bufferedwriter - Writing to file in Java -

first things first, novice when comes java. have set myself little project , stuck. trying write file exists, overwrites it. trying replace line contains 'maxbooks'.

here code using:

filewriter writefile = new filewriter(filelocation);             bufferedreader readlines = new bufferedreader(new filereader(filelocation));             bufferedwriter writelines = new bufferedwriter(writefile);              system.out.println("\n-----file begin-----");              while((finallines = readlines.readline()) != null){                  if(finallines.contains("maxbooks")){                     writelines.newline();                     writelines.write(finallines);                      system.out.println("this if statement");                     system.out.println(finallines);                 } else {                     filelines.add(new string(finallines));                     system.out.println("this else statement");                     system.out.println(finallines);                 }             }              system.out.println("------file end------"); 

please bear in mind have left out try , catch. please let me know how can edit text file. let me know if need more info

thanks :)

edit

sorry, should clarify. trying edit 1 line in test file, not whole text file.

final code:

filewriter writefile = new filewriter(filelocation + ".tmp", true);             bufferedwriter writelines = new bufferedwriter(writefile);              bufferedreader readlines = new bufferedreader(new filereader(filelocation));               system.out.println("\n-----file begin-----");              while((finallines = readlines.readline()) != null){                  if(finallines.contains("maxbooks")){                     writelines.write("maxbooks = " + maxbooks);                     writelines.newline();                      system.out.println("this if statement");                     system.out.println(finallines);                 } else {                     filelines.add(new string(finallines));                     system.out.println("this else statement");                     writelines.write(finallines);                     writelines.newline();                 }             }              system.out.println("------file end------");              file2.renameto(file);              writelines.close(); 

you overwrite file try read, bad practice. write new file, rename original file.