Thread: PrintStream, strings and reading from a file.

I've gotten sort of stuck on my assignment for my Java class and I was wondering if anyone could point me in the right direction.

The general idea of what is intended is that the computer will read an exterior file, and every time it stops at something like < noun > it will ask the reader basically "please input a: noun", so I first want it to find the instance of a < word > and read it, and then I want to be able to change that word to what the user inputted by creating a new file of this new story.

So the original file would read 'Fred Meyers is < adjective >
The console would say Please input a: adjective
The user would input a word (let's say smart)
And a new file would get the words as they're printed, so it would be Fred Meyers is smart in the new file.

import java.util.*;
import java.io.*;
public class StoryGenerator {
	public static void main(String[] args) {
		readFile();
	}
 
	public static void readFile() {
		double sum = 0.0;
		try {	
			System.out.println("Enter the name of your story file:");
			Scanner scan = new Scanner(System.in);
			Scanner file = new Scanner(new File(scan.next()));
			while (file.hasNext()) {
			String input = file.next();
			if (input.startsWith("<") && input.endsWith(">")) {
					String word = input.substring(1, input.length() - 1);
					System.out.println("Please input a: " + word);
				}
			}
		}
		catch (java.io.FileNotFoundException ex) {
			System.out.println("File not found.");
			System.exit(-1);
		}
	}
 
}

So I figured out how to print the < noun > thing (and edited the above code), for all except the word with the space (i.e. <your name> ), So I need help figuring out how to get the <your name> to show up, I am also stuck on how to replace it and write a new document (Although I think that I am supposed to reassign the string in the if loop to the new word, and there should probably be PrintStream somewhere.)

EDIT:

Okay, I got "your name" to show up by using a nested if loop.

import java.util.*;
import java.io.*;
public class StoryGenerator {
	public static void main(String[] args) {
		readFile();
	}
 
	public static void readFile() {
		double sum = 0.0;
		try {	
			System.out.println("Enter the name of your story file:");
			Scanner scan = new Scanner(System.in);
			Scanner file = new Scanner(new File(scan.next()));
			while (file.hasNext()) {
			String input = file.next();
			if (input.startsWith("<") && input.endsWith(">")) {
					String word = input.substring(1, input.length() - 1);
					System.out.println("Please input a: " + word);
				}
			if (input.startsWith("<your")) {
				String word = input.substring(1, input.length());
				System.out.print("Please input a: " + word);
				input = file.next();
 
				if (input.startsWith("name>")) {
					word = input.substring(0, input.length() - 1);
					System.out.println(" " + word);
				}
			}
			}
		}
		catch (java.io.FileNotFoundException ex) {
			System.out.println("File not found.");
			System.exit(-1);
		}
	}
}

Now I need help figuring out how to replace that input and then print the story out to a new file (as stated above.)

EDIT: Figured out how to replace the input, now I just need to know how to PrintStream as the story goes on.

current code:

import java.util.*;
import java.io.*;
public class StoryGenerator {
	public static void main(String[] args) {
		readFile();
	}
 
	public static void readFile() {
		double sum = 0.0;
		try {	
			System.out.println("Enter the name of your story file:");
			Scanner scan = new Scanner(System.in);
			Scanner file = new Scanner(new File(scan.next()));
			while (file.hasNext()) {
			String input = file.next();
			if (input.startsWith("<") && input.endsWith(">")) {
					String word = input.substring(1, input.length() - 1);
					System.out.println("Please input a: " + word);
					input.replaceAll(input, scan.next());
				}
			if (input.startsWith("<your")) {
				String word = input.substring(1, input.length());
				System.out.print("Please input a: " + word);
				input = file.next();
				input.replaceAll(input, "");
 
				if (input.startsWith("name>")) {
					word = input.substring(0, input.length() - 1);
					System.out.println(" " + word);
					input.replaceAll(input, scan.next());
				}
 
			}
			}
		}
		catch (java.io.FileNotFoundException ex) {
			System.out.println("File not found.");
			System.exit(-1);
		}
	}
}

Unfortunately, FileWriter is not something I've learned and I have any idea how to implement to the above code, likewise the file we have to use to bring the story has to be declared early on (when they scan for the file name).

I tried using a FileWriter, more as an experiment, and I have this:

import java.util.*;
import java.io.*;
public class StoryGen {
	public static void main(String[] args) throws IOException {
			Scanner scan = new Scanner(System.in);
			Scanner file = new Scanner(new File(scan.next()));
			FileWriter f = new FileWriter(new File("outfile.txt"));
			while (file.hasNext()) {
				String input = file.next();
				if (input.startsWith("<") && input.endsWith(">")) {
						String word = input.substring(1, input.length() - 1);
						System.out.println("Please input a: " + word);
						input.replaceAll(input, scan.next());
				}
				if (input.startsWith("<your")) {
					String word = input.substring(1, input.length());
					System.out.print("Please input a: " + word);
					input = file.next();
					input.replaceAll(input, "");
					if (input.startsWith("name>")) {
						word = input.substring(0, input.length() - 1);
						System.out.println(" " + word);
						input.replaceAll(input, scan.next());
					}
				}
			}
			f.close();
	}
}

Unfortunately, outfile is blank when I open it. Help?

