JAVA Variables and Operators
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The document discusses variables and operators in Java. It defines variables as containers that store data like numbers and letters, and notes that data types determine what values can be stored. It then covers various data types including primitive types like int and float, and reference types like Strings and Arrays. The document also discusses operators like arithmetic, logical, and assignment operators. It provides examples of declaring and using variables and operators in Java code.
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Binary operators
class ExampleAssignment {
public static void main(String[] args) {
int result, val_1, val_2;
result = (val_1 = 1) + (val_2 = 2);
System.out.println("val_1 = "+val_1);
System.out.println("val_2 = "+val_2);
System.out.println("result = "+result);
}
}
class ExampleAssignment {
public static void main(String[] args) {
int result, val_1, val_2;
result = (val_1 = 1) + (val_2 = 2);
System.out.println("val_1 = "+val_1);
System.out.println("val_2 = "+val_2);
System.out.println("result = "+result);
}
}
val_1 = 1
val_2 = 2
result = 3
val_1 = 1
val_2 = 2
result = 3](https://image.slidesharecdn.com/variablesnoperatorsv2-151128123150-lva1-app6891/85/JAVA-Variables-and-Operators-23-320.jpg)
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Binary operators
Expressions connected by && and || are
evaluated from left to right.
class ExampleAndOr {
public static void main(String[] args) {
int i=0;
System.out.println("Test:" + ((2<3) || (0<i++)));
System.out.println("I:" + i);
}
}
class ExampleAndOr {
public static void main(String[] args) {
int i=0;
System.out.println("Test:" + ((2<3) || (0<i++)));
System.out.println("I:" + i);
}
}
Test:true
I:0
Test:true
I:0
This never gets
evaluated!
This never gets
evaluated!](https://image.slidesharecdn.com/variablesnoperatorsv2-151128123150-lva1-app6891/85/JAVA-Variables-and-Operators-30-320.jpg)
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Mixing operators
class MixOperator {
public static void main(String[] args) {
char cv;
int iv1 = 64;
cv = (char) iv1;
System.out.println("cv:" + cv);
System.out.println("iv1:" + iv1);
}
}
cv:@
iv1:64](https://image.slidesharecdn.com/variablesnoperatorsv2-151128123150-lva1-app6891/85/JAVA-Variables-and-Operators-45-320.jpg)
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Mixing operators
class MixOperator1 {
public static void main(String[] args) {
double fv1, fv2;
int iv1 = 123;
fv1 = iv1/50;
fv2 = iv1/50.0;
System.out.println("fv1:" + fv1);
System.out.println("fv2:" + fv2);
}
}
fv1:2.0
fv2:2.46
fv1:2.0
fv2:2.46](https://image.slidesharecdn.com/variablesnoperatorsv2-151128123150-lva1-app6891/85/JAVA-Variables-and-Operators-46-320.jpg)
JAVA Variables and Operators
- 1. www.SunilOS.com 1 Variables & Operators www.sunilos.com www.raystec.com
- 2. Variables Variable stores human data like numbers and alphabets. Data type will decide what values will be stored in variables. You can say data type will define the structure of your data. www.SunilOS.com 2
- 3. Variables and Data Types Decimal values will be stored in float and double data type. Non-decimals values will be stored in int, long, byte, and short data types. Character will be stored in char data type. True/False will be stored in boolean data type. www.SunilOS.com 3
- 4. www.SunilOS.com 4 Data Types Data types are divided into two categories. Primitive Data Types o byte, short, int, long, float, double, boolean, char. o It occupies number of bytes as per data type. o It stores values. Reference Data Types o It stores memory address of a value. o It occupies 2 bytes to store a reference (memory address). o Strings, Objects, Arrays are reference data types.
- 5. www.SunilOS.com 5 Primitive Data Types int long byte short float double 1 2 4 8 4 8 -128, +127 -9.223E18, +9.223E18 -32768, +32767 -2147483648, +2147483647 +3.4 E+38 +1.7 E+308 Type Size Byte Range char 2 0, 65535 boolean 1 true, false 0 0 0 0 0 0 0 false Default
- 6. www.SunilOS.com 6 Declare Variable int total; total = 5+6; short srt; srt = 3; char ch; ch =‘A’ ; 4 Bytes Stack Memory1001 total 1001 11 2 Bytes 1011 3 srt 1011 2 Bytes 1010 A ch 1010
- 7. www.SunilOS.com 7 Declare Object int total; total = 5+6; String str; str = “sunRays”; o or str = new String(“sunRays”); 4 Bytes Stack Memory 1001 total 1001 11 2 Bytes 1011 1010 str 1011 14 Bytes 1010 SUNRAYS
- 8. www.SunilOS.com 8 Declare Variable – Primitive Data int total; total = 5+6; int newTotal; newTotal = total ; newTotal = newTotal+3 ; 4 Bytes Stack Memory1001 total 1001 11 4 Bytes 1011 newTotal 1011 1114
- 9. www.SunilOS.com 9 Declare Object - Copy reference String str; str = “sunRays” Or str = new String(“sunRays”) String newStr; newStr = str; Stack Memory 2 Bytes 1011 1010 str 1011 14 Bytes 1010 SUNRAYS 2 Bytes 1110 1010 newStr 1110
- 10. Java Identifier It is a name of: o Variable o Method o Class o Interface o Package Used to identify a variable, method and class in its scope. www.SunilOS.com 10
- 11. www.SunilOS.com 11 Java Identifier Rules Name of an Identifier follows certain rules. Here are key rules: o The first character must be a non-digit character from the Unicode standard String firstName; o Subsequent characters may include digits int total123 ; o Java is case sensitive that means Character Case is significant • int count =0 ; Count = 1 ; are two different variables o Avoid using underscore (_) and $ for the first character. o User-defined identifiers can not duplicate Java keywords.
