I am writing a simple code that takes number,name,surname from the user with scanner.
But when user enters name with spaces in it(two or more names) the code thinks string after the first space is surname.
I tried using input.nextLine(); in that case it skipped name completely and took only surname from the user.
Scanner input = new Scanner(System.in);
System.out.println("Enter number");
int num = input.nextInt();
System.out.println("Enter Name");
String name = input.next();
System.out.println("Enter Surname");
String surname = input.next();
Try this:
Scanner input = new Scanner(System.in);
System.out.println("Enter number");
int num=input.nextInt();
input.nextLine(); // add this
System.out.println("Enter Name");
String name=input.nextLine();
System.out.println("Enter Surname");
String surname=input.nextLine();
System.out.println(num + " - " + name + " - " + surname);
Sample input/output:
Enter number
1
Enter Name
user name
Enter Surname
sur name
1 - user name - sur name
Use sc.nextLine() instead of sc.next() to read String with spaces
Here is my updated code. Again, the instructions are as follows: "Enter a first name, last name, student id, and avg, then have those 4 things displayed in a new csv file, with each of the 4 inputs separated by a comma in each record." This code works well, is there anything I can do better? Also, is "in.close()" necessary in this case since I am not reading a file, but rather user input?
public class Homework07 {
public static void main(String[] args) throws FileNotFoundException {
System.out.println("Welcome! This program will store student records that you enter.");
System.out.println("When you are done entering student records, simply type in 'Done' .");
Scanner in = new Scanner(System.in);
PrintWriter outFile = new PrintWriter("students.csv");
while (true) {
System.out.print("Please enter the first name: ");
String firstName = in.nextLine();
if (firstName.equals("Done")) {
break;
}
System.out.print("Please enter the last name: ");
String lastName = in.nextLine();
System.out.print("Please enter the student ID: ");
int studentId = in.nextInt();
System.out.print("Please enter the current average: ");
double currentAvg = in.nextDouble();
in.nextLine();
String newRecord = (firstName + ", " + lastName + ", " + studentId + ", " + currentAvg);
outFile.println(newRecord);
}
in.close();
outFile.close();
}
}
your code capture the enter key entered by user to I added an empty in.nextLine(); to escape it, and secondly I added outFile.flush(); to flush the stream to the file.
System.out.println("Welcome! This program will store student records that you enter.");
System.out.println("When you are done entering student records, simply type in 'Done' .");
Scanner in = new Scanner(System.in);
PrintWriter outFile = new PrintWriter("students.csv");
while (true) {
System.out.print("Please enter the first name: ");
String firstName = in.nextLine();
if (firstName.equals("Done")) {
break;
}
System.out.print("Please enter the last name: ");
String lastName = in.nextLine();
System.out.print("Please enter the student ID: ");
int studentId = in.nextInt();
System.out.print("Please enter the current average: ");
double currentAvg = in.nextDouble();
in.nextLine();
outFile.write(firstName + "," + lastName + "," + studentId + "," + currentAvg);
outFile.flush();
}
in.close();
outFile.close();
Your call to the Scanner#nextDouble() method does not consume the ENTER key hit (the newline character) therefore you need to do it yourself by placing this line: in.nextLine(); directly under this line:
double currentAvg = in.nextDouble();
Ironically, you need to apply a newline character when you write to your file for every record you want to save, like this:
String record = new StringBuilder(firstName).append(", ").append(lastName)
.append(", ").append(studentId).append(", ")
.append(currentAvg).append(System.lineSeparator())
.toString();
outFile.write(record);
How could I read input from the console using the Scanner class? Something like this:
System.out.println("Enter your username: ");
Scanner = input(); // Or something like this, I don't know the code
Basically, all I want is have the scanner read an input for the username, and assign the input to a String variable.
A simple example to illustrate how java.util.Scanner works would be reading a single integer from System.in. It's really quite simple.
Scanner sc = new Scanner(System.in);
int i = sc.nextInt();
To retrieve a username I would probably use sc.nextLine().
System.out.println("Enter your username: ");
Scanner scanner = new Scanner(System.in);
String username = scanner.nextLine();
System.out.println("Your username is " + username);
You could also use next(String pattern) if you want more control over the input, or just validate the username variable.
