java - Why is there no output when I run my code? -

i trying read file called ecoli.txt, contains dna sequence ecoli, , store contents string. tried print string test code. however, when run program, there no output. still new java sure there error in code, need finding it.

package codons; import java.io.*; public class codons  {      public static void main(string[] args)      {         try          {             filereader codons = new filereader("codons.txt");             filereader filereader = new filereader("ecoli.txt");             bufferedreader ecoli = new bufferedreader(filereader);             stringbuilder dna_string = new stringbuilder();             string line = ecoli.readline();             while(line != null);             {                 dna_string.append(line);                 line = ecoli.readline();             }             string string = new string(dna_string);             system.out.println(string);             ecoli.close();         }          catch (filenotfoundexception e)          {             e.printstacktrace();         }          catch (ioexception e)          {             e.printstacktrace();         }       }  } 

edit:

i still having trouble getting program work way wanted attempted complete writing rest of wanted in program , still not getting output. anyway, @ now:

package codons; import java.io.*; import java.util.*; import java.lang.*; import java.text.*; public class codons  {     public static void main(string[] args)      {         try          {             filereader filecodons = new filereader("codons.txt");             filereader filereader = new filereader("ecoli.txt");             bufferedreader ecoli = new bufferedreader(filereader);             stringbuilder dna_sb = new stringbuilder();             string line = ecoli.readline();             while(line != null)             {                 dna_sb.append(line);                 line = ecoli.readline();             }             string dna_string = new string(dna_sb);             ecoli.close();             bufferedreader codons = new bufferedreader(filecodons);             stringbuilder codon_sb = new stringbuilder();             string codon = codons.readline();             while(codon != null)             {                 codon_sb.append(codon);                 line = codons.readline();             }             string codon_string = new string(codon_sb);             codons.close();             for(int x = 0; x <= codon_sb.length(); x++)             {                 int count = 0;                 string codon_ss = new string(codon_string.substring(x, x+3));                 for(int = 0; <= dna_sb.length(); i++)                 {                     string dna_ss = new string(dna_string.substring(i, i+3));                     int result = codon_ss.compareto(dna_ss);                     if(result == 0)                     {                         count += 1;                     }                 }                 system.out.print("the codon '");                 system.out.print(codon_ss);                 system.out.print("'is in dna sequence");                 system.out.print(count);                 system.out.println("times.");             }         }          catch (filenotfoundexception e)          {             e.printstacktrace();         }          catch (ioexception e)          {             e.printstacktrace();         }       }  } 

remove ; after while(line != null), causes infinite loop instead of executing next instructions.

the reason explained here: effect of semicolon after 'for' loop (the question c language, equivalent in java).