Answer Posted / kuldeep sharma

Java is Platform Independent language it uses Virtual
System (JVM) in an existing operating system to run
programs.
The JVM itself is not Platform independent it is platform
dependent. but its functionality is same for all verison of
JVM for different OSs.

The Source Code of a Java Program is compiled to avail the
advantages of compiler like fast development, i mean all
the errors are checked and displayed by the compiler at once
(in 99.99% cases) to make the code error free.

An error free Java Code is converted into BYTECODE ;
directly understood by the JVM(for all OSs).

Now consider we compiled a.java >> a.class on linux, the
a.class is portable and runnable on other OS like Windows
because class files are fun by JVM but not by the OSs that
why we can say
Java is platform Independent.

How many bytes is a string in java?

1038

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How to call one constructor from the other constructor ?

1118

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What methodology can be employed to locate substrings inside a string?

998

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What is difference between calling start() and run() method of thread?

1210

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Explain wait() method of object class ?

1291

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Is 0 true or is 1 true?

1004

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What are the types of casting?

1118

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Can interface be private in java?

1068

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What is the generic function?

1041

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List some important features of java 10 release?

1161

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Is java owned by oracle?

1073

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What happens if an exception is throws from an object's constructor?

1177

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Can we override private method in java?

1142

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The following program reads data (details of students) from a file named students.txt and converts it into e-mail addresses. The results are written to a file named studentemail.txt. students.txt consists of a number of lines, each containing the data of a student in colon delimited format: Last Name:First Name:Student Number Each input record is converted to an e-mail address and written to studentemail.txt in the following format: the first character of the last name + the first character of the first name + the last four digits of the student number + “@myunisa.ac.za” import java.io.*; public class EmailConverter { public static void main(String[] args) throws IOException { BufferedReader input = new BufferedReader(new FileReader ("students.txt")); PrintWriter output = new PrintWriter(new FileWriter ("studentemail.txt")); String line = input.readLine(); while (line != null) { // Extract the information for each student String[] items = line.split(":"); // Generate the email address String email = "" + items[0].charAt(0) + items[1].charAt(0) + items[2].substring(4,8) + "@myunisa.ac.za"; email = email.toLowerCase(); // Output output.println(email); line = input.readLine(); } input.close(); output.close(); } } Rewrite the class so that it handles possible errors that may occur. In particular, it should do the following: • It should catch at least three appropriate exceptions that might occur, and display suitable messages. • At this stage, the program will not run correctly if there is an empty line in the input file. Change the program so that if an empty line is encountered, an exception is thrown and the empty line is ignored. This exception should be handled with the display of a suitable error message. • Before the e-mail address is added to the output file, check if the student number has 8 digits. If not, throw an InvalidFormatException (which the program should not handle itself)

1995

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What are the concepts of 'OOPS'?

1115

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