Java program to replace multiple words in a file

Change multiple words in a file using Java






Contents of script.txt file

MYWORLD 543x_family COM1
ERASE_RACE
TR_PASSWORD
//BOSE
TP_DATA_LOCK test.txt
LMN 5C00 1010 982B
Change the words COM1 to COM5 and test.txt to mytext.txt.






import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;


public class ReplaceWords
{

            private static StringBuffer myStrArray = new StringBuffer();
            //Stringbuffer can be used to append strings
            private static String newStrArray[] = new String[6];//used to hold the strings

         
            public static void main(String[] args)
            {
                        readFile();
            }

            private static void readFile()
            {
                        String next;
                        int i = 0;

                        FileInputStream fstream = null;
                        try
                        {
                                    fstream = new FileInputStream("script.txt");
                        }
                        catch (FileNotFoundException ex)
                        {
                                    System.out.println("FileNotfound:-" + ex);
                        }
                       
                        // Get the object of DataInputStream
                        DataInputStream in = new DataInputStream(fstream);
                        BufferedReader br = new BufferedReader(new InputStreamReader(in));
                        String strLine, oldtext = null;
                        String newtext = null;
                        try
                        {
                                    //Read File Line By Line
                                    while ((strLine = br.readLine()) != null)
                                    {
                                                oldtext += strLine + "\r\n";

                                                //Tokenizes the current line read with space delimiter
                                                StringTokenizer tz = new StringTokenizer(strLine, " ");
                                                while (tz.hasMoreTokens())
                                                {
                                                            next = tz.nextToken();
                                                            //if  word contains the text 'COM',COM5 is appended instead of 'COM1'
                                                            if (next.contains("COM"))
                                                            {
                                                                        myStrArray.append("COM5 "); 
                                                                        //appends COM5 instead of COM1
                                                            }
                                                            //appends space is space is encountered
                                                            else if (next.contains(" "))
                                                            {
                                                                        myStrArray.append(" ");
                                                            }
                                                            //if  word contains the text '.txt',mytext.txt is appended instead of test.txt
                                                            else if (next.contains(".txt"))
                                                            {
                                                                        myStrArray.append("mytext.txt ");
                                                            }
                                                            else
                                                            {
                                                                        myStrArray.append(next + " ");
                                                            }
                                                }

                                                newtext = myStrArray.toString();
                                                newStrArray[i] = newtext;
                                                i ++;
                                                myStrArray = null;
                                                myStrArray = new StringBuffer();
                                                oldtext = null;
                                    }
                                    in.close();
                                    writeToFile();
                        }
                        catch (IOException ex)
                        {
                                    System.out.println("IO Exception:-" + ex);
                        }
            }

            //Writes string to file
            private static void writeToFile()
            {
                        FileWriter writer = null;
                        try
                        {
                                    writer = new FileWriter("script.txt");
                                    //Iterates through the string buffer
                                    for (int j = 0; j < newStrArray.length; j ++)
                                    {
                                                String strData = newStrArray[j];                                               
                                                writer.write(strData); 
                                                //writes new line to file after every line
                                                writer.write("\r\n");
                                    }
                                    writer.close();
                        }
                        catch (IOException ex)
                        {
                                    System.out.println("IOException in writeToFile:-"+ex);
                        }
                        finally
                        {
                                    try
                                    {
                                                writer.close();
                                    }
                                    catch (IOException ex)
                                    {
                                                System.out.println("Exception in closing writer:-"+ex);
                                    }
                        }
            }
}




Script.txt file will output the following

MYWORLD 543x_family COM5
ERASE_RACE
TR_PASSWORD
//BOSE
TP_DATA_LOCK mytext.txt
LMN 5C00 1010 982B