Core Java - Interview Questions and Answers for 'File' | Search Interview Question

Core Java - Interview Questions and Answers for 'File' - 52 question(s) found - Order By Newest

Q1. What will be the output of following code ?

public static void main(String[] args){
String name = null;
File file = new File("/folder", name);
System.out.print(file.exists());
}

Core Java

Ans. NullPointerException

at line: "File file = new File("/folder", name);"

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code file handling}

Q2. What is a stream and what are the types of Streams and classes of the Streams?

Core Java

Ans. A Stream is an abstraction that either produces or consumes information. There are two types of Streams :

Byte Streams: Provide a convenient means for handling input and output of bytes.

Character Streams: Provide a convenient means for handling input & output of characters.

Byte Streams classes: Are defined by using two abstract classes, namely InputStream and OutputStream.

Character Streams classes: Are defined by using two abstract classes, namely Reader and Writer.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java file io streams byte stream character stream file handling Asked in 3 Companies}

Q3. What will be the output of following code ?

public static void main(String[] args){
String parent = null;
File file = new File(parent, "myfile.txt");
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}

Core Java

Ans. It will create the file myfile.txt in the current directory.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code file handling}

Q4. Which of the following file is called deployment descriptor ?

a. application.xml
b. project.xml
c. web.xml
d. build.xml

Java EE

Ans. web.xml

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve configuration files deployment server java}

Q5. Will this code compile fine ?

ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream(new File("newFile.txt")));

Core Java

Ans. Yes.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code objectoutputstream fileoutputstream yesno file handling}

Q6. What are the configuration files in Hibernate ?

Hibernate

Ans. hibernate.cfg.xml ( Main Configuration File )

and *.hbm.xml files ( Mapping Files )

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve hibernate configuration mapping files}

Q7. Name few File IO related classes and interfaces ?

Core Java

Ans. http://www.buggybread.com/2015/01/java-file-io-classes-and-interfaces.html

Sample Code for File

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io input output file io file handling}

Q8. Given two files with list of words, write a program to show the common words in both files

Core Java

Ans. import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.io.*;
public class Common {
public static void main(String ar[])throws Exception
   {
      File f=new File("a.txt");
File f1=new File("x.java");
      System.out.println(f.exists());
FileInputStream fin = new FileInputStream(f);
      FileInputStream fin1 = new FileInputStream(f1);

      byte b[]=new byte[10000];
byte b1[]=new byte[10000];
fin.read(b);
fin1.read(b1);
String s1 = new String(b);
String s2 =new String(b1);

String words1[] = s1.trim().split(" ");
String words2[] = s2.trim().split(" ");
Listlist1 = new ArrayList<>(Arrays.asList(words1));
Listlist2 = new ArrayList<>(Arrays.asList(words2));
list1.retainAll(list2);
System.out.println(list1);
}
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve file handling file io code coding Asked in 1 Companies}

Q9. What are the ways in which an application can maintain config variables ?

Ans. 1. Property files
2. config xml
3. Database

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve config property files}

Q10. Write code to create a folder if it doesn't exist.

Core Java

Ans. File folder = new File(path);

if(!folder.exists()){
try {
folder.mkdir();

} catch (Exception e) {}
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve code coding file handling basic}

Q11. Tell something about BufferedWriter ? What are flush() and close() used for ?

Ans. BufferedWriter is temporary source for data storage.BufferedWriter is used to write character data to the file.Flush() is method available in B.W which ensures that all data items are written to file including last character.Close() is used to closes the character output stream.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java java io input output file handling file io output stream bufferedwriter flush close}

Q12. What is Scanner class used for ? when was it introduced in Java ?

Core Java

Ans. Scanner class introduced in Java 1.5 for reading Data Stream from the imput device. Previously we used to write code to read a input using DataInputStream. After reading the stream , we can convert into respective data type using in.next() as String ,in.nextInt() as integer, in.nextDouble() as Double etc

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java java5 scanner file io file input data input stream file handling basic}

Q13. What is Spring configuration file?

Spring

Ans. Spring configuration file is an XML file. This file contains the classes information and describes how these classes are configured and introduced to each other.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve j2ee spring mvc frameworks web applications spring configuration file Asked in 1 Companies}

Q14. What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?

Core Java

Ans. The Reader/Writer class hierarchy is character-oriented, and the InputStream/OutputStream class hierarchy is byte-oriented

Sample Code for InputStream

Sample Code for OutputStream

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java file io streams reader class writer class inputstream outputstream stream file handling}

Q15. What is the purpose of the System class?

Core Java

Ans. The purpose of the System class is to provide access to system resources.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java system io file io}

Q16. Which of the following is a canonical path ?

