Question

Need help with java programming.

Here is what I need to do:

Write a Java program that could help test programs that use text files. Your program will copy an input file to standard output, but whenever it sees a “$integer”, will replace that variable by a corresponding value in a 2^ndfile, which will be called the “variable value file”.

The requirements for the assignment:

1.     The input and variable value file are both text files that will be specified in the command line. The way to run your program will thus be:

java cs401hw1.GenTextFile input_file variable_value_file

2.     As indicated above, input_file is just a regular text file. Your code should not generate output based on the names of the files, of course.

3.     Similarly, variable_value_file is also a regular text file, but each line of the file is considered to be the value of the next variable. That is, the first line of the file is the value of $0, the 2^nd line is the value of $1, the 3^rd line is the value of $2, and so on. The value does not include the end-of-line.

a.      The java.util.Scanner class lets you easily read in the lines. Construct a File using the 2^nd command-line argument, then pass this File to the constructor for Scanner

4.     When a variable ($integer) is encountered in the input file, the corresponding line from the variable values file is displayed instead.

a.      The java.io.FileReader class has a read() method that will read one character at a time

b.     To convert the characters for integer into an actual integer value the static method Integer.parseInt(String) is helpful

5.     A variable does not have to be used, or it may be used more than once.

6.     Variable numbers are in the range of 0 to 9999.

7.     Any two variables are separated by at least one character (so $1$2 won’t be in the input)

8.     Comment each function to explain what the function does, as well as the overall program.

9.     Choose good variable and function names

10.  Name the constants you use

Example:

$0 POPULATION GROWTH

(each * represents $1 person)

$2 $3

variable value file:

Town

1

1800

*

Expected output:

Town POPULATION GROWTH

(each * represents 1 person)

1800 *

PLEASE WRITE PROGRAM CLEARLY!!!!

Answer 1

JAVA PROGRAM

package cs401hw1;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

//Class: GenTextFile
public class GenTextFile {
  
   private String inputFile; //instance variable inputFile
   private String varValFile; //instance variable varValFile
  
   //Constructor
   //Take values from input arguments and populate instance variables
   public GenTextFile(String[] args){
       if(args!=null && args.length==2){
           inputFile = args[0];
           varValFile = args[1];
       }else{ //if invalid number of arguments
           System.out.println("Invalid arguments!");
       }
   }
   public static void main(String[] args){
      
       GenTextFile gtf = new GenTextFile(args); //Create GenTextFile instance
       String currentLine = null;
      
       Scanner inFileScanner = gtf.createFileScanner(gtf.inputFile); //Create input file Scanner instance
       List<String> variables = gtf.createVariables(gtf.varValFile); //Create List of variables from varValFile
      
       if(inFileScanner!=null){
       while(inFileScanner.hasNextLine()){ //As long as there is a line in input file
           currentLine = inFileScanner.nextLine(); //read the line
           String updatedLineData = gtf.generateFinalDataForALine(currentLine, variables); //generate updted line data by replacing variables
           System.out.println(updatedLineData);//print the updated line in console
       }
         
       inFileScanner.close();//close input file scanner
       }
      
      
   }
  
   /**
   * Generate final data for currentLine by replacing variable
   * @param currentLine
   * @param variables
   * @return
   */
   private String generateFinalDataForALine(String currentLine,List<String> variables){
       StringBuilder sb = new StringBuilder();//Create Stringbuilder
       char[] lineData = currentLine.toCharArray(); //Convert the currentLine String into CharArray
  
       for(int i = 0; i < lineData.length; i++){ //Traverse through individual characters
      
           //If current Character is '$'
           //Read next consecutive characters as long as they are digit
           if(lineData[i]=='$'){
           String indexStr = "";
           char currentChar;
           int p;
           for( p = i+1; p < lineData.length; p++){ //traverse from next characters
               currentChar = lineData[p];
               if(!Character.isDigit(currentChar)){ //if it is not a digit break
                   i = p-1;
                   break;
               }
               indexStr +=currentChar; //concat digits into indexStr
           }
           int index = Integer.parseInt(indexStr); //convert indexStr into int index
           String variable = variables.get(index); //get variable from variables list at the index
           sb.append(variable); //append that variable in string builder
           if(p==lineData.length){//if the current digit is the last character of the line, breaks from outer for loop
               break;
           }
       }else{
           //otherwise add the not digit character into the stringBuilder
           sb.append(lineData[i]);
       }
   }
  
   return sb.toString();//return string from the string builder
   }
  
  
   //Create file scanner from the given filename
   private Scanner createFileScanner(String fileName){
       Scanner file = null;
       try {
           file = new Scanner(new File(fileName));
       } catch (FileNotFoundException e) {
           System.out.println("Input file:"+fileName+" is not found!");
       }
      
       return file;
   }
  
   /**
   * Create list of variables from the variable file name
   * @param varFileName
   * @return
   */
   private List<String> createVariables(String varFileName){
       Scanner varFileScanner = createFileScanner(varFileName); //create file scanner
       List<String> variables = null;
      
       if(varFileScanner!=null){
           variables = new ArrayList<String>();
           while(varFileScanner.hasNextLine()){
               variables.add(varFileScanner.nextLine());//add every line of file into the list
           }
           varFileScanner.close();//close var file scanner
       }
      
       return variables;
      
   }
}

=====================================

THE FILES USED

=====================================

InputFile.txt

$0 POPULATION GROWTH
(each * represents $1 person)
$2 $3

VariableFile.txt

Town
1
1800
*

=========================================

OUTPUT

=========================================

First set the input arguments to the program from eclipse Run Configurations.

Run Configurations Create, manage, and run configurations Run a Java application J B X Name: GenTextFile Main (= Arguments JRE - Classpath Program arguments: InputFile.txt VariableFile.txt Source Environment” ra Application GenTextFile Library Matrix MultiplicaitonThrea Std DevGUI TestStudent Variables... VM arguments: nit Plug-in Test aven Build de.js Application Gi Framework sk Context Test Variables... Working directory: Default: ${workspace_loc:August} Revert Apply Filter matched 23 of 23 ite Run Close

The output obtained after the program ran is below:

A Problems @ Javadoc Console X <terminated > GenTextFile [Java Application) C:\Program FilesVava\jre 1.8.0_121\bin\javaw.exe (24-Aug-2019, 8:58:21 AM) Town POPULATION GROWTH (each * represents 1 person) 1800 *