The Java compiler translates these tokens into Java bytecode. Further, these bytecodes are
executed inside the interpreted Java environment.
Types of Tokens
Java token includes the following:
o
Keywords
o
Identifiers
o
Literals
o
Operators
o
Separators
o
Comments
Keywords: These are the pre-defined reserved words of any programming language.
Each keyword has a special meaning. It is always written in lower case. Java provides the following
keywords:
w
01. abstract
02. boolean
03. byte
04. break
05. class
06. case
07. catch
08. char
09. continue
10. default
11. do
12. double
13. else
14. extends
15. final
16. finally
17. float
18. for
19. if
20. implements
21. import
22. instanceof
23. int
24. interface
25. long
26. native
27. new
28. package
29. private
30. protected
31. public
32. return
33. short
34. static
35. super
36. switch
37. synchronized
38. this
39. thro
40. throws
41. transient
42. try
43. void
44. volatile
45. while
46. assert
47. const
48. enum
49. goto
50. strictfp
Identifier: Identifiers are used to name a variable, constant, function, class, and array. It usually
defined by the user. It uses letters, underscores, or a dollar sign as the first character. The label is
also known as a special kind of identifier that is used in the goto statement. Remember that the
identifier name must be different from the reserved keywords. There are some rules to declare
identifiers are:
o
The first letter of an identifier must be a letter, underscore or a dollar sign. It cannot start with digits
but may contain digits.
o
The whitespace cannot be included in the identifier.
o
Identifiers are case sensitive.
Some valid identifiers are:
1.
PhoneNumber
2. PRICE
3. radius
4. a
5. a1
6. _phonenumber
7. $circumference
8. jagged_array
9. 12radius //invalid
Literals: In programming literal is a notation that represents a fixed value (constant) in the source
code. It can be categorized as an integer literal, string literal, Boolean literal, etc. It is defined by the
programmer. Once it has been defined cannot be changed. Java provides five types of literals are as
follows:
o
Integer
o
Floating Point
o
Character
o
String
o
Boolean
Literal
Type
23
int
9.86
double
false, true
boolean
'K', '7', '-'
char
"javatpoint"
String
null
any reference type
Operators: In programming, operators are the special symbol that tells the compiler to perform a
special operation. Java provides different types of operators that can be classified according to the
functionality they provide. There are eight types of operators in Java, are as follows:
o
Arithmetic Operators
o
Assignment Operators
o
Relational Operators
o
Unary Operators
o
Logical Operators
o
Ternary Operators
o
Bitwise Operators
o
Shift Operators
Operator
Symbols
Arithmetic
+,-,/,*,%
Unary
++ , - - , !
Assignment
= , += , -= , *= , /= , %= , ^=
Relational
==, != , < , >, <= , >=
Logical
&& , ||
Ternary
(Condition) ? (Statement1) : (Statement2);
Bitwise
&,|,^,~
Shift
<< , >> , >>>
Separators: The separators in Java is also known as punctuators. There are nine separators in Java,
are as follows:
1. separator <= ; | , | . | ( | ) | { | } | [ | ]
Note that the first three separators (; , and .) are tokens that separate other tokens, and the last six (3
pairs of braces) separators are also known as delimiters. For example, Math.pow(9, 3); contains nine
tokens.
o
Square Brackets []: It is used to define array elements. A pair of square brackets represents the
single-dimensional array, two pairs of square brackets represent the two-dimensional array.
o
Parentheses (): It is used to call the functions and parsing the parameters.
o
Curly Braces {}: The curly braces denote the starting and ending of a code block.
o
Comma (,): It is used to separate two values, statements, and parameters.
o
Assignment Operator (=): It is used to assign a variable and constant.
o
Semicolon (;): It is the symbol that can be found at end of the statements. It separates the two
statements.
o
Period (.): It separates the package name form the sub-packages and class. It also separates a variable
or method from a reference variable.
Comments: Comments allow us to specify information about the program inside our Java code. Java
compiler recognizes these comments as tokens but excludes it form further processing. The Java
compiler treats comments as whitespaces. Java provides the following two types of comments:
o
Line Oriented: It begins with a pair of forwarding slashes (//).
o
Block-Oriented: It begins with /* and continues until it founds */.
a=a-(a--)-(--a)
a=10-(10- 8)
a=10-2
a=8
L->R
When we try to assign a variable of large-sized type to a smaller sized type, Java will generate an error, incompatible types: possible lossy conversion, while
compiling the code.
public class ICSE2006_6
{
public static void main()throws Exception
{
String s="January 26 is celebrated as the Republic Day of India";
s=s.replace("January", "August");
s=s.replace("26", "15");
s=s.replace("Republic", "Independence");
System.out.println(s);
}
}
(f) What is the output of the following :
(a) System.out.println (“Append :” + 4 + 2);
(b) System.out.println (“Sum:” + (4+2));
Append:42
Sum: 6
(g) Evaluate the following expressions, if the values of the variables are a = 2, b = 3 and c = 9.
