Answer / dasharath

basically we use marker interface to make special type of object.
If we take an example of a book shop where we find different type of books, in that suppose you want to display all the books which are related to Java then you can use marker interface there.
You can create a Interface say JavaBooks which wont be having any methods(A blank interface), then all the classes(say for example I say MyJavaBook) implements this blank Interface.
And then while displaying all the books related to Java you can chk using instancOf whether the book is of type JavaBooks(Marker Interface which we created previously).

write a program that inputs two real numbers then exchanges their values.

7 Answers   Infosys,

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For printing a message we use System.out.println in normal programs. We use String msg="text....."; Can't we use String msg=" " in normal programs and System.out.println("........") in applets. Please answer this question?

0 Answers  

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does anyone know the code to display a triangle using a applet?

1 Answers  

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Financial: credit card number validation) Credit card numbers follow certain patterns. A credit card number must have between 13 and 16 digits. It must start with: ■ 4 for Visa cards ■ 5 for Master cards ■ 37 for American Express cards ■ 6 for Discover cards In 1954, Hans Luhn of IBM proposed an algorithm for validating credit card numbers. The algorithm is useful to determine whether a card number is entered correctly or whether a credit card is scanned correctly by a scanner. All credit card numbers are generated following this validity check, commonly known as the Luhn check or the Mod 10 check, which can be described as follows (for illustration, consider the card number 4388576018402626): 1. Double every second digit from right to left. If doubling of a digit results in a two-digit number, add up the two digits to get a single-digit number. 2 * 2 = 4 2 * 2 = 4 4 * 2 = 8 1 * 2 = 2 6 * 2 = 12 (1 + 2 = 3) 5 * 2 = 10 (1 + 0 = 1) 8 * 2 = 16 (1 + 6 = 7) 4 * 2 = 8 2. Now add all single-digit numbers from Step 1. 4 + 4 + 8 + 2 + 3 + 1 + 7 + 8 = 37 3. Add all digits in the odd places from right to left in the card number. 6 + 6 + 0 + 8 + 0 + 7 + 8 + 3 = 38 4. Sum the results from Step 2 and Step 3. 37 + 38 = 75 5. If the result from Step 4 is divisible by 10, the card number is valid; otherwise, it is invalid. For example, the number 4388576018402626 is invalid, but the number 4388576018410707 is valid. Write a program that prompts the user to enter a credit card number as a long integer. Display whether the number is valid or invalid. Design your program to use the following methods: /** Return true if the card number is valid */ public static boolean isValid(long number) /** Get the result from Step 2 */ public static int sumOfDoubleEvenPlace(long number) /** Return this number if it is a single digit, otherwise, return * the sum of the two digits */ public static int getDigit(int number) /** Return sum of odd place digits in number */ public static int sumOfOddPlace(long number) /** Return true if the digit d is a prefix for number */ public static boolean prefixMatched(long number, int d) /** Return the number of digits in d */ public static int getSize(long d) /** Return the first k number of digits from number. If the * number of digits in number is less than k, return

0 Answers  

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How to create Date method to set the date in Ms Access

0 Answers  

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Program to print map of India in java.

2 Answers  

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we compile any program bu c:/>javac prog.java and run as c:/>java prog Here what's the meaning of c in javac. We have java Interpreter but not compiler.Then why we have to use javac. Please answer this question?

2 Answers  

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write a program that will ask the user to enter a number n and display the product of all numbers from 1 to n.

1 Answers  

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Write a program to convert a decimal number to binary form?

1 Answers   Oracle,

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Why the program getting error if we don't use String args[] in main(), even in the case of not getting any arguments from command line?

1 Answers  

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how to store and retrive a set of values without using an array

8 Answers   FCS, HCL, Maximus,

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how to create a (*)pyramid using java codes???

5 Answers   Infosys,

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