从文本文件读取

Question

I need to read data from a text file using Java and currently I am using:

public void read()  throws Exception 
{
    FileInputStream in = null;
    try 
    {
        Scanner input = new Scanner("dataset.txt");
        File inputFile = new File(fileName.nextLine());
        in = new FileInputStream(inputFile);
    } 
    catch ( Exception e) 
    {
        System.out.println(e);
    }
}

However, I wish to give the user a choice to read from dataset.txt and data.txt so I tried doing:

public void read(int name)  throws Exception 
{
    FileInputStream in = null;
    try 
    {
        File inpu = new File(name.nextLine());
        in = new FileInputStream(input);
    } 
    catch ( Exception e) 
    {
        System.out.println(e);
    }

but I am getting an error : int cannot be dereferenced

Answer 1

fileName has type int . You cannot call methods from primitive types.

Answer 2

Since you only have two different file, why don't you use an if statement to see which file the user wants to open and then give that file to your inputFile which you can pass to in .

if (fileName == 1) {
    inputFile = new File("dataset.txt");
} else if (fileName == 2) {
    inputFile = new File("data.txt");
}

Answer 3

If "name" input variable is the value selected by the user is required to use a condition to select the according file name depending on the user decission

Example:

public void read(int name)  throws Exception {
    FileInputStream in = null;
    try  {

        // File selection depending on user number selection
        String fileName="dataSet.txt";
        if(name == 2){
            fileName ="otherFileName.txt";
        }

        // InputStream creation
        File input = new File(fileName);
        in = new FileInputStream(input);

       // Your read operations here

    } catch ( Exception e) {
        System.out.println(e);
    }
}

On this example if the user press 2 the "otherFileName.txt" is used. Otherwise "dataSet.txt" is used.

Also al files are without path. These means that are required to be in the startup path of the application.

Answer 4

First your code have a lot of errors. I suppose if you are displaying this line on console

System.out.print("Please choose a dataset (1) dataset.txt , (2)data.txt : ");

User's input is in int and you are passing like fileName.nextLine() , Which cause an error

try this:

Scanner scan=new Scanner(System.in));
fileName="";
System.out.print("Please choose a dataset (1) dataset.txt , (2)data.txt : ");
int input = scan.nextInt();
if(input==1){
   fileName="dataset.txt";
}
if(input==2){
   fileName="data.txt";
}
File inputFile=new File(fileName));
... .