How to use readline method in Java

Question

I am beginner in Java  and I was reading the topic of giving values to variables through the readLine   method from the keyboard  The program for that is given in the book is as follows   import java io DataInputStream class Reading       public static void main String args                  DataInputStream in   new DataInputStream System in           int intnumber 0          float floatnumber 0 0f          try               system out println  enter an integer                  intnumber   Integer parseInt in readline                  system out println  enter a float number                  floatnumber   Float valueOf in readline    floatvalue                          Rest of code   I want to ask the following questions    What is done in the following statement   DataInputStream in   new DataInputStream System in     If in is an object of DataInputStream then what is new and what do the statement on the right-hand side of above statement do  Why have different methods been used for putting the integer value into intnumber and float value into floatnumber

User · Answer

A DataInputStream is just a decorator over an InputStream  which System in is  which allows to read using more convenient methods   As to the Float valueOf    well  that s curious because Float has  parseFloat   as well  Here the code grabs a Float with  valueOf   which it turns into the primitive float type using  floatValue    which is unnecessary with Java 1 5  due to auto unboxing   And as other answers rightly say  these methods are obsolete anyway

User · Answer

This will explain it  I think     import java io     class reading       public static void  main String args    throws IOException               float number          System out println  Enter a number            try                       InputStreamReader in   new InputStreamReader System in               BufferedReader br   new BufferedReader in               String a   br readLine                number   Float valueOf a               int x    int number               System out println  Your input     number               System out println  Your input in integer terms is       x                     catch Exception e

User · Answer

I advise you to go with Scanner instead of DataInputStream  Scanner is specifically designed for this purpose and introduced in Java 5  See the following links to know how to use Scanner    Java Documentation Java Tutorial   Example  Scanner s   new Scanner System in   System out println s nextInt     System out println s nextInt     System out println s next     System out println s next

User · Answer

Use BufferedReader and InputStreamReader classes   BufferedReader buffer new BufferedReader new InputStreamReader System in    String line buffer readLine      Or use java util Scanner class methods   Scanner scan new Scanner System in

User · Answer

In summary  I would be careful as to what code you copy  It is possible you are copying code which happens to work  rather than well chosen code      In intnumber  parseInt is used and in floatnumber valueOf is used why so    There is no good reason I can see  It s an inconsistent use of the APIs as you suspect     Java is case sensitive  and there isn t any Readline   method  Perhaps you mean readLine     DataInputStream readLine   is deprecated in favour of using BufferedReader readLine     However  for your case  I would use the Scanner class   Scanner sc   new Scanner System in   int intNum   sc nextInt    float floatNum   sc nextFloat      If you want to know what a class does I suggest you have a quick look at the Javadoc

[java] How to use readline() method in Java?

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