Info Tech Guide

• The if-then and if-then-else Statements
• The switch Statement
• The while and do-while Statements
• The for Statement

• Variable names are case-sensitive. A variable's name can be any legal identifier — an unlimited-length sequence of Unicode letters and digits, beginn(Winwith a letter, the dollar sign "$", or the underscore character "_". The convention, however, is to always begin your variable names with a letter, not "$" or "_". Additionally, the dollar sign character, by convention, is never used at all. You may find some situations where auto-generated names will contain the dollar sign, but your variable names should always avoid using it. A similar convention exists for the underscore character; while it's technically legal to begin your variable's name with "_", this practice is discouraged. White space is not permitted.

• byte: The byte data type is an 8-bit signed two's complement integer. It has a minimum value of -128 and a maximum value of 127 (inclusive). The byte data type can be useful for saving memory in large arrays, where the memory savings actually matters. They can also be used in place of int where their limits help to clarify your code; the fact that a variable's range is limited can serve as a form of documentation.
• short: The short data type is a 16-bit signed two's complement integer. It has a minimum value of -32,768 and a maximum value of 32,767 (inclusive). As with byte, the same guidelines apply: you can use a short to save memory in large arrays, in situations where the memory savings actually matters.
• int: The int data type is a 32-bit signed two's complement integer. It has a minimum value of -2,147,483,648 and a maximum value of 2,147,483,647 (inclusive). For integral values, this data type is generally the default choice unless there is a reason (like the above) to choose something else. This data type will most likely be large enough for the numbers your program will use, but if you need a wider range of values, use long instead.

An array of ten elements

The Java programming language provides operators that perform addition, subtraction, multiplication, and division. There's a good chance you'll recognize them by their counterparts in basic mathematics. The only symbol that might look new to you is "%", which divides one operand by another and returns the remainder as its result.

+ additive operator (also used for String concatenation)
- subtraction operator
* multiplication operator
/ division operator
% remainder operator

The unary operators require only one operand; they perform various operations such as incrementing/decrementing a value by one, negating an expression, or inverting the value of a boolean.

+ Unary plus operator; indicates positive value (numbers are positive without this, however)
- Unary minus operator; negates an expression
++ Increment operator; increments a value by 1
-- Decrement operator; decrements a value by 1
! Logical complement operator; inverts the value of a boolean

The equality and relational operators determine if one operand is greater than, less than, equal to, or not equal to another operand. The majority of these operators will probably look familiar to you as well. Keep in mind that you must use "==", not "=", when testing if two primitive values are equal.
== equal to
!= not equal to
> greater than
>= greater than or equal to
< less than <= less than or equal to

The && and || operators perform Conditional-AND and Conditional-OR operations on two boolean expressions. These operators exhibit "short-circuiting" behavior, which means that the second operand is evaluated only if needed.

&& Conditional-AND
|| Conditional-OR

class ConditionalDemo1 {

public static void main(String[] args){
int value1 = 1;
int value2 = 2;
if((value1 == 1) && (value2 == 2)) System.out.println("value1 is 1 AND value2 is 2");
if((value1 == 1) || (value2 == 1)) System.out.println("value1 is 1 OR value2 is 1");

Different Operators Use in Java
The following quick reference summarizes the operators supported by the Java programming language.
Simple Assignment Operator
= Simple assignment operator

Arithmetic Operators
+ Additive operator (also used for String concatenation)
- Subtraction operator
* Multiplication operator
/ Division operator
% Remainder operator

for Statement
class ForDemo {
public static void main(String[] args){
for(int i=1; i<11; i++){
System.out.println("Count is: " + i);
}
}
}
The output of this program is:
Count is: 1
Count is: 2
Count is: 3
Count is: 4
Count is: 5
Count is: 6
Count is: 7
Count is: 8
Count is: 9
Count is: 10
Count is: 7
Count is: 8
Count is: 9
Count is: 10

while Statements

class WhileDemo {
public static void main(String[] args){
int count = 1;
while (count < 11) {
System.out.println("Count is: " + count);
count++;
}
}
}


do-while Statements

class DoWhileDemo {
public static void main(String[] args){
int count = 1;
do {
System.out.println("Count is: " + count);
count++;
} while (count <= 11);
}
}

Switch Statement

class SwitchDemo {
public static void main(String[] args) {

int month = 8;
switch (month) {
case 1: System.out.println("January"); break;
case 2: System.out.println("February"); break;
case 3: System.out.println("March"); break;
case 4: System.out.println("April"); break;
case 5: System.out.println("May"); break;
case 6: System.out.println("June"); break;
case 7: System.out.println("July"); break;
case 8: System.out.println("August"); break;
case 9: System.out.println("September"); break;
case 10: System.out.println("October"); break;
case 11: System.out.println("November"); break;
case 12: System.out.println("December"); break;
default: System.out.println("Invalid month.");break;
}
}
}

The if-then Statement
 void applyBrakes(){
if (isMoving){ // the "if" clause: bicycle must moving
currentSpeed--; // the "then" clause: decrease current speed
}
}
void applyBrakes(){
if (isMoving) currentSpeed--; // same as above, but without braces
}