CSE 2006 - Programming in Java Lecture Notes PDF

CSE 2006 - Programming in Java Course Type: LP Credits: 3  Unit-1 Contents Java Introduction Java Hello World, Java JVM, JRE and JDK, Difference between C & C++, Java Variables, Java Data Types, Java Operators, Java Input and Output, Java Expressions & Block...

CSE 2006 - Programming in Java Course Type: LP Credits: 3  Unit-1 Contents Java Introduction Java Hello World, Java JVM, JRE and JDK, Difference between C & C++, Java Variables, Java Data Types, Java Operators, Java Input and Output, Java Expressions & Blocks, Java Comment Java Flow Control Java if...else, Java switch Statement, Java for Loop, Java for-each Loop, Java while Loop, Java break Statement, Java continue Statement  Difference between C & C++ C C++ C was developed by Dennis C++ was developed by Bjarne Ritchie between the year 1969 Stroustrup in 1979. and 1973 at AT&T Bell Labs. C does no support C++ supports polymorphism, polymorphism, encapsulation, encapsulation, and inheritance and inheritance which means because it is an object oriented that C does not support object programming language. oriented programming. C is a subset of C++. C++ is a superset of C. C contains 32 keywords. C++ contains 63 keywords. C++ is known as hybrid For the development of code, C language because C++ supports supports both procedural and procedural programming. object oriented programming p aradigms Data and functions are. Data and functions are separated in C because it is a encapsulated together in form procedural programming of an object in C++.  Difference between C & C++ C C++ Data is hidden by the C does not support information Encapsulation to ensure that hiding. data structures and operators are used as intended. Built-in data types is supported Built-in & user-defined data in C. types is supported in C++. C is a function driven language C++ is an object driven because C is a procedural language because it is an programming language. object oriented programming. Function and operator Function and operator overloading is not supported in overloading is supported by C+ C. +. C++ is an object-driven C is a function-driven language. language Functions in C are not defined Functions can be used inside a inside structures. structure in C++. Namespace features are not Namespace is used by C++, present inside the C. which avoid name collisions.  Difference between C & C++ C C++ Header file used by C++ is Header file used by C is stdio.h. iostream.h. Reference variables are not Reference variables are supported by C. supported by C++. Virtual and friend functions are Virtual and friend functions are not supported by C. supported by C++. C does not support inheritance. C++ supports inheritance. C++ focuses on data instead of Instead of focusing on data, C focusing on method or focuses on method or process. procedure. C provides malloc() and calloc() C++ provides new operator for functions for memory allocation and dynamic memory allocation, delete operator for memory de- and free() for memory de- allocation. allocation. Direct support for exception Exception handling is supported handling is not supported by C. by C++.  Difference between C & C++ C C++ scanf() and printf() functions cin and cout are used for are used for input/output in C. input/output in C++. C structures don’t have access C ++ structures have access modifiers. modifiers. C follows the top-down C++ follows the Bottom-up approach approach Strict type checking in done in C++. So many programs that There is no strict type checking run well in C compiler will result in C programming language. in many warnings and errors under C++ compiler. C does not support overloading C++ does support overloading  Java Variables A variable is a container which holds the value while the Java program is executed. A variable is assigned with a data type. Variable is a name of memory location. There are three types of variables in java: local, instance and static. There are two types of data types in Java: primitive and non-primitive. A variable is the name of a reserved area allocated in memory. In other words, it is a name of the memory location. It is a combination of "vary + able" which means its value can be changed. int data=50; //Here data is variable  Types of Variables There are three types of variables in Java: 1) Local Variable A variable declared inside the body of the method is called local variable. You can use this variable only within that method and the other methods in the class aren't even aware that the variable exists. A local variable cannot be defined with "static" keyword. 2) Instance Variable A variable declared inside the class but outside the body of the method, is called an instance variable. It is not declared as static. It is called an instance variable because its value is instance- specific and is not shared among instances. 3) Static variable A variable that is declared as static is called a static variable. It cannot be local. You can create a single copy of the static variable and share it among all the instances of the class. Memory allocation for static variables happens only once when the class is loaded in the memory.  