=input.nextLong();
Just one extra detail. If you don't want to risk a memory/resource leak, you should close the scanner stream when you are finished:
myScanner.close();
Note that java 1.7 and later catch this as a compile warning (don't ask how I know that :-)
Here is a more developed version of the accepted answer that addresses two common needs:
Collecting user input repeatedly until an exit value has been entered
Dealing with invalid input values (non-integers in this example)
Code
package inputTest;
import java.util.Scanner;
import java.util.InputMismatchException;
public class InputTest {
public static void main(String args[]) {
Scanner reader = new Scanner(System.in);
System.out.println("Please enter integers. Type 0 to exit.");
boolean done = false;
while (!done) {
System.out.print("Enter an integer: ");
try {
int n = reader.nextInt();
if (n == 0) {
done = true;
}
else {
// do something with the input
System.out.println("\tThe number entered was: " + n);
}
}
catch (InputMismatchException e) {
System.out.println("\tInvalid input type (must be an integer)");
reader.nextLine(); // Clear invalid input from scanner buffer.
}
}
System.out.println("Exiting...");
reader.close();
}
}
Example
Please enter integers. Type 0 to exit.
Enter an integer: 12
The number entered was: 12
Enter an integer: -56
The number entered was: -56
Enter an integer: 4.2
Invalid input type (must be an integer)
Enter an integer: but i hate integers
Invalid input type (must be an integer)
Enter an integer: 3
The number entered was: 3
Enter an integer: 0
Exiting...
Note that without nextLine(), the bad input will trigger the same exception repeatedly in an infinite loop. You might want to use next() instead depending on the circumstance, but know that input like this has spaces will generate multiple exceptions.
import java.util.Scanner;
class Daytwo{
public static void main(String[] args){
System.out.println("HelloWorld");
Scanner reader = new Scanner(System.in);
System.out.println("Enter the number ");
int n = reader.nextInt();
System.out.println("You entered " + n);
}
}
Add throws IOException beside main(), then
DataInputStream input = new DataInputStream(System.in);
System.out.print("Enter your name");
String name = input.readLine();
It is very simple to get input in java, all you have to do is:
import java.util.Scanner;
class GetInputFromUser
{
public static void main(String args[])
{
int a;
float b;
String s;
Scanner in = new Scanner(System.in);
System.out.println("Enter a string");
s = in.nextLine();
System.out.println("You entered string " + s);
System.out.println("Enter an integer");
a = in.nextInt();
System.out.println("You entered integer " + a);
System.out.println("Enter a float");
b = in.nextFloat();
System.out.println("You entered float " + b);
}
}
import java.util.Scanner;
public class Myapplication{
public static void main(String[] args){
Scanner in = new Scanner(System.in);
int a;
System.out.println("enter:");
a = in.nextInt();
System.out.println("Number is= " + a);
}
}
You can get user input like this using a BufferedReader:
InputStreamReader inp = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(inp);
// you will need to import these things.
This is how you apply them
String name = br.readline();
So when the user types in his name into the console, "String name" will store that information.
If it is a number you want to store, the code will look like this:
int x = Integer.parseInt(br.readLine());
Hop this helps!
Can be something like this...
public static void main(String[] args) {
Scanner reader = new Scanner(System.in);
System.out.println("Enter a number: ");
int i = reader.nextInt();
for (int j = 0; j < i; j++)
System.out.println("I love java");
}
You can get the user input using Scanner. You can use the proper input validation using proper methods for different data types like next() for String or nextInt() for Integer.
import java.util.Scanner;
Scanner scanner = new Scanner(System.in);
//reads the input until it reaches the space
System.out.println("Enter a string: ");
String str = scanner.next();
System.out.println("str = " + str);
//reads until the end of line
String aLine = scanner.nextLine();
//reads the integer
System.out.println("Enter an integer num: ");
int num = scanner.nextInt();
System.out.println("num = " + num);
//reads the double value
System.out.println("Enter a double: ");
double aDouble = scanner.nextDouble();
System.out.println("double = " + aDouble);
//reads the float value, long value, boolean value, byte and short
double aFloat = scanner.nextFloat();
long aLong = scanner.nextLong();
boolean aBoolean = scanner.nextBoolean();
byte aByte = scanner.nextByte();
short aShort = scanner.nextShort();
scanner.close();
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
System.out.println("Welcome to the best program in the world! ");
while (true) {
System.out.print("Enter a query: ");
Scanner scan = new Scanner(System.in);
String s = scan.nextLine();
if (s.equals("q")) {
System.out.println("The program is ending now ....");
break;
} else {
System.out.println("The program is running...");
}
}
}
}
This is a simple code that uses the System.in.read() function. This code just writes out whatever was typed. You can get rid of the while loop if you just want to take input once, and you could store answers in a character array if you so choose.
