Advanced Java

1. What is a transient variable?
   A transient variable is a variable that may not be serialized.
2. Which containers use a border Layout as their default layout?
   The Window, Frame and Dialog classes use a border layout as their default layout.
3. Why do threads block on I/O?
   Threads block on I/O (that is enters the waiting state) so that other threads may execute while the I/O Operation is performed.
   

Solving linear equations in integers

Oranges can be packed in sets of 10 oranges in box type A or 25 oranges in box type B. A carton comprising of 1000 oranges of type a and b is packed. How many different combinations are possible in the number of type A and type B boxes while organizing the oranges?

a. 21	b. 20
c. 19	d. 18

Finding integers solutions is one of the important question that is being asked in the recent exams. We will discuss some interesting methodologies to solve them.
If a system of equations has two variables, we need atleast two equations to solve them.  But what if, we are given only one equation?
Suppose taking my date of birth, my date is multiplied by 31 and month is multiplied by 12 and given the product as 494.  Can you determine my birth date and month?
Take an equation ax+by=k. 
This is in the format of A+B=k. As k is constant, If A increases, B should decrease.  The question is, by how much?  Simple. If "A" reduces by "b" (the coefficient of y), B should increase by "a" (the coefficient of x) and vice versa.
For example, 5x + 3y = 100. One solution for this equation is (20, 0). Now the next solution is (23, -5), (26, - 10) .... or (17, 5), (14, 10), ..... '