Types of Variables Example to understand the types of variables in java public class A { static int m=100; //static variable void method() { int n=90; //local variable } public static void main(String args[]) { int data=50; //instance variable } }//end of class  Java Data Types Data types specify the different sizes and values that can be stored in the variable. There are two types of data types in Java: Primitive data types: The primitive data types include boolean, char, byte, short, int, long, float and double. Non-primitive data types: The non-primitive data types include Classes, Interfaces, and Arrays. Java Primitive Data Types In Java language, primitive data types are the building blocks of data manipulation. These are the most basic data types available in Java language. Java is a statically-typed programming language. It means, all variables must be declared before its Java Data Types  Java Data Types Data Default Default size Type Value boolean false 1 bit char '\u0000' 2 byte byte 0 1 byte short 0 2 byte int 0 4 byte long 0L 8 byte float 0.0f 4 byte double 0.0d 8 byte  Java Data Types Boolean Data Type The Boolean data type is used to store only two possible values: true and false. This data type is used for simple flags that track true/false conditions. The Boolean data type specifies one bit of information, but its "size" can't be defined precisely. Example: Boolean one = false Byte Data Type The byte data type is an example of primitive data type. It is an 8-bit signed two's complement integer. Its value-range lies between -128 to 127 (inclusive). Its minimum value is -128 and maximum value is 127. Its default value is 0. The byte data type is used to save memory in large arrays where the memory savings is most required. It saves space because a byte is 4 times smaller than an integer. It can also be used in place of "int" data type. Example: byte a = 10, byte b = -20  Java Data Types Short Data Type The short data type is a 16-bit signed two's complement integer. Its value-range lies between -32,768 to 32,767 (inclusive). Its minimum value is -32,768 and maximum value is 32,767. Its default value is 0. The short data type can also be used to save memory just like byte data type. A short data type is 2 times smaller than an integer. short s = 10000, short r = -5000 Int Data Type The int data type is a 32-bit signed two's complement integer. Its value-range lies between - 2,147,483,648 (-2^31) to 2,147,483,647 (2^31 -1) (inclusive). Its minimum value is - 2,147,483,648and maximum value is 2,147,483,647. Its default value is 0. The int data type is generally used as a default data type for integral values unless if there is no problem about memory. Example:  Java Data Types Long Data Type The long data type is a 64-bit two's complement integer. Its value-range lies between -9,223,372,036,854,775,808(- 2^63) to 9,223,372,036,854,775,807(2^63 -1)(inclusive). Its minimum value is - 9,223,372,036,854,775,808and maximum value is 9,223,372,036,854,775,807. Its default value is 0. The long data type is used when you need a range of values more than those provided by int. Example: long a = 100000L, long b = -200000L Float Data Type The float data type is a single-precision 32-bit IEEE 754 floating point.Its value range is unlimited. It is recommended to use a float (instead of double) if you need to save memory in large arrays of floating point numbers. The float data type should never be used for precise values, such as currency. Its default value is 0.0F. Example: float f1 = 234.5f  Java Data Types Double Data Type The double data type is a double-precision 64-bit IEEE 754 floating point. Its value range is unlimited. The double data type is generally used for decimal values just like float. The double data type also should never be used for precise values, such as currency. Its default value is 0.0d. Example: double d1 = 12.3 Char Data Type The char data type is a single 16-bit Unicode character. Its value-range lies between '\u0000' (or 0) to '\uffff' (or 65,535 inclusive).The char data type is used to store characters. Example: char letterA = 'A'  Java Operators Operators are symbols that perform operations on variables and values. For example, + is an operator used for addition, while * is also an operator used for multiplication. Operators in Java can be classified into 5 types: 1. Arithmetic Operators 2. Assignment Operators 3. Relational Operators 4. Logical Operators 5. Unary Operators 6. Bitwise Operators  Java Operators 1. Java Arithmetic Operators Arithmetic operators are used to perform arithmetic operations on variables and data. Operat Name Description Example or + Addition Adds together two values x+y - Subtraction Subtracts one value from x-y another * Multiplicatio Multiplies two values x*y n / Division Divides one value by another x/y % Modulus Returns the division remainder x % y ++ Increment Increases the value of a ++x variable by 1 -- Decrement Decreases the value of a https://www.w3schools.com/java/java_operators.asp --x variable by 1  Java Operators Java Logical Operators Logical operators are used to determine the logic between variables or values: Operator Name Description Example && Logical Returns true if both x < 5 && x < 10 and statements are true || Logical Returns true if one of the x < 5 || x < 4 or statements is true ! Logical Reverse the result, returns !(x < 5 && x < 10) not false if the result is true  Java Operators // Java Arithmetic operations import java.io.*; class arith { public static void main(String args[]) {try{ DataInputStream din=new DataInputStream(System.in); System.out.println("Enter the 2-no's"); int i=Integer.parseInt(din.readLine()); int j=Integer.parseInt(din.readLine()); System.out.println("addition is" + (i+j)); System.out.println("subtraction is" + (i-j)); System.out.println("multiplication is" + (i*j)); System.out.println("divisionion is" + (i/j)); System.out.println("modulo division is" +(i%j)); }catch(Exception e) {} } }  Java Operators // Java Arithmetic operations import java.io.