You'll find more information on their implementation in the API Documentation for java.util.Scanner
Scanner scan = new Scanner(System.in);
String myLine = scan.nextLine();
Reading Data From The Console
BufferedReader is synchronized, so read operations on a BufferedReader can be safely done from multiple threads. The buffer size may be specified, or the default size(8192) may be used. The default is large enough for most purposes.
readLine() « just reads data line by line from the stream or source. A line is considered to be terminated by any one these: \n, \r (or) \r\n
Scanner breaks its input into tokens using a delimiter pattern, which by default matches whitespace(\s) and it is recognised by Character.isWhitespace.
« Until the user enters data, the scanning operation may block, waiting for input.
« Use Scanner(BUFFER_SIZE = 1024) if you want to parse a specific type of token from a stream.
« A scanner however is not thread safe. It has to be externally synchronized.
next() « Finds and returns the next complete token from this scanner.
nextInt() « Scans the next token of the input as an int.
Code
String name = null;
int number;
java.io.BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
name = in.readLine(); // If the user has not entered anything, assume the default value.
number = Integer.parseInt(in.readLine()); // It reads only String,and we need to parse it.
System.out.println("Name " + name + "\t number " + number);
java.util.Scanner sc = new Scanner(System.in).useDelimiter("\\s");
name = sc.next(); // It will not leave until the user enters data.
number = sc.nextInt(); // We can read specific data.
System.out.println("Name " + name + "\t number " + number);
// The Console class is not working in the IDE as expected.
java.io.Console cnsl = System.console();
if (cnsl != null) {
// Read a line from the user input. The cursor blinks after the specified input.
name = cnsl.readLine("Name: ");
System.out.println("Name entered: " + name);
}
Inputs and outputs of Stream
Reader Input: Output:
Yash 777 Line1 = Yash 777
7 Line1 = 7
Scanner Input: Output:
Yash 777 token1 = Yash
token2 = 777
There is problem with the input.nextInt() method - it only reads the int value.
So when reading the next line using input.nextLine() you receive "\n", i.e. the Enter key. So to skip this you have to add the input.nextLine().
Try it like that:
System.out.print("Insert a number: ");
int number = input.nextInt();
input.nextLine(); // This line you have to add (it consumes the \n character)
System.out.print("Text1: ");
String text1 = input.nextLine();
System.out.print("Text2: ");
String text2 = input.nextLine();
There are several ways to get input from the user. Here in this program we will take the Scanner class to achieve the task. This Scanner class comes under java.util, hence the first line of the program is import java.util.Scanner; which allows the user to read values of various types in Java. The import statement line should have to be in the first line the java program, and we proceed further for code.
in.nextInt(); // It just reads the numbers
in.nextLine(); // It get the String which user enters
To access methods in the Scanner class create a new scanner object as "in". Now we use one of its method, that is "next". The "next" method gets the string of text that a user enters on the keyboard.
Here I'm using in.nextLine(); to get the String which the user enters.
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 ScannerDemo {
public static void main(String[] arguments){
Scanner input = new Scanner(System.in);
String username;
double age;
String gender;
String marital_status;
int telephone_number;
// Allows a person to enter his/her name
Scanner one = new Scanner(System.in);
System.out.println("Enter Name:" );
username = one.next();
System.out.println("Name accepted " + username);
// Allows a person to enter his/her age
Scanner two = new Scanner(System.in);
System.out.println("Enter Age:" );
age = two.nextDouble();
System.out.println("Age accepted " + age);
// Allows a person to enter his/her gender
Scanner three = new Scanner(System.in);
System.out.println("Enter Gender:" );
gender = three.next();
System.out.println("Gender accepted " + gender);
// Allows a person to enter his/her marital status
Scanner four = new Scanner(System.in);
System.out.println("Enter Marital status:" );
marital_status = four.next();
System.out.println("Marital status accepted " + marital_status);
// Allows a person to enter his/her telephone number
Scanner five = new Scanner(System.in);
System.out.println("Enter Telephone number:" );
telephone_number = five.nextInt();
System.out.println("Telephone number accepted " + telephone_number);
}
}
You can make a simple program to ask for the user's name and print whatever the reply use inputs.
Or ask the user to enter two numbers and you can add, multiply, subtract, or divide those numbers and print the answers for user inputs just like the behavior of a calculator.
So there you need the 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 the same way for the rest. Don't forget the import statement at the top of your code.
