4.1 Object Operations

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

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

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;

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.

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;

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

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, while, do )

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

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”); }

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”); }

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; }

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

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

4.6.1 The java.lang.System class