*; class arith { public static void main(String args[]) {try{ BufferedReader d = new BufferedReader(new InputStreamReader(System.in)); System.out.println("Enter the 2-no's"); int i=Integer.parseInt(d.readLine()); int j=Integer.parseInt(d.readLine()); System.out.println("addition is" + (i+j)); System.out.println("subtraction is" + (i-j)); System.out.println("multiplication is" + (i*j)); System.out.println("divisionion is" + (i/j)); System.out.println("modulo division is" +(i%j)); }catch(Exception e) {} } }  Java Operators Java Operator Precedence Operator Category Precedence Type Unary postfix expr++ expr-- prefix ++expr --expr +expr -expr ~ ! Arithmetic multiplicative */% additive +- Shift shift > >>> Relational comparison < > = instanceof equality == != Bitwise bitwise AND & bitwise exclusive ^ OR bitwise inclusive | OR Logical logical AND && logical OR || Ternary ternary ?:  Java Operators https://www.javatpoint.com/operators-in-java  Java Operators Java Unary Operator The Java unary operators require only one operand. Unary operators are used to perform various operations i.e.: incrementing/decrementing a value by one negating an expression inverting the value of a boolean  Java Operators Java Unary Operator Example: ++ and -- public class OperatorExample{ public static void main(String args[]){ int x=10; Output: System.out.println(x++);//10 (11) 10 System.out.println(++x);//12 12 System.out.println(x--);//12 (11) 12 System.out.println(--x);//10 10 }}  Java Operators Java Unary Operator Example 2: ++ and -- public class OperatorExample{ public static void main(String args[]){ int a=10; int b=10; Output: System.out.println(a++ + ++a);//10+12=2222 System.out.println(b++ + b++);//10+11=2121 }}  Java Operators Java Unary Operator Example: ! Outpu public class OperatorExample{ t: public static void main(String args[]){ false boolean c=true; true boolean d=false; System.out.println(!c); //false (opposite of boolean value) System.out.println(!d); //true }}  Java Operators Java Arithmetic Operator Example: Expression public class OperatorExample{ public static void main(String args[]){ System.out.println(10*10/5+3-1*4/2); }} Outpu t: 21  Java Operators Java Left Shift Operator The Java left shift operator 100 ) { if ( remainderOn == true) { myVal = mVal % 100; } else { myVal = myVal / 100.0; } } else { System.out.print(“myVal is in range”); }  else if Useful for choosing between alternatives: if ( n == 1 ) { // execute code block #1 } else if ( j == 2 ) { // execute code block #2 } else { // if all previous tests have failed, execute code block #3 }  The switch Statement switch ( n ) { case 1: // execute code block #1 break; case 2: // execute code block #2 break; default: // if all previous tests fail then //execute code block #4 break; }  The for loop Loop n times for ( i = 0; i < n; i++ ) { // this code body will execute n times // i from 0 to n-1 } Nested for: for ( j = 0; j < 10; j++ ) { for ( i = 0; i < 20; i++ ){ // this code body will execute 200 times } }  while loops while(response == 1) { System.out.print( “ID =” + userID[n]); n++; response = readInt( “Enter “); }  do {… } while loops do { System.out.print( “ID =” + userID[n] ); n++; response = readInt( “Enter ” ); }while (response == 1);  Break A break statement causes an exit from the innermost containing while, do, for or switch statement. for ( int i = 0; i < maxID, i++ ) { if ( userID[i] == targetID ) { index = i; break; } } // program jumps here after break  Continue Can only be used with while, do or for. The continue statement causes the innermost loop to start the next iteration immediately for ( int i = 0; i < maxID; i++ ) { if ( userID[i] != -1 ) continue; System.out.print( “UserID ” + i + “ :” + userID); }  Arrays An array is a collection of similar items An array has a fixed: – name – type – length These must be declared when the array is created. Arrays sizes cannot be changed during the execution of the code myArray 3 6 3 1 6 3 4 1 = 0 1 2 3 4 5 6 7 myArray has room for 8 elements the elements are accessed by their index in Java, array indices start at 0  Declaring Arrays int myArray[]; declares myArray to be an array of integers myArray = new int; sets up 8 integer-sized spaces in memory, labelled myArray to myArray int myArray[] = new int; combines the two statements in one line  Assigning Values refer to the array elements by index to store values in them. myArray = 3; myArray = 6; myArray = 3;... can create and initialise in one step: int myArray[] = {3, 6, 3, 1, 6, 3, 4, 1}; Iterating Through Arrays for loops are useful when dealing with arrays: for (int i = 0; i < myArray.length; i++) { myArray[i] = getsomevalue(); }  Multi Dimensional Array Two dimensional array: data_type[][] array_name = new data_type[x] [y]; For example: int[][] arr = new int; or Int arr[][]= new int; Three dimensional array: int[][][] threeD_arr = new int;  Declaring the Array 1. Declare the array private Student studentList[]; – this declares studentList 2.Create the array studentList = new Student; – this sets up 10 spaces in memory that can hold references to Student objects 3. Create Student objects and add them to the array: studentList = new Student("Cathy", "Computing");