How to store something in text file?

Question

Hello
I have question and i do not know how to do this.
can any one explain for me how i can save something in a text file.
i create calculator,and there is one question i need to do it:((Store the record of the session in a text file. ))
what i need to write some codes and so on.
please can u give idea ?

Answer 1

Alena,
Here's my static FileUtilz class, which includes a writeFile method, and several other handy methods.
package krc.io;
import java.util.Collection;
import java.util.List;
import java.util.ArrayList;
import java.io.File;
import java.io.FileReader;
import java.io.BufferedReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.io.InputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.FileNotFoundException;
import java.util.Arrays;
public abstract class FileUtilz
    public static final int bfrSize = 4096;
    public static void writeFile(String content, String filename)
    throws IOException
        PrintWriter out = null;
        try {
            out = new PrintWriter(new FileWriter(filename));
            out.write(content);
        } finally {
            //try {if(out!=null)out.close();}catch(Exception ignore){}
            out.close();
    public static String readFile(String filename)
    throws IOException, FileNotFoundException
        FileReader in = null;
        StringBuffer out = new StringBuffer();
        try {
            in = new FileReader(filename);
            char[] cbuf = new char[bfrSize];
            int n = in.read(cbuf, 0, bfrSize);
            while(n > 0) {
                out.append(cbuf);
                n = in.read(cbuf, 0, bfrSize);
        } finally {
            //try {if(in!=null)in.close();}catch(Exception ignore){}
            in.close();
        return out.toString();
    public  static String[] readFileIntoArray(String filename)
    throws IOException, FileNotFoundException
        return readFileIntoList(filename).toArray(new String[0]);
    public  static List<String> readFileIntoList(String filename)
    throws IOException, FileNotFoundException
        BufferedReader in = null;
        List<String> out = new ArrayList<String>();
        try {
            in = new BufferedReader(new FileReader(filename));
            String line = null;
            while ( (line = in.readLine()) != null ) {
                out.add(line);
        } finally {
            try {if(in!=null)in.close();}catch(Exception e){}
        return out;
    public static byte[] readBytes(String filename)
    throws IOException, FileNotFoundException
      //start = System.currentTimeMillis();
      File file = new File(filename);
      byte[] out = new byte[(int)file.length()];
      InputStream in = new FileInputStream(file);
      int size = in.read(out);
      in.close();
      //System.out.println("readBytes("+filename+"="+size") took "+(System.currentTimeMillis()-start));
      return out;
    public static boolean isSameFile(String filenameA, String filenameB)
    throws IOException, FileNotFoundException
      File fileA = new File(filenameA);
      File fileB = new File(filenameB);
      //check for same physical file
      if( fileA.equals(fileB) ) return(true);
      //compare sizes
      if( fileA.length() != fileB.length() ) return(false);
      //compare contents (buffer by buffer)
      boolean same=true;
      InputStream inA = null;
      InputStream inB = null;
      try {
        inA = new FileInputStream(fileA);
        inB = new FileInputStream(fileB);
        byte[] bfrA = new byte[bfrSize];
        byte[] bfrB = new byte[bfrSize];
        int sizeA=0, sizeB=0;
        do {
          sizeA = inA.read(bfrA);
          sizeB = inA.read(bfrB);
          if ( sizeA != sizeB ) {
            same=false;
          } else if ( sizeA == 0 ) {
            //do nothing
          } else if ( !Arrays.equals(bfrA,bfrB) ) {
            same=false;
        } while (same && sizeA != -1);
      } finally {
        if(inA!=null)inA.close();
        if(inB!=null)inB.close();
      return(same);
    public static String basename(String path, boolean cutExtension)
        String fname = (new File(path)).getName();
        if (cutExtension) {
            int i = fname.lastIndexOf(".");
            if (i > 0) {
                fname = fname.substring(0,i);
        return fname;
    public static String dirname(String path)
        return (new File(path)).getParent();
}