A simple example:
import java.util.Scanner;
public class Example
{
public static void main(String[] args)
{
int number1, number2, sum;
Scanner input = new Scanner(System.in);
System.out.println("Enter First multiple");
number1 = input.nextInt();
System.out.println("Enter second multiple");
number2 = input.nextInt();
sum = number1 * number2;
System.out.printf("The product of both number is %d", sum);
}
}
When the user enters his/her username, check for valid entry also.
java.util.Scanner input = new java.util.Scanner(System.in);
String userName;
final int validLength = 6; // This is the valid length of an user name
System.out.print("Please enter the username: ");
userName = input.nextLine();
while(userName.length() < validLength) {
// If the user enters less than validLength characters
// ask for entering again
System.out.println(
"\nUsername needs to be " + validLength + " character long");
System.out.print("\nPlease enter the username again: ");
userName = input.nextLine();
}
System.out.println("Username is: " + userName);
To read input:
Scanner scanner = new Scanner(System.in);
String input = scanner.nextLine();
To read input when you call a method with some arguments/parameters:
if (args.length != 2) {
System.err.println("Utilizare: java Grep <fisier> <cuvant>");
System.exit(1);
}
try {
grep(args[0], args[1]);
} catch (IOException e) {
System.out.println(e.getMessage());
}
import java.util.*;
class Ss
{
int id, salary;
String name;
void Ss(int id, int salary, String name)
{
this.id = id;
this.salary = salary;
this.name = name;
}
void display()
{
System.out.println("The id of employee:" + id);
System.out.println("The name of employye:" + name);
System.out.println("The salary of employee:" + salary);
}
}
class employee
{
public static void main(String args[])
{
Scanner sc = new Scanner(System.in);
Ss s = new Ss(sc.nextInt(), sc.nextInt(), sc.nextLine());
s.display();
}
}
Here is the complete class which performs the required operation:
import java.util.Scanner;
public class App {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
final int valid = 6;
Scanner one = new Scanner(System.in);
System.out.println("Enter your username: ");
String s = one.nextLine();
if (s.length() < valid) {
System.out.println("Enter a valid username");
System.out.println(
"User name must contain " + valid + " characters");
System.out.println("Enter again: ");
s = one.nextLine();
}
System.out.println("Username accepted: " + s);
Scanner two = new Scanner(System.in);
System.out.println("Enter your age: ");
int a = two.nextInt();
System.out.println("Age accepted: " + a);
Scanner three = new Scanner(System.in);
System.out.println("Enter your sex: ");
String sex = three.nextLine();
System.out.println("Sex accepted: " + sex);
}
}
There is a simple way to read from the console.
Please find the below code:
import java.util.Scanner;
public class ScannerDemo {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
// Reading of Integer
int number = sc.nextInt();
// Reading of String
String str = sc.next();
}
}
For a detailed understanding, please refer to the below documents.
Doc
Now let's talk about the detailed understanding of the Scanner class working:
public Scanner(InputStream source) {
this(new InputStreamReader(source), WHITESPACE_PATTERN);
}
This is the constructor for creating the Scanner instance.
Here we are passing the InputStream reference which is nothing but a System.In. Here it opens the InputStream Pipe for console input.
public InputStreamReader(InputStream in) {
super(in);
try {
sd = StreamDecoder.forInputStreamReader(in, this, (String)null); // ## Check lock object
}
catch (UnsupportedEncodingException e) {
// The default encoding should always be available
throw new Error(e);
}
}
By passing the System.in this code will opens the socket for reading from console.
You can flow this code:
Scanner obj= new Scanner(System.in);
String s = obj.nextLine();
You can use the Scanner class in Java
Scanner scan = new Scanner(System.in);
String s = scan.nextLine();
System.out.println("String: " + s);
import java.util.Scanner; // Import the Scanner class
class Main { // Main is the class name
public static void main(String[] args) {
Scanner myObj = new Scanner(System.in); // Create a Scanner object
System.out.println("Enter username");
String userName = myObj.nextLine(); // Read user input
System.out.println("Username is: " + userName); // Output user input
}
}
you have wrote
Scanner = input()
this is wrong method, you have to make an integer or a string, i would like to prefer string, and then give a string any name that can be i that can be n or anything else, remember that you are giving name to username you can also give name username also, and the code is
String username = sc.nextline();
System.our.println("the username is" + username);
I hope you understand now
I am a new java programmer, In my below code when am trying to enter the employee name like john smith, only john is getting printed in output.
And if I put
System.out.print("Enter Employee Name: ");
String employeeName = s.next();
above
System.out.print("Enter SEX: ");
char SEX = s.next().charAt(0);
this piece of code in output is not asking for my employeename value. and directly printing the remaining values.
