File I/O - Quiz

Create a File object that represents the path stored in the variable path

Open a byte stream to read from an existing file represented by the File object file

Create a Path instance from a relative string path stored in fileName using the NIO API

When using java.io.File, which method checks if the File instance refers to a directory?

Which stream pair is most appropriate for copying a binary image file?

What is a key advantage of wrapping a FileReader in a BufferedReader?

Which PrintWriter method allows you to produce formatted output similar to printf in C?

To read integers from a text file using Scanner, which constructor is most appropriate?

Which interface must a class implement to allow its instances to be serialized using ObjectOutputStream?

Which NIO type represents a location of a file or directory in a file system?

Which Files method checks if a file exists at a given Path without throwing an exception?

Which FileChannel feature allows you to map a region of a file directly into memory for fast access?

Which statement about ObjectInputStream deserialization is correct?

Order the steps to read all lines from a text file using BufferedReader and print them

Drag and drop to reorder, or use the arrows.

Order the steps to serialize an object to a file using ObjectOutputStream

Drag and drop to reorder, or use the arrows.

What is the output of this code related to the File class?

1import java.io.File;
2
3public class Test {
4    public static void main(String[] args) {
5        File f = new File("notes.txt");
6        System.out.println(f.getName());
7    }
8}

What is the output when reading characters with FileReader?

1import java.io.*;
2
3public class Test {
4    public static void main(String[] args) throws Exception {
5        char[] data = {'J', 'a', 'v', 'a'};
6        System.out.println(data[1]);
7    }
8}

What does this Scanner-based code print?

1import java.util.*;
2
3public class Test {
4    public static void main(String[] args) {
5        String text = "42 true";
6        Scanner sc = new Scanner(text);
7        int n = sc.nextInt();
8        boolean b = sc.nextBoolean();
9        System.out.println(n + "-" + b);
10        sc.close();
11    }
12}

What is the output when using Paths and Files?

1import java.nio.file.*;
2import java.io.*;
3
4public class Test {
5    public static void main(String[] args) throws Exception {
6        Path p = Paths.get("example.txt");
7        System.out.println(p.getFileName());
8    }
9}

What is the output when positioning a ByteBuffer?

1import java.nio.*;
2
3public class Test {
4    public static void main(String[] args) {
5        ByteBuffer buffer = ByteBuffer.allocate(4);
6        buffer.put((byte)10);
7        buffer.put((byte)20);
8        buffer.flip();
9        buffer.get();
10        System.out.println(buffer.get());
11    }
12}

Find the bug related to closing resources in this file copy code

Click on the line(s) that contain the bug.

import java.io.*;

public class Copier {

    public void copy(String src, String dest) throws IOException {

        FileInputStream in = new FileInputStream(src);

        FileOutputStream out = new FileOutputStream(dest);

        byte[] buffer = new byte[1024];

        int bytesRead;

        while ((bytesRead = in.read(buffer)) != -1) {

            out.write(buffer, 0, bytesRead);

        }

    }

}

Find the bug in this deserialization code that reads a Person object

Click on the line(s) that contain the bug.

import java.io.*;

public class Loader {

    public Person load(String fileName) throws IOException, ClassNotFoundException {

        FileInputStream fis = new FileInputStream(fileName);

        ObjectInputStream ois = new ObjectInputStream(fis);

        Object obj = ois.readObject();

        ois.close();

        fis.close();

        return (Person) fis; // cast and return

    }

}

Match each I/O class with what it is best suited for

Click an item on the left, then click its match on the right. Click a matched item to unmatch.

Match NIO concepts with their primary purpose

Click an item on the left, then click its match on the right. Click a matched item to unmatch.

Complete the code to write text to a file using PrintWriter and then read it line by line with BufferedReader

Complete the code to safely serialize an object to a file using ObjectOutputStream

Complete the code to create a Path and check if it exists using the NIO Files API

Complete the code to read an int from the console using Scanner and print it

Click the line that may cause an IOException when working with a FileInputStream

Click on the line to select.

import java.io.*;

public class ReaderDemo {

    public static void main(String[] args) throws Exception {

        FileInputStream fis = new FileInputStream("missing.txt");

        int data = fis.read();

        System.out.println(data);

        fis.close();

    }

}

Click the line where a NullPointerException would occur when using a File object

Click on the line to select.

import java.io.*;

public class FileNullDemo {

    public static void main(String[] args) {

        File f = null;

        System.out.println(f.getAbsolutePath());

    }

}