(i) a – (b++) *( – – c)
2 – 3*8
2-24
-22
(ii) a * (++b) % c
2*4%9
8%9
8
A package that is invoked by default. java.lang;
(ii) A keyword, to use the classes defined in package. import
Two types of Java Programs (i) Java applets (ii) Java applications
public class test
{
public static void main(String args[])
{
double p = Math.ceil(8.3) + Math.floor(-3.2)+Math.rint(4.5);
double q = Math.abs(Math.round(Math.max( -4.4, -9.6)));
System.out.println (q);
System.out.println (q);
}
}
In case of 0.5 at decimal places it will round off to nearest even double value.
public class test
{
public static void main(String args[])
{
String str1 = "great";
String str2= "Minds";
System.out.println(str1.substring(0,2).concat(str2.substring(1)));
System.out.println(( "WH"+(str1.substring(2).toUpperCase() )));
}
}
grinds WHEAT
State the two kinds of data types.
Ans: The two kinds of data types in Java are primitive and reference data types.
d. Define impure function.
Ans: Impure Function: A function that brings about a change in the argument that it receives. Its arguments will
always be reference types. It may or may not return value. In other words, an impure function brings about a
change in the state of the function. This change in state is called the side effect of calling an impure function.
What is wrapper class? Give example.
e. A wrapper class is a class that wraps a primitive data type. Example Double, Float, Integer
import java.util.*;
class series
{
public static void main(String arg[])
{
System.out.println("1.series_1 2.series_2 ");
Scanner sc=new Scanner(System.in);
System.out.println("enter your choice");
int choice=sc.nextInt();
switch(choice)
{
case 1: double sum=0.0;
int x=2;
for (int i=1;i<=20;i++)
{
if (i%2==0)
sum =sum-Math.pow(x,i);
else
sum =sum+Math.pow(x,i);
}
System.out.println("sum is ="+sum);
break;
case 2 : int s=0;
for(int i=1 ;i<=5 ;i++)
{
s=s*10+1 ;
System.out.print(s +" " );
}
break;
default :System.out.println("invalid choice");
}
}
}
class overload
{
public static void check(String s ,char ch)
{
int c=0;
for(int i=0;i<s.length();i++)
{
if(s.charAt(i)==ch)
c++;
}
System.out.println("number of "+ ch+ " present is="+c);
}
public static void check(String s1)
{
s1=s1.toLowerCase();
for(int i=0;i<s1.length();i++)
{
char ch = s1.charAt(i);
if (ch=='a'||ch=='e'||ch=='i'||ch=='o'||ch=='u')
System.out.print(ch+" ");
}
}
public static void main(String arg[])
{
check("success", 's');
check("computer");
}
}
public class Selection
{
String m[]=new String[40];
Selection(String z[])
{
m=z;
}
void sort()
{
int i, p, j; String s,t;
for (i=0;i<40;i++)
{
s=m[i];
p=i;
for (j=i+1;j<40;j++)
{
if (m[j].compareTo(s)>0)
{
s=m[j];
p=j;
}
}
t=m[i];
m[i]=m[p];
m[p]=t;
}
for (i=0;i<40;i++)
System.out.println(m[i]);
}
}
/* Program to Print Diamond Shape */
import java.util.Scanner;
public class Diamond
{
public static void main(String args[])
{
int n, i, j, space = 1;
System.out.print("Enter the number of rows: ");
Scanner s = new Scanner(System.in);
n = s.nextInt();
space = n - 1;
for (j = 1; j <= n; j++)
{
for (i = 1; i <= space; i++)
{
System.out.print(" ");
}
space--;
for (i = 1; i <= 2 * j - 1; i++)
{
System.out.print("*");
}
System.out.println("");
}
space = 1;
for (j = 1; j <= n - 1; j++)
{
for (i = 1; i <= space; i++)
{
System.out.print(" ");
}
space++;
for (i = 1; i <= 2 * (n - j) - 1; i++)
{
System.out.print("*");
}
System.out.println("");
}
}
}
/* Java Program to Check whether an inputted Number is Strontio or Not
i.e. 1386 * 2 = 2772 */
import java.util.*;
public class Strontio
{
public static void main(String args[])
{
Scanner sc=new Scanner(System.in);
System.out.print("Enter the number: ");
int num=sc.nextInt();
num=(num*2%1000)/10;
if(num%10==num/10)
System.out.println(n+ " is a strontio number.");
else
System.out.println(n+ " is not a strontio number.");
}
}
* Program to Print following pattern */
13579
35791
57913
79135
91357
public class test
{
public static void main(String args[])
{
