On parsing a CSV file [closed]

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I have this project for the university where they're asking me to create a simple bank system in Java. So far I've been able to do well except when it comes to store data for using it next time..

Lately I've found the storing code where all of my data are stored on a text file as :

int  str     str    int
5487,Samer,Lebanon,1000000
8792,Ahmad,Lebanon,2500000

and so on using the io libraries such as :

public static void saveToFile(int[] accounts,String[] names,String[] addresses,int[] balances,int maxTmp) {
    bubbleSorting(accounts,names,addresses,balances,maxTmp);
    try {
    //What ever the file path is.
        File statText = new File("C:/Users/Wicked Angel/Desktop/customers.txt");
        FileOutputStream is = new FileOutputStream(statText);
        OutputStreamWriter osw = new OutputStreamWriter(is);    
        Writer w = new BufferedWriter(osw);
        for(int i=0;i<maxTmp;i++)
            w.write(accounts[i] + "," + names[i] + "," + addresses[i] + "," + balances[i] + System.getProperty("line.separator"));

        w.close();
    } catch (IOException e) {
        System.err.println("Problem writing to the file customers.txt");
    }
}

The difficulty is when I'm trying to import that text file and set each value to its specific array..

Any help ?

Answer 1

First, you have to read the text file line by line

// your file
File statText = new File("C:/Users/Wicked Angel/Desktop/customers.txt");
// read file using FileReader class
FileReader fr = new FileReader(statText);
BufferedReader br = new BufferedReader(fr);
// the first line is the header line and might be ignored
String line = br.readLine();
// loop through each line by reading it from the buffer
while ((line = br.readLine()) != null) {
    // process each line
}
br.close();

This will loop through each lines in your file. The line will be a string. Here below is an example of the first string in the while loop.

line: "5487,Samer,Lebanon,1000000"

What you have to do is to separate each parts and bring it to an array. This can be done with the Split() method from String-object. (click on the method name to read the documentation).

String[] myParts = line.Split(",");

The result will be then

myParts: ["5487"] ["Samer"] ["Lebanon"] ["1000000"]

That's an array. Just go through the above array and store each variable in the appropriate array. The first element in ArrayList<int> accounts, the second element in ArrayList<String> names ... Here below is an example for the first element

// outside loop 
ArrayList<int> accounts = new ArrayList<int>();

// inside loop 
accounts.Add(Integer.parseInt(myParts(0))); 
// since it should be an integer, I parse it to int before adding it

The reason behind the use of ArrayList is because you don't know how many lines you have in your text. Ofc you can check it, but performance wise, it's advisable to use a dynamic array, which is ArrayList. (Or other list objects if you want). If you want to read more about ArrayList, please refer to this documentation to create, add element, get element, ...

Oh, also don't forget to cast the first and third element to int, or you will get errors when trying to add these info in an int ArrayList. If you want, you can also validate each element to ensure that you don't have faulty data (like the result of splitting a line is an array of three elements, which is incorrect).

This should help you to solve your import problems. Good luck

Answer 2

use your ',' as the delimiter. read each line and seperate them using delimiter like, say if i wanted to extract String text="holy,molly" i would do

String holy=text.substring(0,text.indexOf(','));

and

String molly=text.substring(text.indexOf(','))