Doesn't f.close() near the end of the code do the flush/closing of the FileWriter? It still only creates a blank document instead of writing the text.

So I did realize that I wasn't printing anything out to the filewriter, and I renamed it like above so that my code is now this:

import java.util.*;
import java.io.*;
public class StoryGenB {
	public static void main(String[] args) throws IOException {
			try {
			Scanner scan = new Scanner(System.in);
			Scanner file = new Scanner(new File(scan.next()));
			FileWriter filewriter = new FileWriter(new File("outfile.txt"));
			while (file.hasNext()) {
				String input = file.next();
				if (input.startsWith("<") && input.endsWith(">")) {
						String word = input.substring(1, input.length() - 1);
						System.out.println("Please input a: " + word);
						word = input.replace(input, scan.next());
						filewriter.write(word);
				}
				if (input.startsWith("<your")) {
					String word = input.substring(1, input.length());
					System.out.print("Please input a: " + word);
					input = file.next();
					input.replaceAll(input, "");
					if (input.startsWith("name>")) {
						word = input.substring(0, input.length() - 1);
						System.out.println(" " + word);
						word = input.replace(input, scan.next());
						filewriter.write(word);
					}
				}
				else { filewriter.write(input);}
				filewriter.write(" ");
 
			}
			filewriter.close();
		}
	catch (java.io.FileNotFoundException ex) {  
		System.out.println("File not found.");  
		System.exit(-1);  
        }  
 
	}
 
}

Now, my new problem is that the words that are taken care of in the first if loop (the ones starting and ending with <> are being printed first replaced, then printing out the <word> as well.

Once there was a chick<gender> named Sam . [He/She] was a wizard! One day, an owl came with a letter. It said, "Please come to Kalamazoo<city> and learn magic. You will need to bring kitten<noun> , puppy<noun> and a car<noun> . You may also bring one pet. Your ticket for the <the city again> Express <mode of transport> is enclosed!" Sam went to Stiches<store> and bought a red<colour> giraffe<animal> and named it Clore<name> . Once the shopping was done, Sam was ready for Magic School! [He/She] hopped on the <the mode of transport again> and never looked back!

So for all the words in the first if statement, it is printing that word and the replaced word.

So I fixed that so the current code is this:

import java.util.*;
import java.io.*;
public class StoryGenB {
	public static void main(String[] args) {
		file();
	}
 
	public static void file() {
			try {
			Scanner scan = new Scanner(System.in);
			Scanner file = new Scanner(new File(scan.next()));
			FileWriter filewriter = new FileWriter(new File("outfile.txt"));
			while (file.hasNext()) {
				String input = file.next();
				if (input.startsWith("<") && input.endsWith(">")) {
						String word = input.substring(1, input.length() - 1);
						System.out.println("Please input a: " + word);
						word = scan.next();
						filewriter.write(word);
						input = file.next();
						filewriter.write(" ");
				}
				if (input.startsWith("<")) {
					String word = input.substring(1, input.length());
					System.out.print("Please input a: " + word);
					input = file.next();
					input.replace(input, "");
					if (input.endsWith(">")) {
						word = input.substring(0, input.length() - 1);
						System.out.println(" " + word);
						word = scan.next();
						filewriter.write(word);
					}
				}
				else { filewriter.write(input);}
				filewriter.write(" ");
 
			}
			filewriter.close();
		}
	catch (java.io.FileNotFoundException ex) {  
		System.out.println("File not found.");  
		System.exit(-1);  
        }  
        catch (java.io.IOException ex) {
        	System.out.println("File not created");
        	System.exit(-1);
 
	}
	}
 
}

I found that <your name> isn't the only one with spaces that I need to replace, so now I'm trying to figure out a way to make it so that it will keep going if the string has a "<" until it finds a ">" Any suggestions?

So I have this:

import java.util.*;
import java.io.*;
public class StoryGenB {
	public static void main(String[] args) {
		file();
	}
 
	public static void file() {
			try {
			Scanner scan = new Scanner(System.in);
			Scanner file = new Scanner(new File(scan.next()));
			FileWriter filewriter = new FileWriter(new File("outfile.txt"));
			while (file.hasNext()) {
				String input = file.next();
				if (input.startsWith("<")) {
					int start = input.indexOf("<");
					int end = input.indexOf(">");
					String word = input.substring(start +1, end);
					System.out.println("Please input a: " + word);
					word = scan.next();
				}
				else {filewriter.write(input);}
				filewriter.write(" ");
 
			}
			filewriter.close();
		}
	catch (java.io.FileNotFoundException ex) {  
		System.out.println("File not found.");  
		System.exit(-1);  
        }  
        catch (java.io.IOException ex) {
        	System.out.println("File not created");
        	System.exit(-1);
 
	}
	}
 
}

The index is supposed to find the start ("<") and the next index is supposed to find the end (">"), however I am unsure how to make it keep looking to find the end, as when the above code is compiled it gives a string index out of range error.

Here is the error message I am getting:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String ind
ex out of range: -1
        at java.lang.String.substring(String.java:1911)
        at StoryGenF.file(StoryGenF.java:17)
        at StoryGenF.main(StoryGenF.java:5)