Sahar Mosleh California State University San MarcosPage 1 Data Types and Operators

Sahar Mosleh California State University San MarcosPage 2 Java is a strongly types language all operations are types checked by the compiler for type compatibility illegal operations will not be compiled Java contains two sets of data types object-oriented data types non-object-oriented data types Java object- oriented data types are defined by classes. Discussion of these types will be done later in the course

Sahar Mosleh California State University San MarcosPage 3 Primary data types Primary data types in Java are: booleanRepresents true or false value byte8-bit integer charCharacter doubleDouble-precision floating point floatsingle-precision floating point intinteger longLong integer shortShort integer

Sahar Mosleh California State University San MarcosPage 4 Character variables can be handles like integers class CharArithDemo{ public static void main(String args[]) { char ch; ch = ‘X’; System.out.println (“ch contains ” + ch); ch++; // increment ch System.out.println (“ch is now ” + ch); ch = 90; // give ch the value Z System.out.println( “ch is now ” + ch); } A char can be incremented A char can be assigned an integer value Note that although char is not integer type, in some case it can handled as integer Output: Ch contains X Ch is now Y ch is now Z

Sahar Mosleh California State University San MarcosPage 5 Boolean type Boolean types represents true/false. true and false are reserved words in Java class BoolDemo {public static void main(String args[]){ boolean b; b = false; System.out.println(“ b is: ” + b); b = true; System.out.println(“b is: ” + b); // a boolean value can control the if statement b = false; if (b) System.out.println(“This is not executed.”); // outcome of a relational operator is a boolean value System.out.println(“10 > 9 is ” + (10 > 9) ); } Output: b is false b is true 10 > 9 is true

Sahar Mosleh California State University San MarcosPage 6 More on variables Initializing a variable: One way to give a variable a value is through assignment statement For example, int count = 10; // giving count initial value of 10 char ch = ‘X’; // initializing ch to the value of ‘X’ floatf = 1.3F // f is initialized with 1.2 You can also declare two or more variables of the same type using comma-separated list For example, inta, b = 8, c = 19, d; // b and c are initialized

Sahar Mosleh California State University San MarcosPage 7 Operator Java has four different classes of operator: arithmetic, bitwise, relational, and logical Arithmetic operators include: + addition -subtraction *multiplication /division %module ++increment --decrement *, -, +, /, work mainly the same as other languages. % is the module operator. It works both for integer and floating- point numbers

Sahar Mosleh California State University San MarcosPage 8 class ModDemo { public static void main(String args[]) { int iresult, irem; double dresult, drem; iresult = 10 / 3; irem = 10 % 3; drem = 10.0 % 3.0; dresult = 10.0 / 3.0; System.out.println(“Result and remainder of 10/3: ” + iresult + “ ”+ irem); System.out.println(“Result and remainder of 10.0 /3.0: ” + dresult + “ ” + drem); } output: Result and remainder of 10 / 3: 3 1 Result and remainder of 10.0 / 3.0:

Sahar Mosleh California State University San MarcosPage 9 Examples of increment and decrement: X++meansX = X XmeansX = X + 1 Y = X++means Y = X and X= X+1 Y = ++Xmeans X = X+1 and Y = X The same logic works for decrement (X-- )

Sahar Mosleh California State University San MarcosPage 10 Relational operators are: = =!= > = Logical operators are: &And |OR ^XOR ! Not The outcome of the relational operators is a boolean value The result of a logical operation is also of type boolean

Sahar Mosleh California State University San MarcosPage 11 Suppose p and q are two boolean objects (literal, variable, expression), the following truth table holds pqp&qp|q!p!q TTTTFF TFFTFT FTFTTF FFFFTT For example, suppose c is a boolean variables and x=10, y = 20 c = ( x > 15) && (y = =20) In this case since the first operand (x>15) is false, the result of c is false no matter what the result of the second operand (y==20) is.

Sahar Mosleh California State University San MarcosPage 12 The Assignment operator The assignment operator is the single equal sign =. The general format of assignment operator is: var = expression The type of expression should match the type of the variable It is also possible to create a chain of assignments For example: int x, y, z x = y = z = 100; In this case, going from right to left, 100 is assigned to z which in turn z is assigned to y and the value of y is assigned to x Java also supports assignments for the following logical operators +=-=*=%=&=|=^= For example, a+=b means a = a + b