Develop Reference

Is there a way to modify my code to reset all integers and strings when the code starts running [duplicate]

I got an run time exception in my program while I am reading a file through a Scanner.
java.util.NoSuchElementException: No line found
at java.util.Scanner.nextLine(Unknown Source)
at Day1.ReadFile.read(ReadFile.java:49)
at Day1.ParseTree.main(ParseTree.java:17)
My code is:
while((str=sc.nextLine())!=null){
i=0;
if(str.equals("Locations"))
{
size=4;
t=3;
str=sc.nextLine();
str=sc.nextLine();
}
if(str.equals("Professions"))
{
size=3;
t=2;
str=sc.nextLine();
str=sc.nextLine();
}
if(str.equals("Individuals"))
{
size=4;
t=4;
str=sc.nextLine();
str=sc.nextLine();
}
int j=0;
String loc[]=new String[size];
while(j<size){
beg=0;
end=str.indexOf(',');
if(end!=-1){
tmp=str.substring(beg, end);
beg=end+2;
}
if(end==-1)
{
tmp=str.substring(beg);
}
if(beg<str.length())
str=str.substring(beg);
loc[i]=tmp;
i++;
if(i==size ){
if(t==3)
{
location.add(loc);
}
if(t==2)
{
profession.add(loc);
}
if(t==4)
{
individual.add(loc);
}
i=0;
}
j++;
System.out.print("\n");
}

with Scanner you need to check if there is a next line with hasNextLine()
so the loop becomes
while(sc.hasNextLine()){
str=sc.nextLine();
//...
}
it's readers that return null on EOF
ofcourse in this piece of code this is dependent on whether the input is properly formatted

I also encounter with that problem.
In my case the problem was that i closed the scanner inside one of the funcs..
public class Main
{
public static void main(String[] args)
{
Scanner menu = new Scanner(System.in);
boolean exit = new Boolean(false);
while(!exit){
String choose = menu.nextLine();
Part1 t=new Part1()
t.start();
System.out.println("Noooooo Come back!!!"+choose);
}
menu.close();
}
}
public class Part1 extends Thread
{
public void run()
{
Scanner s = new Scanner(System.in);
String st = s.nextLine();
System.out.print("bllaaaaaaa\n"+st);
s.close();
}
}
The code above made the same exaption, the solution was to close the scanner only once at the main.

You're calling nextLine() and it's throwing an exception when there's no line, exactly as the javadoc describes. It will never return null
https://docs.oracle.com/javase/8/docs/api/java/util/Scanner.html

For whatever reason, the Scanner class also issues this same exception if it encounters special characters it cannot read. Beyond using the hasNextLine() method before each call to nextLine(), make sure the correct encoding is passed to the Scanner constructor, e.g.:
Scanner scanner = new Scanner(new FileInputStream(filePath), "UTF-8");

Your real problem is that you are calling "sc.nextLine()" MORE TIMES than the number of lines.
For example, if you have only TEN input lines, then you can ONLY call "sc.nextLine()" TEN times.
Every time you call "sc.nextLine()", one input line will be consumed. If you call "sc.nextLine()" MORE TIMES than the number of lines, you will have an exception called
"java.util.NoSuchElementException: No line found".
If you have to call "sc.nextLine()" n times, then you have to have at least n lines.
Try to change your code to match the number of times you call "sc.nextLine()" with the number of lines, and I guarantee that your problem will be solved.

Need to use top comment but also pay attention to nextLine(). To eliminate this error only call
sc.nextLine()
Once from inside your while loop
while (sc.hasNextLine()) {sc.nextLine()...}
You are using while to look ahead only 1 line. Then using sc.nextLine() to read 2 lines ahead of the single line you asked the while loop to look ahead.
Also change the multiple IF statements to IF, ELSE to avoid reading more than one line also.

I ran into this problem, my structure was:
1 - System
2 - Registration <-> 3 - validate
I was closing Scanner on each of the 3 steps. I started to close the Scanner only in system and it solved.

How are multiple sentences printed in Java using Scanner?

