Thread: Creating a File with eclipse:

import java.io.*; 
 
public class ReadNumbers
{
void input()
{
	String File_name = "num.txt";
	File numbers = new File(File_name);
 
	if(numbers.exists()){System.out.println("The file was found");} 
	else {System.out.println("The file was not found!!!");}
}
	public static void main(String[] args) 
	{
		ReadNumbers read = new ReadNumbers();
 
		read.input();
	}
 
}

I am using eclipse and I went to file, add new file and named it num.txt:shot.png like show in the picture.

However it cannot find it. What am I doing wrong?

void input()
{
	String File_name = "num.txt";
	File numbers = new File(File_name);
 
	if(numbers.exists()){System.out.println("The file was found");} 
	else
	{
		final Formatter make_file;
		try{make_file = new Formatter(File_name);} 
 
		catch(Exception e)
		{ 
		System.out.println("File was not found but we created one for you.");
		}
 
	}
}

This works I just have to figure out where it is making the file and more importantly, how to read the files input.

import java.io.*; 
import java.util.*;
//import java.lang.*;
 
public class ReadNumbers
{
private Formatter make_file;
private String File_name = "num.txt";
 
void input()
{
	File numbers = new File(File_name);
 
	if(numbers.exists()){System.out.println("The file was found");} 
	else
	{
		try{make_file = new Formatter(File_name);} 
 
		catch(Exception e){ System.out.println("You have an error.");}	
	}
}
void WriteFile()
{
	try
	{
		FileOutputStream f = new FileOutputStream(File_name);
 
		for(int i=0;i<10;i++)
		{
			f.write(i);
		}
		f.close();
	}
	catch(IOException e)
	{
		System.out.println("There was an error");
	}
 
}
 
 
	public static void main(String[] args) 
	{
		ReadNumbers read = new ReadNumbers();
 
		read.input();
		read.WriteFile();
	}
 
}

This is my first project messing with files in Java as you might be able to tell. However now that I can run this program there is nothing written to it. It just deletes whatever I had in the file previously.

--- Update ---

void WriteFile()
{
	try
	{
		FileOutputStream f = new FileOutputStream(File_name);
		String name = "Write this to the file...";
 
		byte b[] = name.getBytes();
 
		for(int i=0;i<b.length;i++)
		{
			f.write(b[i]);
		}
		f.close();
	}
	catch(IOException e)
	{
		System.out.println("There was an error");
	}
 
}

Now I got a string to work but not the integers that I posted above?

This is what is bugging me here and I thinking I am over thinking it. I am trying to find a way similar to C++ to input and output file. For example

 
ifstream in("num.txt",ios::in);
int a=0,b=0;
 
while(in>>a>>b)
{
std::cout<<a<<""<<b<<"\n";
}

Something along those line. For lets say I know the structure of the file. It seems way more complicated in Java, am I correct?

When I used the char array in the second example I had output to the file, but not with the first example.

void ReadFile() throws Exception 
{
	FileReader file = new FileReader(File_name);
	BufferedReader reader = new BufferedReader(file);
 
	String text ="";
	String line = reader.readLine();
 
	while(line != null)
	{
		text += line;
		line = reader.readLine();
	}
	System.out.println(text);
 
	reader.close();
}

How is this? Is there a better way? What if I had values like (1 8 name 45) and I knew that was the files format. What is a good approach to that?

Thank you very much... I will continue will work on this program. I am comfortable with and decided to learn Java.
Thanks for the help, I am sure I will be back soon for more questions. Hopefully I can contribute to this site more when I am better.

void ReadFile() throws Exception 
{
	FileReader file = new FileReader(File_name);
	BufferedReader reader = new BufferedReader(file);
 
	String text ="";
	String line = reader.readLine();
 
	while(line != null)
	{
		text += line; //text is assigned the string value that was in the buffer
		line = reader.readLine();//reads next line
	}
	System.out.println(text);//once end of file was reached the String is printed
 
	reader.close();
}

I am reading Java the complete Reference Eighth Edition and it is rather frustrating how many ways there are to handle files. The above example seems to be pretty simple, is this the most common way? What is your favorite and why?

Lets say I wanted to break down the input because I new the file format, is DataInputStream the simplest and efficient way to handle that? I know you already told me about one way to handle this but since there were some many ways to handle files I figured there was something designed for such a thing.

try(DataInputStream din=new DataInputStream(new FileInputStream("num.txt")))
{
int age = read.readInt();
String DOB = read.readString();
String name = read.readString();
 
//down here I could make a list of nodes with the above data and push in the information to use it later
}
catch(FileNotFoundException e)
{
System.out.println("File was not found");
return;
}

Which leads me to my next question:

 
struct foo
{
int age;
std::String DOB;
std::String Name;
}MyFoo
 
std::list<MyFoo>Mylist;  //here I could call push after I got all the data from the file like I explained above
int main()
{
//some stuff
}

What is a good way to handle this in Java? Java doesn't have structs but it does have inner classes. Is that what I need here?