package main;
import java.io.IOException;
public class Root
{
public static void main(String[] args)
{
new Root();
}
public Root()
{
while(true)
{
try
{
for(int y = 0; y < System.in.available(); ++y)
{
System.out.print((char)System.in.read());
}
}
catch(IOException ex)
{
ex.printStackTrace(System.out);
break;
}
}
}
}
I like the following:
public String readLine(String tPromptString) {
byte[] tBuffer = new byte[256];
int tPos = 0;
System.out.print(tPromptString);
while(true) {
byte tNextByte = readByte();
if(tNextByte == 10) {
return new String(tBuffer, 0, tPos);
}
if(tNextByte != 13) {
tBuffer[tPos] = tNextByte;
++tPos;
}
}
}
and for example, I would do:
String name = this.readLine("What is your name?")
Keyboard entry using Scanner is possible, as others have posted. But in these highly graphic times it is pointless making a calculator without a graphical user interface (GUI).
In modern Java this means using a JavaFX drag-and-drop tool like Scene Builder to lay out a GUI that resembles a calculator's console.
Note that using Scene Builder is intuitively easy and demands no additional Java skill for its event handlers that what you already may have.
For user input, you should have a wide TextField at the top of the GUI console.
This is where the user enters the numbers that they want to perform functions on.
Below the TextField, you would have an array of function buttons doing basic (i.e. add/subtract/multiply/divide and memory/recall/clear) functions.
Once the GUI is lain out, you can then add the 'controller' references that link each button function to its Java implementation, e.g a call to method in your project's controller class.
This video is a bit old but still shows how easy Scene Builder is to use.
The most simple way to get user input would be to use Scanner. Here's an example of how it's supposed to be used:
import java.util.Scanner;
public class main {
public static void main(String[]args) {
Scanner sc=new Scanner(System.in);
int a;
String b;
System.out.println("Type an integer here: ");
a=sc.nextInt();
System.out.println("Type anything here:");
b=sc.nextLine();
The line of code import java.util.Scanner; tells the program that the programmer will be using user inputs in their code. Like it says, it imports the scanner utility. Scanner sc=new Scanner(System.in); tells the program to start the user inputs. After you do that, you must make a string or integer without a value, then put those in the line a=sc.nextInt(); or a=sc.nextLine();. This gives the variables the value of the user inputs. Then you can use it in your code. Hope this helps.
Using JOptionPane you can achieve it.
Int a =JOptionPane.showInputDialog(null,"Enter number:");
import java.util.Scanner;
public class userinput {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Name : ");
String name = input.next();
System.out.print("Last Name : ");
String lname = input.next();
System.out.print("Age : ");
byte age = input.nextByte();
System.out.println(" " );
System.out.println(" " );
System.out.println("Firt Name: " + name);
System.out.println("Last Name: " + lname);
System.out.println(" Age: " + age);
}
}
class ex1 {
public static void main(String args[]){
int a, b, c;
a = Integer.parseInt(args[0]);
b = Integer.parseInt(args[1]);
c = a + b;
System.out.println("c = " + c);
}
}
// Output
javac ex1.java
java ex1 10 20
c = 30
This question already has answers here:
How to test for blank line with Java Scanner?
(5 answers)
Closed 3 years ago.
The goal of this is to let the user enter a number per line and when the user no longer wish to continue they should be able to enter a empty line and when that happens the program should you give you a message with the largest number.
Problem is I can't make the loop break with an empty line. I'm not sure how to. I've checked other questions for a solution but I couldn't find anything that helped. I also can't assign scan.hasNextInt() == null....
I'm sure there is a quick and logical solution to this that I'm not thinking of.