I want to print multiple sentences (each having more than one word) in Java but I am getting a run time error even after using .nextLine(). Below is my code, could someone point out what am I doing wrong?
import java.util.*;
class GFG
{
public static void main (String[] args)
{
Scanner sc = new Scanner(System.in);
int t = sc.nextInt(); //t>1
for(int p=1; p<=t; p++)
{
sc.nextLine();
String s = sc.nextLine();
System.out.println(s);
}
}
} // Input-
// 2
// HOW ARE YOU
// GOD IS ONE
// Output-
// HOW ARE YOU -(followed by run time error)

The first line in the for-loop: sc.nextLine() reads a line from the in stream and discards it (the return value is not placed into any variable). In your code, you read two lines in every iteration (4 for the provided input) while there are only 2 lines of input. Therefore you need to remove this line (the first sc.nextLine()).
As a side note, when I tried to run the program it just waited for more lines and did not throw a runtime error (also in case you encountered one it's better to post the exception itself).

Output error: Exception in thread "main" java.util.NoSuchElementException: No line found [duplicate]

I got an run time exception in my program while I am reading a file through a Scanner.
java.util.NoSuchElementException: No line found
at java.util.Scanner.nextLine(Unknown Source)
at Day1.ReadFile.read(ReadFile.java:49)
at Day1.ParseTree.main(ParseTree.java:17)
My code is:
while((str=sc.nextLine())!=null){
i=0;
if(str.equals("Locations"))
{
size=4;
t=3;
str=sc.nextLine();
str=sc.nextLine();
}
if(str.equals("Professions"))
{
size=3;
t=2;
str=sc.nextLine();
str=sc.nextLine();
}
if(str.equals("Individuals"))
{
size=4;
t=4;
str=sc.nextLine();
str=sc.nextLine();
}
int j=0;
String loc[]=new String[size];
while(j<size){
beg=0;
end=str.indexOf(',');
if(end!=-1){
tmp=str.substring(beg, end);
beg=end+2;
}
if(end==-1)
{
tmp=str.substring(beg);
}
if(beg<str.length())
str=str.substring(beg);
loc[i]=tmp;
i++;
if(i==size ){
if(t==3)
{
location.add(loc);
}
if(t==2)
{
profession.add(loc);
}
if(t==4)
{
individual.add(loc);
}
i=0;
}
j++;
System.out.print("\n");
}

with Scanner you need to check if there is a next line with hasNextLine()
so the loop becomes
while(sc.hasNextLine()){
str=sc.nextLine();
//...
}
it's readers that return null on EOF
ofcourse in this piece of code this is dependent on whether the input is properly formatted

I also encounter with that problem.
In my case the problem was that i closed the scanner inside one of the funcs..
public class Main
{
public static void main(String[] args)
{
Scanner menu = new Scanner(System.in);
boolean exit = new Boolean(false);
while(!exit){
String choose = menu.nextLine();
Part1 t=new Part1()
t.start();
System.out.println("Noooooo Come back!!!"+choose);
}
menu.close();
}
}
public class Part1 extends Thread
{
public void run()
{
Scanner s = new Scanner(System.in);
String st = s.nextLine();
System.out.print("bllaaaaaaa\n"+st);
s.close();
}
}
The code above made the same exaption, the solution was to close the scanner only once at the main.

You're calling nextLine() and it's throwing an exception when there's no line, exactly as the javadoc describes. It will never return null
https://docs.oracle.com/javase/8/docs/api/java/util/Scanner.html

For whatever reason, the Scanner class also issues this same exception if it encounters special characters it cannot read. Beyond using the hasNextLine() method before each call to nextLine(), make sure the correct encoding is passed to the Scanner constructor, e.g.:
Scanner scanner = new Scanner(new FileInputStream(filePath), "UTF-8");

Your real problem is that you are calling "sc.nextLine()" MORE TIMES than the number of lines.
For example, if you have only TEN input lines, then you can ONLY call "sc.nextLine()" TEN times.
Every time you call "sc.nextLine()", one input line will be consumed. If you call "sc.nextLine()" MORE TIMES than the number of lines, you will have an exception called
"java.util.NoSuchElementException: No line found".
If you have to call "sc.nextLine()" n times, then you have to have at least n lines.
Try to change your code to match the number of times you call "sc.nextLine()" with the number of lines, and I guarantee that your problem will be solved.

