What s the difference between next and nextLine methods from Scanner class

Question

What is the main difference between next   and nextLine    My main goal is to read the all text using a Scanner which may be  connected  to any source  file for example    Which one should I choose and why

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Just for another example of Scanner next   and nextLine   is that  like below   nextLine   does not let user type while next   makes Scanner wait and read the input    Scanner sc   new Scanner System in     do       System out println  The values on dice are          for int i   0  i  lt  n  i              System out println ran nextInt 6    1             System out println  Continue   yes or no       while sc next   equals  yes        while sc nextLine   equals  yes

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I also got a problem concerning a delimiter  the question was all about inputs of   enter your name  enter your age  enter your email  enter your address    The problem   I finished successfully with name  age  and email  When I came up with the address of two words having a whitespace  Harnet street  I just got the first one  harnet     The solution  I used the delimiter for my scanner and went out successful   Example    public static void main  String args            Initialize the Scanner this way so that it delimits input using a new line character      Scanner s   new Scanner System in  useDelimiter   n        System out println  Enter Your Name          String name   s next        System out println  Enter Your Age          int age   s nextInt        System out println  Enter Your E-mail          String email   s next        System out println  Enter Your Address          String address   s next         System out println  Name    name       System out println  Age    age       System out println  E-mail    email       System out println  Address    address

User · Answer

The basic difference is next   is used for gettting the input till the delimiter is encountered By default it is whitespace but you can also change it  and return the token which you have entered The cursor then remains on the Same line Whereas in nextLine   it scans the input till we hit enter button and return the whole thing and places the cursor in the next line                 Scanner sc new Scanner System in           String s   new String 2           for int i 0 i lt 2 i                 s i  sc next                      for int j 0 j lt 2 j                          System out println  The string at position   j    is   s j                    Try running this code by giving Input as  Hello World  The scanner reads the input till  o  and then a delimiter occurs so s 0  will be  Hello  and cursor will be pointing to the next position after delimiter that is  W  in our case  and when s 1  is read it scans the  World  and return it to s 1  as the next complete token by definition of Scanner  If we use nextLine   instead it will read the  Hello World  fully and also more till we hit the enter button and store it in s 0   We may give another string also by using nextLine    I recommend you to try using this example and more and ask for any clarification

User · Answer

The key point is to find where the method will stop and where the cursor will be after calling the methods   All methods will read information which does not include whitespace between the cursor position and the next default delimiters whitespace  tab   n--created by pressing Enter   The cursor stops before the delimiters except for nextLine    which reads information  including whitespace created by delimiters  between the cursor position and  n  and the cursor stops behind  n     For example  consider the following illustration    23 24 25 26 27 n     -  the current cursor position    -  whitespace  stream -  Bold  the information got by the calling method   See what happens when you call these methods   nextInt         read 23  24 25 26 27 n  nextDouble     read 23 24  25 26 27 n  next     read 23 24 25  26 27 n  nextLine     read 23 24 25 26 27 n     After this  the method should be called depending on your requirement

User · Answer

From javadocs  next   Returns the next token if it matches the pattern constructed from the specified string  nextLine   Advances this scanner past the current line and returns the input that was skipped   Which one you choose depends which suits your needs best  If it were me reading a whole file I would go for nextLine until I had all the file

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I always prefer to read input using nextLine   and then parse the string   Using next   will only return what comes before the delimiter  defaults to whitespace   nextLine   automatically moves the scanner down after returning the current line   A useful tool for parsing data from nextLine   would be str split    s      String data   scanner nextLine    String   pieces   data split    s        Parse the pieces   For more information regarding the Scanner class or String class refer to the following links   Scanner  http   docs oracle com javase 7 docs api java util Scanner html  String  http   docs oracle com javase 7 docs api java lang String html

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From the documentation for Scanner      A Scanner breaks its input into tokens using a delimiter pattern  which by default matches whitespace    From the documentation for next        A complete token is preceded and followed by input that matches the delimiter pattern

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Both functions are used to move to the next Scanner token   The difference lies in how the scanner token is generated     next   generates scanner tokens using delimiter as White Space      nextLine   generates scanner tokens using delimiter as   n   i e Enter   key presses

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A scanner breaks its input into tokens using a delimiter pattern  which is by default known the Whitespaces   Next   uses to read a single word and when it gets a white space it stops reading and the cursor back to its original position  NextLine   while this one reads a whole word even when it meets a whitespace the cursor stops when it finished reading and cursor backs to the end of the line  so u don t need to use a delimeter when you want to read a full word as a sentence you just need to use NextLine        public static void main String   args                   TODO code application logic here            String str              Scanner input   new Scanner  System in                str input nextLine                System out println str

User · Answer

next   and nextLine   methods are associated with Scanner and is used for getting String inputs  Their differences are     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   import java util Scanner   public class temp       public static void main String arg                  Scanner sc new Scanner System in           System out println  enter string for c            String c sc next            System out println  c is   c           System out println  enter string for d            String d sc next            System out println  d is   d             Output   enter string for c abc def c is abc  enter string for d  d is  def  If you use nextLine   instead of next   then   Output   enter string for c  ABC DEF c is ABC DEF enter string for d  GHI d is GHI

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next   can read the input only till the space  It can t read two words separated by a 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   For reading the entire line you can use nextLine

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From JavaDoc          A Scanner breaks its input into tokens using a delimiter pattern  which by default matches whitespace    next    Finds and returns the next complete token from this scanner    nextLine    Advances this scanner past the current line and returns the input that was skipped       So in case of  small example lt eol gt text  next   should return  small  and nextLine   should return  small example

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In short  if you are inputting a string array of length t  then Scanner nextLine   expects t lines  each entry in the string array is differentiated from the other by enter key And Scanner next   will keep taking inputs till you press enter but stores string word  inside the array  which is separated by whitespace   Lets have a look at following snippet of code       Scanner in   new Scanner System in       int t   in nextInt        String   s   new String t        for  int i   0  i  lt  t  i              s i    in next            when I run above snippet of code in my IDE  lets say for string length 2  it does not matter whether I enter my string as  Input as  - abcd abcd  or  Input as  -   abcd  abcd   Output will be like abcd  abcd  But if in same code we replace next   method by nextLine        Scanner in   new Scanner System in       int t   in nextInt        String   s   new String t        for  int i   0  i  lt  t  i              s i    in nextLine            Then if you enter input on prompt as - abcd abcd   Output is  -  abcd abcd  and if you enter the input on prompt as  abcd  and if you press enter to enter next abcd in another line  the input prompt will just exit and you will get the output   Output is -  abcd

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What I have noticed apart from  next   scans only upto space where as nextLine   scans the entire line is that next waits till it gets a complete token where as nextLine   does not wait for complete token  when ever   n  is obtained i e when you press enter key  the scanner cursor moves to the next line and returns the previous line skipped  It does not check for the whether you have given complete input or not  even it will take an empty string where as next   does not take empty string  public class ScannerTest        public static void main String   args             Scanner sc   new Scanner System in           int cases   sc nextInt            String   str   new String cases           for int i 0 i lt cases i                 str i  sc next                          Try this program by changing the next   and nextLine   in for loop  go on pressing   n  that is enter key without any input  you can find that using nextLine   method it terminates after pressing given number of cases where as next   doesnot terminate untill you provide and input to it for the given number of cases

[java] What's the difference between next() and nextLine() methods from Scanner class?

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