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
**package cs480;
import java.util.Scanner;
public class CS480D1_Richa_2_Week2 {
public static void main(String [] args){
Scanner s=new Scanner(System.in);
System.out.print("Ente Employee ID: ");
int employeeId = s.nextInt();
System.out.print("Ente SEX: ");
char SEX = s.next().charAt(0);
System.out.print("Ente Employee Name: ");
String employeeName = s.next();
System.out.println("Employee ID is " +employeeId);
System.out.println("Employee Name is " +employeeName);
System.out.println("Employee gender is " +SEX);
}
}**
Please try with this:
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
System.out.print("Ente Employee ID: ");
int employeeId = s.nextInt();
System.out.print("Ente SEX: ");
char SEX = s.next().charAt(0);
System.out.print("Ente Employee Name: ");
String employeeName = s.nextLine();
employeeName = s.nextLine();// Try to add this line of code
System.out.println("Employee ID is " + employeeId);
System.out.println("Employee Name is " + employeeName);
System.out.println("Employee gender is " + SEX);
}
Try replacing your code
String employeeName = scanner.nextLine();
instead
String employeeName = scanner.next();
next() can read the input only till the space. It can't read two words separated by space. Also, next() places the cursor in the same line after reading the input.
nextLine() reads input including space between the words (that is, it reads till the end of line \n). Once the input is read, nextLine() positions the cursor in the next line.
Either you can use
scanner.nextLine()
or override delimiter to use next()
scanner.useDelimiter("\n");
scanner.next();
Scanner.next() uses a white-space delimiter(takes the element before white-space).
So either use
Scanner.nextLine()
or reset the delimiter using
Scanner s = new Scanner(input).useDelimiter("\\s*"your delimiter"\\s*");
I am trying with user input to the values firstname, middlename, lastname, age for by using scanner class, but the below program only takes firstname, middlename, lastname and not the value of age.
public void inputEmployeeDetails(){
Scanner scanner = new Scanner(System.in);
System.out.println("Enter the firstname ");
firstname= scanner.nextLine();
System.out.println("Enter the middlename ");
middlename= scanner.nextLine();
System.out.println("Enter the lastname");
lastname= scanner.nextLine();
System.out.println("Enter the age");
age= scanner.nextInt();
}
I need to take all the values one after the other through the user prompt.
Based on the entered data I am displaying the employee details. Could someone let me know what I am missing.
I would like to also like to take multiple inputs from the user. Please let me know if I am right in the below
System.out.println("Do you like to fetch more records press "Yes" or "No");
String input=scanner.nextLine();
if(input="Yes")
inputEmployeeDetails();
The age variable takes the next ENTER key that you press, so nothing is stored. Since the datatype of ENTER is different than the data type of age variable, hence your code was getting InputMismatchException. You need to check if the next value is an int then assign it to variable. Please refer below once:
import java.util.Scanner;
public class Test{
public static void main(String []args){
String firstname, middlename, lastname;
int age;
Scanner scanner = new Scanner(System.in);
System.out.println("Enter the firstname ");
firstname= scanner.nextLine();
System.out.println("Enter the middlename ");
middlename= scanner.nextLine();
System.out.println("Enter the lastname");
lastname= scanner.nextLine();
System.out.println("Enter the age");
if(scanner.hasNextInt()) {
age= scanner.nextInt();
}else
age = 0;
System.out.println(firstname + " " + middlename + " " + lastname + " " + age);
}
}
Check this program:
String firstname,middlename,lastname,choice;
int age, flag;
Scanner scanner = new Scanner(System.in);
do{
choice=null;
System.out.println("Enter the firstname ");
firstname= scanner.nextLine();
System.out.println("Enter the middlename ");
middlename= scanner.nextLine();
System.out.println("Enter the lastname");
lastname= scanner.nextLine();
System.out.println("Enter the age");
flag=0;age=0;
while(flag==0){
try{
age= scanner.nextInt();
flag=1;
}
catch(Exception e){
scanner.nextLine();
System.out.println("Wrong entry, please enter digits only:");
}
}
System.out.println(firstname+" "+middlename+" "+lastname+" "+age);
System.out.println("Do you like to fetch more records press Yes or No");
scanner.nextLine();
choice=scanner.nextLine();
}while(choice.contains("Y")||choice.contains("y"));
System.out.println("Program terminated.");
scanner.close();
System.exit(0);