Need to use top comment but also pay attention to nextLine(). To eliminate this error only call
sc.nextLine()
Once from inside your while loop
while (sc.hasNextLine()) {sc.nextLine()...}
You are using while to look ahead only 1 line. Then using sc.nextLine() to read 2 lines ahead of the single line you asked the while loop to look ahead.
Also change the multiple IF statements to IF, ELSE to avoid reading more than one line also.

I ran into this problem, my structure was:
1 - System
2 - Registration <-> 3 - validate
I was closing Scanner on each of the 3 steps. I started to close the Scanner only in system and it solved.

Scanner nextLine, stuck in while loop or exiting at odd times

I started doing the CodeAbbey problems last night, they mentioned using stdIn since some the input data is long so copy/paste is much easier than by hand. I had never used the Scanner before so it looked easy enough. I got it working for single line inputs then I got a problem where the input was:
867955 303061
977729 180367
844485 843725
393481 604154
399571 278744
723807 596408
142116 475355
I assumed that nextLine would read each couple, xxxx yyyyy. I put the code in a while loop based on if nextLine is not empty. It runs, but I get weird output, and only after I hit return a few times.
package com.secryption;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
System.out.println("Input: ");
Scanner scanner = new Scanner(System.in);
String input = "";
while(!(scanner.nextLine().isEmpty())) {
input = input + scanner.nextLine();
}
String[] resultSet = input.split("\\s+");
for(String s : resultSet) {
System.out.println(s);
}
}
}
I thought I might need something after adding scanner.nextLine() to input. I tried a space and that didn't help. I tried a newline and that didn't make it better.
This "should" put all the numbers in a single array, nothing special. What am I missing with scanner?
EDIT: Ok so #Luiggi Mendoza is right. I found this How to terminate Scanner when input is complete? post. So basically it it working, I just expected it to do something.

The problem is here:
while(!(scanner.nextLine().isEmpty())) {
input = input + scanner.nextLine();
}
Scanner#nextLine reads the line and will continue reading. You're reading two lines and not storing the result of the first line read, just reading and storing the results of the second.
Just change the code above to:
StringBuilder sb = new StringBuilder();
while(scanner.hasNextLine()) {
sb.append(scanner.nextLine()).append(" ");
}

hasNext() is an end of file indicator that terminates by combining keys control d on Mac ox and control z on windows pressing enter won't send the right message
to JVM

while (scanner.hasNext()) loop not working twice? Java

I have made a program which is like a vending machine!
My code is similar to:
public static void main (String [] args) {
Scanner sc = new Scanner (System.in);
while(sc.hasNext()) {
String string = sc.next();
sum = generateSum(sum)
.....
}
}
public static int generateSum(int sum) {
Scanner sc = new Scanner (System.in);
while (sc.hasNext()) {
....
}
return sum;
}
Sorry for simplifying my code, but the normal one is very long! However, the problem is that I use while (sc.hasNext()) loop twice. Basically I want to continue my main method until the input from the user is TERMINATE, but my program terminates after running once.
I figured that if I take out my generateSum method, then the loop in my main method works fine so i guess it has to be something to do with have the while (sc.hasNext()) loop twice.
Any ideas how I can fix the problem?

The hasNext() method is going to block until you hit the end of file marker on System.in because it doesn't know if there's more input until it reads a full buffers worth or hits end of file (which you can signal with Control-Z on windows and Control-D on unix). At that point System.in is at the EOF mark and there's no way to re-open it from your code.
If you need to process multiple streams of data from System.in you are going to have to use some sort of sentinel value (such as the word END) to mark the end of one input stream and the beginning of another.

I'm quite sure that if you consume the input being scanned with sc.next() the state changes and hasNext() returns accordingly.The problem may be there.

The hasNext() method can be called as much as you want. But if in the inner loop you are calling the next() method, then that can eat the values from your outer loop.
So the inner loop most probably breaks after hasNext() is false and thus the outer loop also finishes.