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Enter a number and press [Enter] per line, when you no longer wish to continue press [Enter] with no input.(empty line)");
int x = 0;
while(scan.hasNextInt()){
int n = scan.nextInt();
if (n > x){
x = n;
}
}
System.out.println("Largets number entered: " + x);
}
}
This should solve your problem:
import java.util.Scanner;
public class StackOverflow {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Enter a number and press [Enter] per line, when you no longer wish to continue press [Enter] with no input.(empty line)");
int x = 0;
try {
while(!scan.nextLine().isEmpty()){
int num = Integer.parseInt(scan.nextLine());
if(num > x) {
x = num;
}
}
} catch (NumberFormatException e) {
e.printStackTrace();
}
System.out.println("Largest number entered: " + x);
scan.close();
}
}
import java.util.*;
public class main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Enter a number and press [Enter] per line, when you no longer wish to continue press [Enter] with no input.");
String str = scanner.nextLine();
int x = 0;
try {
while(!str.isEmpty()){
int number = Integer.parseInt(str);
if (number > x){
x = number;
}
str = scanner.nextLine();
}
}
catch (NumberFormatException e) {
System.out.println("There was an exception. You entered a data type other than Integer");
}
System.out.println("Largets number entered: " + x);
}
}
Let's say I have a text file with this:
2 4 6 7 -999
9 9 9 9 -999
When I run the program, I should print out everything except the "-999" on each line. What I should get is:
2 4 6 7
9 9 9 9
This is what I've tried:
public class Prac {
public static void main(String[] args) throws FileNotFoundException {
Scanner reader = new Scanner(new File("test.txt"));
while(reader.hasNextLine() && reader.nextInt() != -999) {
int nextInt = reader.nextInt();
System.out.print(nextInt + " ");
}
}
}
I've tried using while/for loops but don't seem to get this to work and the numbers are not on different lines. I don't get why the condition does not work when I run the code and each line is not separated while printing. I've been trying to find a solution for a while and decided to ask here. It's probably an easy question but I haven't coded in a while, so let me know. Thanks in advance.
The reader.nextInt() in the while will consume the next int, so you will be always skipping an integer. So I would suggest:
public static void main(String[] args) throws FileNotFoundException {
Scanner reader = new Scanner(new File("test.txt"));
while (reader.hasNextLine()) {
int nextInt = reader.nextInt();
if (nextInt != -999)
System.out.print(nextInt + " ");
else
System.out.println();
}
}
Update: In case you want to calculate the average for each line, as requested in your comment, you could store each value to make the calculations (see here other ways). The code below will do that and print the average at the end of the line:
public static void main(String[] args) throws FileNotFoundException {
Scanner reader = new Scanner(new File("test.txt"));
List<Integer> values = new ArrayList<>();
while (reader.hasNextLine()) {
int nextInt = reader.nextInt();
if (nextInt != -999) {
System.out.print(nextInt + " ");
values.add(nextInt);
} else {
int sum = 0;
for (int value : values) {
sum += value;
}
System.out.println((float) sum / values.size());
values.clear();
}
}
}
Try this.
public static void main(String[] args) throws FileNotFoundException {
Scanner reader = new Scanner(new File("./input.txt"));
while (reader.hasNextInt()) {
int nextInt = reader.nextInt();
if (nextInt != -999) {
System.out.print(nextInt + " ");
} else {
if (reader.hasNextLine()) {
System.out.println("");
}
}
}
}
I'm late to the party ... but as long as somebody else replied after you accepted, I thought I'd share the response I started writing ... but was too slow to post back before you got two other (great!) responses.
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Prac {
static final int EOL = -999;
public static void main(String[] args) throws FileNotFoundException {
File f = new File("test.txt");
try (Scanner reader = new Scanner(f)) {
int nextInt;
while(reader.hasNext()) {
if ((nextInt = reader.nextInt()) == EOL)
System.out.println();
else
System.out.print(nextInt + " ");
}
}
}
}
NOTES:
1. The main problem is that you didn't capture the value of "scanner.nextInt()" in your while loop. Consequently, you skipped every other value.
There's also a resource leak - you're not closing the Scanner. That doesn't matter for a small program like this (exiting the program will close the file just fine ;)).
One way is to do an explicit "close()".
Another alternative, illustrated above, is the try-with-resources statement, introduced in Java 8.
Problem is you're not saving the value from reader.nextInt() in your while Loop.
You can try this:
while (reader.hasNextLine()) {
int nextInt = reader.nextInt();
System.out.print( nextInt != -999 ? nextInt + " " : "\n");
}