The document discusses various concepts related to conditional statements and logical operators in Java. 1) It explains if, if-else statements and how they allow a program to make choices and execute different code blocks conditionally. Nested if statements and else-if ladder are also covered. 2) Logical operators like &&, || and ! are described which allow combining multiple boolean expressions. Truth tables for AND, OR and NOT operators are provided. 3) The conditional operator ?: is explained as another way to write conditional expressions in a single line. 4) The switch statement is summarized as providing an alternative to multiple if-else statements when checking discrete cases of a variable.

2.  Take the value from right hand side (rvalue) and
copy it into left hand side (lvalue)
 Rvalue
 Constant , variable or expression
 Lvalue
 Distinct, named variable

3. Operator Example Equivalent
+= i += 8 i = i + 8
-= f -= 8.0 f = f - 8.0
*= i *= 8 i = i * 8
/= i /= 8 i = i / 8
%= i %= 8 i = i % 8
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4.  Syntax Errors
 Detected by the compiler
 Runtime Errors
 Causes the program to abort
 Logic Errors
 Produces incorrect result
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5. A pair of braces in a program forms a block that
groups components of a program.
public class Test {
Class block
public static void main(String[] args) {
System.out.println("Welcome to Java!"); Method block
}
}
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6. Eihter next-line or end-of-line style for braces.
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7. Specifier Output Example
%b a boolean value true or false
%c a character 'a'
%d a decimal integer 200
%f a floating-point number 45.460000
%e a number in standard scientific notation 4.556000e+01
%s a string "Java is cool"
int count = 5;
items
double amount = 45.56;
System.out.printf("count is %d and amount is %f", count, amount);
display count is 5 and amount is 45.560000
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8. Description Escape Sequence
Backspace b
Tab t
Linefeed n
Carriage return r
Backslash
Single Quote '
Double Quote "
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9. Java in two semesters by Quentin Charatan & Aaron Kans

10.  The order in which the instructions were executed
was not under your control
 Program starts by executing the first instruction in
main method and then all executed instructions
were in sequence
 This order of execution is restrictive and one as
programmer need more control over the order in
which the instructions are executed

11. Generates boolean result
Evaluates relationship between
values of the operands
 Produces TRUE if relationship is true
 Produces FALSE is relationship is untrue

12. Operator Meaning
== Equal to
!= Not equal to
< Less than
> Greater than
>= Greater than or equal to
<= Less than or equal to

14.  Whenever we need to make choice among
different courses of action
 Example
 A program processing requests for airline tickets
could have following choices to make
 Display the price os seats requested
 Display a list of alternative flights
 Display a message saying that no flights are available to
that destination
A program that can make choices can behave
differently each time it is run, whereas programs
run in sequence behave the same way each time
they are run
 Unless otherwise mentioned, program instructions
are executed in sequence

16.  Some of the instruction need a guard so that they
are executed only when appropriate
 JAVA if statement
 Syntax
if(/* a test goes here*/)
{
// instruction (s) to be guarded go here
}
 The braces indicate the body of if statement
 If statement must follow the round brackets and
condition is placed inside these brackets
 Condition/expression gives a boolean result of true or
false

17. import java.util.Scanner;
public class Assignment1 {
public static void main(String[] args) {
int x = 0;
Scanner scan = new Scanner(System.in);
x = scan.nextInt();
if(x%2 == 0)
{
System.out.println("number is even");
}
}
}

18. import java.util.Scanner;
public class Assignment1 {
public static void main(String[] args) {
int temperature = 0;
Scanner scan = new Scanner(System.in);
temperature = scan.nextInt();
if(temperature<0)
{
System.out.println("its freezing");
System.out.println("temperature is: "+temperature);
System.out.println("Wear appropriate clothes");
}
}
}

19.  Single – branched instructions
 The if statement provides two choices
 Execute the conditional instructions
 Condition is true
 Do not execute the conditional instructions
 Condition is false
 Do nothing

20.  Double branched selection
 Alternative course of action
 Choices
 Some instructions are executed if condition is true
 Some other instructions are executed if condition is
false

21. import java.util.Scanner;
public class Assignment1 {
public static void main(String[] args) {
int x = 0;
Scanner scan = new Scanner(System.in);
x = scan.nextInt();
if(x%2 == 0)
{
System.out.println("number is even");
}
else
{
System.out.println("number is odd");
}
System.out.println(“good work");
}
}

23.  int n1 = 15;
 int n2 = 15;
 System.out.println(n1==n2);
 System.out.println(n1!=n2);

24.  Often it is necessary to join two or more tests
together to create a complicated test
 Consider a program that checks the temperature in
laboratory. To have a successful experiment it is
required that the temperature remain between 5
and 12
 The test need to check
 Temperature is greater than or equal to 5
 Temperature>=5
 Temperature is less than or equal to 12
 Temperature <=12
 Both of these tests need to evaluate true in order to
provide the right environment

