1. 4.1 Object Operations

2. 4.1.1 operators
• Dot ( . ) and new operate on objects
• The assignment operator ( = )
• Arithmetic operators + - * / %
• Unary operators ++, --, *=, %=
• Operator precedence
• Arithmetic expressions are left associative
• Assignment operators are right associative

3. 4.2.6 Boolean data and comparison
operators
• boolean values are true or false ( not 1 or 0)
• Less than <, greater than >, equal to ==, less
than or equal to <=, greater than or equal to >=,
not equal !=
• AND &, OR |, XOR ^
• Short curcuit AND &&, OR ||

4. 4.2.8 Conditional operator
• Alternative for if - else
y = x > 4 ? 99: 9;
Is the same as:
if(x > 4)
y = 99;
else
y = 9;

5. 4.2.9 Bitwise operators
• Perform shifting of bits on integral types,
preferably int of long
• <<3 shifts all bits left 3 places. All new bits are 0
• >>>3 shifts all bits right 3 places. All new bits
are 0
• >>3 shifts all bits right 3 places. The new bits
are the same as the most significant bit before
the shift.

6. 4.3.1 Casting and conversion
• Casting assigns a value of one type to a
variable of another type
• If it is possible to lose information, an explicit
cast is required
long bigValue = 99L;
int squashed = (int)bigValue;

7. 4.4.2 String and StringBuffer class
• The String object can be used to store an
arbitrary number of textual characters
• Strings are immutable: They do not change
• Concatenating two Strings results in the
creation of another String
• Use StringBuffer to hold Strings that will
change

8. 4.5.1 Decision making and
repetition
• Control structures control the flow of statement
execution
• Three control structures: Sequence, selection
or decision, repetition
• In OOP, control structures exist within methods
only
• Selection control structure provides conditional
execution (if-else)
• Repitition control structure causes the computer
to repeat certain actions (for <loop>, while
<loop>, do <loop>)

9. 4.5.3 If statement
• Basic
if(x == 3) {
System.out.println(“x equals 3”);
}
else {
System.out.println(“x does not equal 3”);
}

10. 4.5.4 Multiple condition If
• Multiple condition
if(a < b) {
System.out.println(“a is less than b”);
}
else if (a < c) {
System.out println(“a is less than c”);
}
else {
System.out.println(“a is not less than b or c”);
}

11. 4.5.5 Nested if
• Nested If
if(x == 3) {
System.out.println(“x equals 3”);
if( y == 4) {
System.out.println(“ …and y equals 4”);
}
}
else {
System.out.println(“x does not equal 3”);
}

12. 4.5.6 Switch statements
• A conditional control structure that allows a value to be compared to
more than one other value
switch(test) {
case 1:
System.out.println(“test equals 1”);
break;
case 2:
System.out.println(“test equals 2”);
break;
case 3:
System.out.println(“test equals 3”);
break;
default:
System.out.println(“test does not equal 1, 2 or 3”);
break;
}

13. 4.5.7 Loop
• do while: Execution loops. Conditional
evaluation at the end of the loop
• while: Execution loops through the block.
Conditional evaluation occurs at the start of the
loop
• for next: Specifies an initialization block, a
conditional evaluation and a block that is
executed in every loop

14. 4.5.11 Use of break, continue, and
label
• break is used to exit a block
• continue is used to return to the start of the loop
• label can be applied to a statement or block,
then used with continue or break
• break can be used to exit a labeled block
• continue can be used to resume at a statement

15. 4.6.1 The java.lang.System class