- 12. www.SunilOS.com 12 What’s an operator? Operators are tokens that trigger some computation when applied to variables and other objects. It can be categorized into: o Arithmetic o logical o bit-level and o Class access operators.
- 13. www.SunilOS.com 13 Java operators () ++ -- ! ~ instance of * / % + - << >> >>> < > <= >= == != & ^ | && || ?: = op=
- 14. www.SunilOS.com 14 Operator Precedence int a = 2+ 4 + 8; int a = 2+ 4 * 8; int a = b = c = 5;
- 15. www.SunilOS.com 15 Operator Precedence Operators Precedence postfix expr++ expr-- unary ++expr --expr +expr -expr ~ ! multiplicative * / % additive + - shift << >> >>> relational < > <= >= instanceof equality == != bitwise AND & bitwise exclusive OR ^ bitwise inclusive OR | logical AND && logical OR || conditional ? : assignment = += -= *= /= %= &= ^= |= <<= >>= >>>=
- 16. www.SunilOS.com 16 Precedence Operators have the precedence. Higher precedence operator will be evaluated before the lower precedence operator. o int data = a * b + c ; since * (multiply) has higher precedence than + (plus) so a & b will be multiplied first then result will be added to c. Expression is equivalent to o int data = (a * b) + c ;
- 17. www.SunilOS.com 17 Unary operators ()() ++++ Group expression Unary plus Unary minus----
- 18. www.SunilOS.com 18 Unary operators ~~~~ !!!! ++++++++ -------- Bitwise complement Logical negation Pre- or Post-increment Pre- or Post-decrement
- 19. www.SunilOS.com 19 Unary operators i = 0; count = 2 + i++; i = 0; count = 2 + i++; ii countcount 11 22 i = 0; count = 2 + ++i; i = 0; count = 2 + ++i; ii countcount 11 33
- 20. www.SunilOS.com 20 Binary operators yyyy OperandOperand xxxx OperandOperand OperatorOperator
- 21. www.SunilOS.com 21 Binary operators ++ -- ** // Plus Minus Multiply Divide Remainder Additive & Multiplicative %%
- 22. www.SunilOS.com 22 Binary operators == AssignmentAssignment Assignment is an binary operator in Java. The left-hand operand of an assignment must be an LVALUE. An LVALUE is an expression that refers to a region of memory. o Names of variables are LVALUES. o Names of functions and arrays are NOT LVALUES.
- 23. www.SunilOS.com 23 Binary operators class ExampleAssignment { public static void main(String[] args) { int result, val_1, val_2; result = (val_1 = 1) + (val_2 = 2); System.out.println("val_1 = "+val_1); System.out.println("val_2 = "+val_2); System.out.println("result = "+result); } } class ExampleAssignment { public static void main(String[] args) { int result, val_1, val_2; result = (val_1 = 1) + (val_2 = 2); System.out.println("val_1 = "+val_1); System.out.println("val_2 = "+val_2); System.out.println("result = "+result); } } val_1 = 1 val_2 = 2 result = 3 val_1 = 1 val_2 = 2 result = 3
- 24. www.SunilOS.com 24 Binary operators Expressions involving only integers are evaluated using integer arithmetic. float result; int i,j; i=25; j=10; result = i/j; float result; int i,j; i=25; j=10; result = i/j; resultresult 2.02.0
- 25. www.SunilOS.com 25 Binary operators Expressions involving only integers are evaluated using integer arithmetic. float result; int i,j; i=25; j=10; result = (float) i/j; float result; int i,j; i=25; j=10; result = (float) i/j; resultresult 2.52.5
- 26. www.SunilOS.com 26 Binary operators +=+= -=-= *=*= /=/= Assign sum Assign difference Assign product Assign quotient Assign remainder%=%=
- 27. www.SunilOS.com 27 Binary operators Compound operators provide a convenient shorthand. int i; i = i + 5; i += 5; int i; i = i + 5; i += 5;
- 28. www.SunilOS.com 28 Binary operators << >> <=<= >=>= Less than Greater than Less than or equal to Greater than or equal to Equal to Not equal to Relational == == !=!=
- 29. www.SunilOS.com 29 Binary operators &&&& |||| Logical AND Logical OR Logical Expressions connected by && and || are evaluated from left to right.
