Top Java I/O Interview Questions.

In this post we will look at Java I/O interview questions. Examples are provided with explanation.


Q: What is Java I/O ?
A: Java I/O (Input and Output) is used to process the input and produce the output. Java makes use of the stream concepts to make I/O operation fast. The java.io package contains all the classes required for input and output operations.

Q: What is difference between Scanner and BufferedReader?
A: Scanner is used for parsing tokens from the contents of the stream while BufferedReader just reads the stream and does not do any special parsing. Usually we pass a BufferedReader to a scanner as the source of characters to parse.

Q: How to process java.io.InputStream object and produce a String?
A:

static String convertStreamToString(java.io.InputStream iStream)
 {
    java.util.Scanner scanInput = new java.util.Scanner(iStream).useDelimiter("\\A");
    return scanInput.hasNext() ? scanInput.next() : "";
 }

Q: How to create a Java String from the contents of a file??
A:

				
static String readFile(String path, Charset encoding) 
  throws IOException 
{
  byte[] encoded = Files.readAllBytes(Paths.get(path));
  return new String(encoded, encoding);
}

Q: What are the uses of FileInputStream and FileOutputStream in java?
A: java.io.FileInputStream and java.io.FileOutputStream were introduced in JDK 1.0. These APIs are used to read and write stream input and output. They can also be used to read and write images.

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