How to add data to an existing file and also read it with Java -

this simple program user inputs 2 variable values , chooses operator. program displays results , asks user if save file. format should x + y = z. declared variable should catch user input

    resw = ""; 

i unable resw capture user input variable values can saved file. if enter

    resw = "x + y = z"; 

then saved. second problem...when saves writes on previous save. need save each entry new line. don't know how that.

finally, view file well. far can tell need filereader , bufferedreader so. not working though , moves on next line of code.

if (answer.equals("y")||answer.equals("y")){     system.out.println(resw);     bufferedwriter.write(resw);     bufferedwriter.newline();     system.out.println("results saved file.");    } system.out.println("do want review results y/n"); answer = ins.nextline();  if (answer.equals("y")||answer.equals("y")){     filereader filereader = new filereader(filename);     bufferedreader bufferedreader = new bufferedreader(filereader); } 

just use printwriter, , printwriter.println, , sure close file

if (answer.equals("y")||answer.equals("y")) {     system.out.println(resw);     printwriter.println(resw);     printwriter.close();