- 30. www.SunilOS.com 30 Binary operators Expressions connected by && and || are evaluated from left to right. class ExampleAndOr { public static void main(String[] args) { int i=0; System.out.println("Test:" + ((2<3) || (0<i++))); System.out.println("I:" + i); } } class ExampleAndOr { public static void main(String[] args) { int i=0; System.out.println("Test:" + ((2<3) || (0<i++))); System.out.println("I:" + i); } } Test:true I:0 Test:true I:0 This never gets evaluated! This never gets evaluated!
- 31. www.SunilOS.com 31 Bitwise Binary operators << >> & ^ Shift left Shift right Bitwise AND Bitwise XOR Bitwise OR unary bitwise complement unsigned right shift | ~ >>> These operators are less commonly used.
- 32. www.SunilOS.com 32 Unary bitwise complement 1 1 11 0 101 ~ 1 Byte 0 0 00 1 010 byte a = 10; byte b = ~a;
- 33. www.SunilOS.com 33 Left Shift << 1 1 01 0 101 << 1 Byte 1 0 10 0 001 byte a = 10; b = a<<2; 1 1
- 34. www.SunilOS.com 34 Right Shift >> 1 1 01 0 101 >> 1 Byte 1 0 10 1 100 byte a = 10; b = a>>2; 1 0
- 35. www.SunilOS.com 35 Unsigned Right Shift >>> 1 1 01 0 101 >>> 1 Byte 0 0 11 1 100 byte a = 10; b = a>>>2; 1 0
- 36. www.SunilOS.com 36 And bitwise & 1 1 01 0 101 & 1 Byte 0 0 11 1 100 byte a = 10; b = 20; c = a & b; 0 0 01 0 100
- 37. www.SunilOS.com 37 OR bitwise | 1 1 01 0 101 | 1 Byte 0 0 11 1 100 byte a = 10; b = 20; c = a | b; 1 1 11 1 101
- 38. www.SunilOS.com 38 XOR bitwise ^ 1 1 01 0 101 ^ 1 Byte 0 0 11 1 100 byte a = 10; b = 20; c = a ^ b; 1 1 10 1 001
- 39. www.SunilOS.com 39 Ternary operators a?x:ya?x:y “if a then x, else y” Conditional result = (x<y) ? x : y;result = (x<y) ? x : y;
- 40. www.SunilOS.com 40 Multiple Assignments int a = b = c = 10;
- 41. www.SunilOS.com 41 Exercise What is the result of int i = 0 ; System.out.println(++i + ++i + ++i + ++i + ++i + ++i); System.out.println(“” + ++i + ++i + ++i + ++i + ++i + ++i);
- 43. www.SunilOS.com 43 Small to Big data type Will be done automatically. oint i = 5; odouble d = i; oshort s = 10; oint i = s; olong l = i;
- 44. www.SunilOS.com 44 Big to Small data type When precision or data loss likely to happen then type casting is required. o double d = 5; o int i = (int)d; o short s = (short)i; o int i = 10; o float f = (float)i;
- 45. www.SunilOS.com 45 Mixing operators class MixOperator { public static void main(String[] args) { char cv; int iv1 = 64; cv = (char) iv1; System.out.println("cv:" + cv); System.out.println("iv1:" + iv1); } } cv:@ iv1:64
- 46. www.SunilOS.com 46 Mixing operators class MixOperator1 { public static void main(String[] args) { double fv1, fv2; int iv1 = 123; fv1 = iv1/50; fv2 = iv1/50.0; System.out.println("fv1:" + fv1); System.out.println("fv2:" + fv2); } } fv1:2.0 fv2:2.46 fv1:2.0 fv2:2.46
- 47. www.SunilOS.com 47 String to Other data type String str = “5.5” ; int i = Integer.parseInt(str); double d = Double.parseDouble(str); float f = Float.parseFloat(str); long l = Long.parseLong(str); String bStr = “true”; boolean b = Boolean.parseBoolean(bStr);
- 48. www.SunilOS.com 48 Other data type to String String str = String.valueOf(5); String str = String.valueOf(5.5); String str = String.valueOf(true); String str = String.valueOf(5L); String str = String.valueOf(5.5D);
- 49. Disclaimer This is an educational presentation to enhance the skill of computer science students. This presentation is available for free to computer science students. Some internet images from different URLs are used in this presentation to simplify technical examples and correlate examples with the real world. We are grateful to owners of these URLs and pictures. www.SunilOS.com 49