1. Control Statements:

2. Control Structures (Cont.)
Java has three kinds of control structures
Sequence statement,
Selection statements (three types) and
Repetition statements (three types)

3. if Single-Selection Statement
if statements
Execute an action if the specified condition is true
Example:
if (grade >=50)
System.out.println(“pass”);

4. if…else Double-Selection Statement
if…else statement
Executes one action if the specified condition is true or a different action if the specified condition is false
Example:
if (grade >=50)
System.out.println(“Pass”);
else
System.out.println(“Failed”);

5. if…else Double-Selection Statement (Cont.)
Nested if…else statements
if…else statements can be put inside other if…else statements
Example:
if (grade >=90)
System.out.println(“A”);
else
if (grade >=80)
System.out.println(“B”);
if (grade >=70)
System.out.println(“C”);
if (grade >=60)
System.out.println(“D”);
System.out.println(“F”);

6. Common Programming Error
Using the value of a local variable before it is initialized results in a compilation error. All local variables must be initialized before their values are used in expressions.

7. Compound Assignment Operators

8. Increment and Decrement Operators
Unary increment and decrement operators
Increment operator (++) adds one to its operand
Decrement operator (--) subtracts one from its operand
Prefix increment (and decrement) operator
Changes the value of its operand, then uses the new value of the operand in the expression
Postfix increment (and decrement) operator
Uses the current value of its operand in the expression in which the operation appears, then changes the value of the operand

9. Fig. 4.15 | Increment and decrement operators.

10. public class Increment{
public static void main( String args[] )
int c;
c=5;
System.out.println( c );
System.out.println( c++ );
System.out.println( ++c ); }

11. Counter-Controlled Repetition
Counter-controlled repetition requires:
a counter variable to count the number of times a loop is iterated
Initial value of the control variable
Increment/decrement of control variable through each loop
Loop-continuation condition that tests for the final value of the control variable

12. while statement
Repeats an action while its loop-continuation condition remains true

15. Fig. 5.3 | for statement header components.

16. for Repetition Statement (Cont.)
for ( initialization; loopContinuationCondition; increment ) statement;
can usually be rewritten as:
initialization; while ( loopContinuationCondition )
{ statement; increment; }

17. Common Programming Error
When a for statement’s control variable is declared in the initialization section of the for’s header, using the control variable after the for’s body is a compilation error.

18. Examples Using the for Statement
Vary control variable from 1 to 100 in increments of 1
for ( int i = 1; i <= 100; i++ )
Vary control variable from 100 to 1 in increments of –1
for ( int i = 100; i >= 1; i-- )
Vary control variable from 7 to 77 in increments of 7
for ( int i = 7; i <= 77; i += 7 )
Vary control variable from 20 to 2 in decrements of 2
for ( int i = 20; i >= 2; i -= 2 )
Vary control variable over the sequence: 2, 5, 8, 11, 14, 17, 20
for ( int i = 2; i <= 20; i += 3 )

20. do…while Repetition Statement
do…while structure
Similar to while structure
Tests loop-continuation after performing body of loop
i.e., loop body always executes at least once

22. Good Programming Practice
Always include braces in a do...while statement, even if they are not necessary. This helps eliminate ambiguity between the while statement and a do...while statement containing only one statement.

23. Sentinel-Controlled Repetition
int grade, total;
total=0;
System.out.print( "Enter grade or -1 to quit: " );
grade = input.nextInt();
while ( grade != -1 ) {
total = total + grade; }

24. Good Programming Practice
In a sentinel-controlled loop, the prompts requesting data entry should explicitly remind the user of the sentinel value.

25. break and continue Statements
break statement
Causes immediate exit from control structure
Used in while, for, do…while or switch statements
continue statement
Skips remaining statements in loop body
Proceeds to next iteration
Used in while, for or do…while statements

28. Logical Operators Logical operators Java logical operators
Allows for forming more complex conditions
Combines simple conditions
Java logical operators
&& (conditional AND)
|| (conditional OR)
! (logical NOT)

29. Logical Operators (Cont.)
Conditional AND (&&) Operator
Consider the following if statement
if ( gender == FEMALE && age >= 65 )
++s;
Combined condition is true
if and only if both simple conditions are true
Combined condition is false
if either or both of the simple conditions are false

30. Logical Operators (Cont.)
Conditional OR (||) Operator
Consider the following if statement
if (( Average >= 90)||(finalExam >= 90
System.out.println(“ grade is A ”);
Combined condition is true
if either or both of the simple condition are true
Combined condition is false
if both of the simple conditions are false

31. | Precedence/associatively of the operators discussed so far.

32. public class LogicalOperators{
public static void main( String args[] )
System.out.println("Conditional AND (&&)\n"+"false && false "+ ( false && false )+ "\nfalse && true "+ ( false && true )+ "\ntrue && false "+ ( true && false )+"\ntrue && true "+ ( true && true ) );
System.out.println("Conditional OR (||)\n"+"false || false "+( false || false )+ "\nfalse || true "+ ( false || true )+"\ntrue || false "+ ( true || false )+"\ntrue || true "+( true || true ) );
System.out.println("\nLogical NOT (!) "+"\n!false "+( !false )+ "\n!true "+ ( !true ) ); }