Reference Learning Java DDC publishing Herst, Yamauchi, Adler COP 3331 Object Oriented Analysis and Design Java Part I

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I // First Java Program // HelloWorld.java Public class HelloWorld { public static void main (String args[]) { System.out.println(“Hello World!”); }

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I The following compile sequence occurs in Unix on Diablo. HelloWorld.java HelloWorld Hello World!

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I FileDefinitionFunction javac.exeThe Java compiler Converts Java source code into executable byte-code java.exeThe Java enterpreter Runs the java program appletview.exeThe applet viewLocally runs a java applet from within an HTML file. jdb.exeThe Java debugger Used to debug your Java applications and applets javah.exeThe Java C header and stub file generator Creates C header files and C stub files from a java class, allowing your java and C code to interact. javap.exeThe Java class file disassembler Converts a compiled class back into source code. javadoc.exeThe Java API documentation generator Generates HTML documentation from Java Source Code Primary Java Program Files

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I General Java points to remember: –Java is case sensitive. –Use ; (semicolon) to terminate lines of code. –Use { } (curly braces) to indicate blocks of code for classes, methods, if statements, and loops. –Use spaces for indentation to make your code more readable.

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I Commen t TypeFunction //C++Everything after the // and until the end of the line is treated as a comment. /* */CEverything between the /* and */ is treated as a comment even if it crosses a line boundary. /** */HypertextSame as the C style comments except that these comments are read by Java’s documentation generator, which can generated HTML code from your comments. You can include HTML code in these comments.

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I Memory variables: Storage space declared inside the computer on memory is allocated through memory variables and constants. Java is strongly typed which means that memory variables can only hold their declared type of data. There are two types of data catetories: –Simple types. –Object types.

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I TypeSize byte8 bits char16 bits (unsigned) short16 bits int32 bits long64 bits float32 bits double64 bits boolean1 bit Simple data types are not based on any other type. These sizes do not vary from machine to machine. All numeric types are signed except character. Java is case sensitive. Names of simple data types Are in lower case as shown. Simple Types

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I Declaring Variables Format: data_type variable_name; data_type variable_name =value; Example: int j; // integer char opt; // character short I; // short integer long L; // long integer float F; // real number double D; // 64 bit real number boolean ok; // True/False int I,j,k,l; char Men = “A”;

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I OperatorMeaningExample -Unary negationx = -y; +Additionx= y + z + x; -Subtractionx=y-z-x; *Multiplicationz = x * y; /Divisionz = x / y; %Modulusn = x % 3; ++Increment by 1x++; ++y; --Decrement by 1x--; Note: There is not operator for exponent. You must use the Math.pow() function for this task. Arithmetic Operators

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I OperatorMeaningExample !=Not Equalif(x != 100) y=Z; <Less thenif(x < 100) y=Z; <=Less then or equal toif(x <= 100) y=Z; >Greater thenif(x > 100) y=Z; >=Greater then or equal to if( <= 100) y=Z; !NotAnswer = !Answer; &Andif( x=100 & y==0 ) y=Z; |Orif( x=100 | y==0 ) y=Z; ^Exclusive Orif( x=100 ^ y==0 ) y=Z; &&Short circuit Andif (x <3 && y==0) z=7; ||Short circuit ORif (x <3 || y==0) z=7; Comparison and logical Operators On the short circuit operators, the next comparison is not accomplished if it does not affect the outcome.

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I OperatorMeaningExample ~Bitwise compliment x = ~x; //flips each bit. &Bitwise Andif(y&2 == 2) |Bitwise Orx = 3|5; // result 7 ^Bitwise Xorx=3^5; // Result 6 <<Left Shiftx = 1<<2; // Result 4 >>Sign propagating right shift I = 8>> 2; // Result 2 >>>Zero-fill right shift I = 8 >>>2;// result 2

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I Conditional Execution if(condition) statement; if(condition) { statement1; statement 2; statemetn 3; etc; }

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I if(condition) { statement1; statement2; } else { statement1; statement2; }

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I Switch Statements switch (expression) { case value1: statements; case value2: statements;... default: statements; } switch (input_char) { case ‘y’: System.out.print(“Entered y”); case ‘n’: System.out.print(“Entered n”); default: System.out.print(“Don’t know”); }

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I Loops for (initialize; condition; increment) { statements; } example: for (i=1; i<100; i++) { System.out.print(i); }

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I while (condition) { statements; } while (J < 100) { { J = J + 1; System.out.print(J); }

Reference Learning Java DDC publishing Herst, Yamauchi, Adler Java Part I Command Line Arguments: In all Java applications, the main() function accepts an argument, an array of strings called args[]; This array contains command line arguments. For instance, if you entered the following on the HelloWorld program: java HelloWorld Arg1 Arg2 “Hello Again” The args.length would equal three (3). and the contents would be: args[0] -> “Arg1” args[1] -> “Arg2” args[2] -> “Hello Again”