JAVA, comparing two strings -

[edited} ok it, let me reformulate. numvol 45 , contents of file is

54;a;23;c;de;56 23;d;24;c;h;456 45;87;c;y;535 432;42;h;h;543 

but still can't fix problem, return 543. im trying return line when equals numvol check first number of line.

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i'm having trouble comparing 2 strings. let's have .csv file following content: 54;a;b;c;de , numvol value 54. method should returning 54 reason doesnt enter in "if" , return "de".

public static string test(int numvol)throws exception{     file file = new file("test.csv");     scanner scanner = new scanner(file);     scanner.usedelimiter(";");     string line = "";     string snumvol = ""+numvol; //create string numvol value in     while (scanner.hasnext()){         line = scanner.next();         if(line.equals(snumvol)){             scanner.close();             return line;         }     }     scanner.close();     return line; } 

the problem you've told scanner use ; delimiter, it's not using whitespace delimiter anymore. token being tested against "45" isn't "45", it's "456\n45" (the end of previous line, newline, , beginning of next line), isn't match.

change usedelimiter line use both semicolons , whitespace delimiters:

scanner.usedelimiter("[;\\s]"); 

...and scanner sees "456" , "45" separately, , matches "45".

this code:

import java.util.*; import java.io.*;  public class parse {     public static final void main(string[] args) {         try {             string result = test(45);             system.out.println("result = " + result);         }         catch (exception e) {             system.out.println("exception");         }     }      public static string test(int numvol)throws exception{         file file = new file("test.csv");         scanner scanner = new scanner(file);         scanner.usedelimiter("[;\\s]"); // <==== change here         string line = "";         string snumvol = ""+numvol;         while (scanner.hasnext()){             line = scanner.next();             if(line.equals(snumvol)){                 scanner.close();                 return line;             }         }         scanner.close();         return line;     } } 

with test.csv:

54;a;23;c;de;56 23;d;24;c;h;456 45;87;c;y;535 432;42;h;h;543

shows this:

$ java parse result = 45

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the way find answer problem walk through code debugger , watch value of line, or (if reason don't have debugger?!), insert system.out.println("line = " + line); statement loop see being compared. instance, if insert system.out.println("line = " + line); above line = scanner.next(); line above , use ";" delimiter:

import java.util.*; import java.io.*;  public class parse {     public static final void main(string[] args) {         try {             string result = test(45);             system.out.println("result = " + result);         }         catch (exception e) {             system.out.println("exception");         }     }      public static string test(int numvol)throws exception{         file file = new file("test.csv");         scanner scanner = new scanner(file);         scanner.usedelimiter(";"); // <== using ";"         string line = "";         string snumvol = ""+numvol;         while (scanner.hasnext()){             line = scanner.next();             system.out.println("line = [[" + line + "]]");             if(line.equals(snumvol)){                 scanner.close();                 return line;             }         }         scanner.close();         return line;     } } 

you see this:

$ java parse line = [[54]] line = [[a]] line = [[23]] line = [[c]] line = [[de]] line = [[56 23]] line = [[d]] line = [[24]] line = [[c]] line = [[h]] line = [[456 45]] line = [[87]] line = [[c]] line = [[y]] line = [[535 432]] line = [[42]] line = [[h]] line = [[h]] line = [[543 ]] result = 543

...which helps visualize problem.