Elements of Java Language - Continued

Core Java Training
Elements of Java programming

Classification: Restricted
Agenda
• Elements of Java programming language
• Conditional Statements
• Loops

Conditional Statements
• if
• if-else
• if-else ladder
• switch-case
• Ternary operator

If statement

if and if-else examples

if-else ladder

Ternary Operator

Switch…case statement
Unlike if-then and if-then-else statements, the switch statement can have a number
of possible execution paths. A switch works with the byte, short, char, and int
primitive data types. It also works with enumerated types (discussed in Enum Types),
the String class, and a few special classes that wrap certain primitive types: Character,
Byte, Short, and Integer (discussed in Numbers and Strings).
* Provide default value – it is a good practice.
* The break is important. Don’t forget it.

Exercise
Use Math.random() and an if-else statement to print the results of a coin flip.

Exercise
• Write two programs - one using switch case and another using if else ladder
to print the full name of a month provided that the user inputs an integer
between 1 to 12.
• E.g. if the user inputs 1, print January.

Loops
• while
• do..while
• for

while

do-while

Exercise – what is output?

Exercise – what is the output?

Difference between while and do-while?
Do-while loop is always executed at least once, as the condition is checked at
the end of the loop.

for statement

Loop Examples

Branching Statements: Break, Continue and Return…
Break:
The break statement has two forms: labeled and unlabeled. You saw the
unlabeled form in the previous discussion of the switch statement. You can
also use an unlabeled break to terminate a for, while, or do-while loop
An unlabeled break statement terminates the innermost switch, for, while, or
do-while statement, but a labeled break terminates an outer statement.

Break statement: Example (Without Label)

Break statement: Example (With Label)

Continue:
The continue statement skips the current iteration of a for, while , or do-
while loop.
The unlabeled form skips to the end of the innermost loop's body and
evaluates the boolean expression that controls the loop.
The following program, ContinueDemo , steps through a String, counting the
occurences of the letter "p". If the current character is not a p, the continue
statement skips the rest of the loop and proceeds to the next character. If it
is a "p", the program increments the letter count.

Continue Statement: Example (Without Label)

Return:
The last of the branching statements is the return statement. The return statement
exits from the current method, and control flow returns to where the method was
invoked. The return statement has two forms: one that returns a value, and one that
doesn't. To return a value, simply put the value (or an expression that calculates the
value) after the return keyword.
return ++count;
The data type of the returned value must match the type of the method's declared
return value. When a method is declared void, use the form of return that doesn't
return a value.
return;

Exercise: What is the output?

Exercise
Consider the following code snippet.
if (aNumber >= 0)
if (aNumber == 0)
System.out.println("first string");
else System.out.println("second string");
System.out.println("third string");
• What output do you think the code will produce if aNumber is 3?
• Write a test program containing the previous code snippet; make aNumber 3. What
is the output of the program? Is it what you predicted? Explain why the output is
what it is; in other words, what is the control flow for the code snippet?
• Using only spaces and line breaks, reformat the code snippet to make the control
flow easier to understand.
• Use braces, { and }, to further clarify the code.

Exercise
• Print 10 HelloWorld using different kinds of loops

Exercise
• Write a program to print all powers of 2 less than or equal to n.

Exercise
Write a program to print the binary equivalent of a decimal integer input by
the user.

Exercise
Use conditional operator (ternary operator) to find the least of 3 numbers
input by the user.

Exercise: What is the value of m and n?

Exercise: What’s wrong with this?

Exercise: What is the output?
Answer: a*b

Topics to be covered in next session
• Autoboxing and Unboxing in Java
• Handling Arrays

Thank You!

Elements of Java Language - Continued

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