1. C:\directory\..\directory\file.txt
2. C:\directory\subDirectory1\directory\file.txt
3. \directory\file.txt

Ans. 2nd

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio}

Q17. What will the following code print when executed on Windows ?

public static void main(String[] args){
String parent = null;
File file = new File("/file.txt");
System.out.println(file.getPath());
System.out.println(file.getAbsolutePath());
try {
System.out.println(file.getCanonicalPath());
} catch (IOException e) {
e.printStackTrace();
}
}

Core Java

Ans. file.txtC:file.txtC:file.txt

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code file handling}

Q18. What will be the output of following code ?

public static void main(String[] args){
String child = null;
File file = new File("/folder", child);
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}

Core Java

Ans. NullPointerException at line:File file = new File("/folder", child);

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code file handling}

Q19. What will be the output of following code, assuming that currently we are in c:Project ?

public static void main(String[] args){
String child = null;
File file = new File("../file.txt");
System.out.println(file.getPath());
System.out.println(file.getAbsolutePath());
try {
System.out.println(file.getCanonicalPath());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

Core Java

Ans. ..file.txt
C:WorkspaceProject..file.txt
C:Workspacefile.txt

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code file handling}

Q20. Which is the abstract parent class of FileWriter ?

Core Java

Ans. OutputStreamWriter

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio filewriter outputstreamwriter file handling}

Q21. Which class is used to read streams of characters from a file?

Core Java

Ans. FileReader

Sample Code for FileReader

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio filereader file handling}

Q22. Which class is used to read streams of raw bytes from a file?

Core Java

Ans. FileInputStream

Sample Code for FileInputStream

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio fileinputstream file handling}

Q23. Which is the Parent class of FileInputStream ?

Core Java

Ans. InputStream

Sample Code for InputStream

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio fileinputstream inputstream file handling}

Q24. Which of the following code is correct ?

a.

FileWriter fileWriter = new FileWriter("../file.txt");
File file = new File(fileWriter );
BufferedWriter bufferedOutputWriter = new BufferedWriter(fileWriter);

b.

BufferedWriter bufferedOutputWriter = new BufferedWriter("../file.txt");
File file = new File(bufferedOutputWriter );
FileWriter fileWriter = new FileWriter(file);

c.

File file = new File("../file.txt");
FileWriter fileWriter = new FileWriter(file);
BufferedWriter bufferedOutputWriter = new BufferedWriter(fileWriter);

d.

File file = new File("../file.txt");
BufferedWriter bufferedOutputWriter = new BufferedWriter(file);
FileWriter fileWriter = new FileWriter(bufferedOutputWriter );

Core Java

Ans. c.

File file = new File("../file.txt");
FileWriter fileWriter = new FileWriter(file);
BufferedWriter bufferedOutputWriter = new BufferedWriter(fileWriter);

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code filewriter bufferedwriter scjp ocjp file handling}

Q25. Which exception should be handled in the following code ?

File file = new File("../file.txt");
FileWriter fileWriter = new FileWriter(file);

Core Java

Ans. IOException

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code exception ioexception file handling}

Q26. Which exceptions should be handled with the following code ?

FileOutputStream fileOutputStream = new FileOutputStream(new File("newFile.txt"));

Ans. FileNotFoundException

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code scjp ocjp filenotfoundexception fileoutputstream file handling}

Q27. What is the problem with this code ?

class BuggyBread1 {

private BuggyBread2 buggybread2;

public static void main(String[] args){
try {
BuggyBread1 buggybread1 = new BuggyBread1();
ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream(new File("newFile.txt")));
objectOutputStream.writeObject(buggybread1);
} catch (Exception e) {
e.printStackTrace();
}
}
}

Core Java

Ans. Though we are trying to serialize BuggyBread1 object but we haven't declared the class to implement Serializable.

This will throw java.io.NotSerializableException upon execution.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code serialization notserializableexception exception file handling}

Q28. Will this code run fine if BuggyBread2 doesn't implement Serializable interface ?

class BuggyBread1 implements Serializable{
private BuggyBread2 buggybread2 = new BuggyBread2();

public static void main(String[] args){
try {
BuggyBread1 buggybread1 = new BuggyBread1();
ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream(new File("newFile.txt")));
objectOutputStream.writeObject(buggybread1);
} catch (Exception e) {
e.printStackTrace();
}
}
}

Core Java

Ans. No, It will throw java.io.NotSerializableException.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code serialization notserializableexception exception file handling}

Q29. Will this code work fine if BuggyBread2 doesn't implement Serializable ?

class BuggyBread1 extends BuggyBread2 implements Serializable{
private int x = 5;

public static void main(String[] args){
try {
BuggyBread1 buggybread1 = new BuggyBread1();
ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream(new File("newFile.txt")));
objectOutputStream.writeObject(buggybread1);
} catch (Exception e) {
e.printStackTrace();
}
}
}

Core Java

Ans. Yes.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio coding code serialization yesno file handling}

Q30. What is asynchronous I/O ?

Ans. It is a form of Input Output processing that permits other processing to continue before the I/O transmission has finished.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java io file fileio java7 architecture}

Search Interview Questions

Help us and Others Improve. Please let us know the questions asked in any of your previous interview.