java - Scan close causes trouble so should I leave it unclosed? -

just switching python java , have problems reading in input user. have 2 questions in following code: (1) why not working after close scanner(if after skip close, problem?) (2) why summation of 2 simple numeric numbers lead inaccurate answer 3.0300000000000002?

import java.util.scanner;  public class helloworld {      public static void main(string[] args) {         string s1 = getinput("enter numeric value: ");         string s2 = getinput("enter numeric value: ");          double d1 = double.parsedouble(s1);         double d2 = double.parsedouble(s2);         double result = d1 + d2;          system.out.println("the answer is: " + result);     }      private static string getinput(string prompt){         system.out.print(prompt);         scanner scan = new scanner(system.in);          string input = "default";         try{             input = scan.nextline();         }         catch (exception e){             system.out.println(e.getmessage());         }         //scan.close();         return input;     } } 

this output of commenting out scan close:

enter numeric value: 1.01 enter numeric value: 2.02 answer is: 3.0300000000000002 (weird output) 

if uncomment scan.close(), cannot type int second number , error message attached:

enter numeric value: 1.01 enter numeric value: no line found exception in thread "main" java.lang.numberformatexception: input string: "default"     @ sun.misc.floatingdecimal.readjavaformatstring(floatingdecimal.java:1241)     @ java.lang.double.parsedouble(double.java:540)     @ helloworld.main(helloworld.java:10) 

if of point me right place or give me hints of how 2 problems come from, appreciated!

at end of first input, close the stream. stream closed "standard input stream". scanner closes underlying stream when call close().

all attempts read "standard input stream" fail after first invocation of getinput(string) method.

catching exception bad. return "default" when fails read stream. double.parsedouble(..) complains bad string.