25. Logical Operator Java Counterpart
AND &&
OR ||
NOT !
Produces a boolean value of true or false based
on logical relationship of arguments
Allowed in between of boolean values only
Conditions generate boolean result

26. A = Result A = Result A && B
of 1st of 2nd
Expression Expression
True True True
True False False
False True False
False False False

27. A = Result A = Result A || B
of 1st of 2nd
Expression Expression
True True True
True False True
False True True
False False False

28. X !X
TRUE FALSE
FALSE TRUE

29. import java.util.Scanner;
public class Assignment1 {
public static void main(String[] args) {
int temperature = 0;
Scanner scan = new Scanner(System.in);
temperature = scan.nextInt();
if(temperature>=5 && temperature <=12)
{
System.out.println("environment is safe");
}
else
{
System.out.println("environment is not safe");
}
}
}

30. In Java
If a value is zero, it can be used as the logical
value false.
If a value is not zero, it can be used as the
logical value true.
Zero <===> False
Nonzero <===> True

31.  Expression will be evaluated only until the truth or
falsehood of the entire expression can be
unambiguously determined
 Latter parts of the logical expression might not be
evaluated

32. Expression Result Explanation
10>5 && 10>7 True Both results are true
10>5 && 10>20 False The second test is false
10>15 && 10>20 False Both tests are false
10>5 || 10>7 True At least one test is true
10>5 || 10>20 True At least one test is true
10>15 || 10>20 False Both tests are false
!(10>5) False Original test is true
!(10>15) True Original test is false

33.  Instructions within if and if…else statements can
themselves be any legal java commands
 It is also allowed that if statements contain other
if/if-else statements
 Nesting
 Allows multiple choices to be processed

35. public static void main(String[] args) {
int marks = 0;
Scanner scan = new Scanner(System.in);
marks = scan.nextInt();
if(marks <100)
{
if(marks>=80)
{
System.out.println("Grade = A");
}
else
{
if(marks>=60)
{
System.out.println("Grade = B");
}
else
{
System.out.println("Grade = F");
}
}
}
}

36. public static void main(String[] args) {
int marks = 0;
Scanner scan = new Scanner(System.in);
marks = scan.nextInt();
if(marks <100)
{
if(marks>=80)
{
System.out.println("Grade = A");
}
else if(marks>=60)
{
System.out.println("Grade = B");
}
else
{
System.out.println("Grade = F");
}
}
}

37. else is always paired
with the most recent,
unpaired if

40. Adding a semicolon at the end of an if clause is a
common mistake.
if (radius >= 0);
{
area = radius*radius*PI;
System.out.println(
"The area for the circle of radius " +
radius + " is " + area);
}
This mistake is hard to find, because it is not a
compilation error or a runtime error, it is a logic error.
This error often occurs when you use the next-line
block style.
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41.  Conditionaloperator
 Has three operands
 Boolean-exp? value0 : value1
import java.util.Scanner;
public class Assignment1
{
public static void main(String[] args) {
int marks = 0;
Scanner scan = new Scanner(System.in);
marks = scan.nextInt();
System.out.println(marks>=50? "Pass":"Fail");
}
}

43. public static void main(String[] args) {
int value = 0;
Scanner scan = new Scanner(System.in);
value = scan.nextInt();
switch(value)
{
case 1:
System.out.println("We are in case 1");
break;
case 2:
System.out.println("We are in case 2");
break;
case 3:
System.out.println("We are in case 3");
break;
default:
System.out.println("We are in case default");
//break;
}
}

44.  Only one variable is being checked in each
condition
 Check involves only specific values of that variable
and not ranges (>= or <= are not allowed)
 Switch statement condition carries the name of the
variable only
 The variable is usually of type int or char but can
also be of type long, byte or short
 break is optional command that forces the program
to skip the rest of switch statement
 Default is optional (last case) that can be thought
of as an otherwise statement.
 Deal with the possibility if none of the cases above is
true

47. Consider the following statements:
byte i = 100;
long k = i * 3 + 4;
double d = i * 3.1 + k / 2;
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48. When performing a binary operation
involving two operands of different types,
Java automatically converts the operand
based on the following rules:
1. If one of the operands is double, the other is
converted into double.
2. Otherwise, if one of the operands is float, the
other is converted into float.
3. Otherwise, if one of the operands is long, the
other is converted into long.
4. Otherwise, both operands are converted into
int.
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49. Implicit casting
double d = 3; (type widening)
Explicit casting
int i = (int)3.0; (type narrowing)
int i = (int)3.9; (Fraction part is
truncated)
What is wrong? int x = 5 / 2.0;
range increases
byte, short, int, long, float, double
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50. int i = 'a'; // Same as int i = (int)'a';
char c = 97; // Same as char c = (char)97;
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