java.util.Scanner second instance throwing NoSuchElementException -


this question has answer here:

why not able read second line on using second instance of scanner? "java.util.nosuchelementexception: no line found".

i understand should use hasnextline() , avoided exception, question why second line not available @ all? also, reason there multiple scanner instances because in reality, scanner being instantiated in method called multiple times, , not looking solution or fix there.

please note not closing either scanners or streams. reading 1 line each using scanners, while have 3 lines in stream.

here program simplified:

private void scanlines() {     string input = "line 1." + system.lineseparator()                   + "line 2." + system.lineseparator()                   + "line 3." + system.lineseparator();      bytearrayinputstream bais = new bytearrayinputstream(input.getbytes());      scanner scanner1 = new scanner(bais);     system.out.println(scanner1.nextline());      scanner scanner2 = new scanner(bais);     system.out.println(scanner2.nextline()); }

output is:

line 1. exception in thread "main" java.util.nosuchelementexception: no line found         @ java.util.scanner.nextline(unknown source)         @ scannertest.scanlines(scannertest.java:23)         @ scannertest.main(scannertest.java:6)

use multiple scanners (on same stream) bad practice, because scanners consume stream share.

this cause of exception java.util.nosuchelementexception: no line found had.

i've tested code , exception raised second nextline() invocation.

into each scanner class saved reference same input stream.

when scanner1.nextline() method invoked, read bunch of bytes on stream , position moved ahead.

just clear, i've double checked debugging source code of scanner class.

when nextline() method called, behind scenes stream moved ahead of 1024 position copying result buffer

// internal buffer used hold input private charbuffer buf;

try debug java source code , @ method readinput().


Comments

Post a Comment

Popular posts from this blog

Command prompt result in label. Python 2.7 -

i want put result(output) of shell command label. command works, label shows "0", however, in command prompt, result shown correctly, need showed in label. doing ubuntu. myg1 = button(root, text="rodyti informacija", command=lambda: gauti()) myg1.pack(side=bottom) def gauti(): imti = tekstas.get("1.0", "end-1c") info = subprocess.call("id '{imti}' ".format(imti=imti), shell=true) w = label(root, text= info) w.pack(side = bottom) subprocess.call() returns exit code of process created (in case 0 success). if want text output of process, should instead call subprocess.check_output() .
Read more

javascript - How do I use URL parameters to change link href on page? -

i change href value of link using url parameters. example: default <a id="dlink" href="link-1">link</a> but, when user goes https://url.com/?dlink=link-2 it swaps out link new link <a id="dlink" href="link-2">link</a> first need value url. if you're not using javascript framework can create function using jquery. please check get url parameter jquery or how query string values in js it. after that, element "a" id , set value there. $("#dlink").attr("href", hreffromparam);
Read more

amazon web services - AWS Route53 Trying To Get Site To Resolve To www -

so have domain nameservers pointed aws route 53. site hosted on ec2 instance , reachable resolves site.com, if input www.site.com. i'm curious how site resolve www.site.com. have under route53 domains hosted zone 2 additional record sets outside of ns , soa: a site.com ec2 elastic ip cname www.site.com ec2 public dns i can reach site using both site.com , www.site.com, resolve site.com. there way make if enter either, resolves www.site.com? at first, both should record set. a site.com ec2 elastic ip www.site.com ec2 elastic ip and need redirect setting in web server (nginx, apache, ..) following. (source: how redirect www non-www nginx on centos 7 ) redirect non-www www if want redirect users plain, non-www domain www domain, add server block: server { server_name example.com; return 301 $scheme://www.example.com$request_uri; } save , exit. configures nginx redirect requests "example.com" "www.example.com". not...
Read more