1 Primitives

Question 1

How does java know if a decimal value is a float or a double?

Answer 1

Java uses double by default. If not specified, the value will be a double.
Otherwise it knows by what is added at the end
100.123f, 100.123F
100.123d, 100.123D

Question 2

What is the range of a byte?

Answer 2

-128 to 127

Question 3

What is the range of a short?

Answer 3

-32,768 and a maximum value of 32,767 (inclusive).

Question 4

How many times do static initializers run?

Answer 4

Only ONCE!

Question 5

How many times do instance initializers run? Instance, not static.

Answer 5

Every time a new object is made

Question 6

Is a reference variable required when calling a constructor?
Is this legal?    new MyClass();

Answer 6

Reference is NOT required. If the constructor is called without one, the functions inside will be performed you just can’t refer to that object.

new MyClass();   // LEGAL, no reference
MyClass thing1 = new MyClass(); // example with a reference

Question 7

Should long be written with capital or lowercase L?

Answer 7

Capital 123L

Question 8

should double and float be written with capital or lowercase?

Answer 8

lowercase, but either is legal.

123.0d, 123.0f

Question 9

How can the number of code blocks be determined?

Answer 9

Count the number of pairs of curly braces.

Question 10

What is the resulting data type after arithmetic between any of the data types byte - through - int?

Answer 10

The result is an int (ex, byte + byte = int). Add a cast to the operation if you need to assign the result back to the smaller data type.