int i,j,z=1,w;
for(i=1;i<=5;i++)
{
w=z;
for(j=1;j<=5;j++)
{
System.out.print(w%10);
w=w+2;
}
z=z+2;
System.out.println();
}
}
}
/* Java Program to Perform Basic String Operations */
import java.util.Scanner;
import java.util.Arrays;
public class StringMethods
{
public static void main(String args[])
{
Scanner sc=new Scanner(System.in);
System.out.println("Enter String-1");
String s1=sc.nextLine();
System.out.println("Enter String-2");
String s2=sc.nextLine();
System.out.println("Length of String-1 is:"+s1.length());
System.out.println("Length of String-2 is:"+s2.length());
System.out.println("String-1 in LowerCase-"+s1.toLowerCase());
System.out.println("String-2 in UpperCase-"+s2.toUpperCase());
System.out.println("Check s1 equals s2-"+s1.equals(s2));
System.out.println("Comapre s1 & s2:"+s1.compareTo(s2));
System.out.println("Chatracter of String at postion 0 is:"+s1.charAt(0));
String s3=s1.concat(s2);
System.out.println("Concatened String is:-"+s3);
System.out.println("Substring is:"+s3.substring(0,11));
System.out.println("After Replacing o with a-"+ s3.replace('o','a'));
System.out.println("Index of Character N is:"+s3.indexOf('n'));
}
}
/* Java Program to input 10 Name and bubble sort them */
import java.util.*;
public class test
{
public static void main(String args[])
{
String str="Sky Is Blue",word="";
str= str+"";//Append space for extracting last word
char ch= ' ';
int swl=str.length(); // Let Smallest Word Length is Entire Sentence Length
int mwl=0;
// Let Largest Word Length is Zero
String sword="", lword="";
for(int i=0;i<str.length();i++)
{
ch=str.charAt(i);
if(ch!=' ')
{
word+=ch;// Build Word from character Excluding spaces
}
else
{
if(word.length()< swl)//Checking for Smallest Word Length
{
swl=word.length();
sword=word;
}
if(word.length()> mwl)
{
mwl=word.length();
lword=word;
}
word="";// Emptying variable for forming next word
}
}
System.out.println("Smallest Word is " + sword + " having length=" + swl);
System.out.println("Largest Word is " + lword + " having length=" + mwl);
}
}
/* Java Program to Count Vowels and Consonant in a Sentence */
import java.util.*;
public class countconstvowel
{
public static void main(String args[])
{
int vowelcount=0,constcount=0;
String s="Noteshacker is an amazing website ";
s=s.toLowerCase();
for(int i=0;i<s.length();i++)
{
if(s.charAt(i)=='a'||s.charAt(i)=='e'||s.charAt(i)=='i'||s.charAt(i)=='o'|| s.charAt(i)=='u')
{
vowelcount++;
}
else if(s.charAt(i)>='a' && s.charAt(i)<='z')
{
constcount++;
}
}
System.out.println("Number of Vowels in the Sentences is:"+ vowelcount);
System.out.println("Number of Consonant in the Sentences is:"+ constcount);
}
}
/* Java Program to Count No. of words in a Sentence */
public class CountWords
{
public static void main(String[] args)
{
String str = "Sky is Blue";
int count = 1;
for (int i = 0; i < str.length() - 1; i++)
{
if ((str.charAt(i) == ' ') && (str.charAt(i + 1) != ' '))
{
count++;
}
}
System.out.println("Number of words in the string : " + count);
}
}
/*Program to accept a string. Convert the string to uppercase and Count the
number of double letter sequences that exist in the string.*/
import java.util.Scanner;
public class StringOperations
{
public static void main(String[] args)
{
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a String: ");
String input = scanner.nextLine();
input = input.toUpperCase();
int count = 0;
for (int i = 1; i < input.length(); i++)
{
if (input.charAt(i) == input.charAt(i - 1))
{
count++;
}
}
System.out.println(count);
}
}
}
/* Java Program to input 10 Name and bubble sort them */
import java.util.Scanner;
class BubbleSort
{
public static void main(String []args)
{
int i, j,n=10;
String temp;
Scanner in = new Scanner(System.in);
System.out.println("Input Ten Names in Random Order");
String names[] = new String[n];
for (i = 0; i < n; i++)
names[i] = in.nextLine();
for (i = 0; i < n; i++)
{
for (j = 0; j < n - i - 1; j++)
{
if (names[j].compareToIgnoreCase(names[j+1]) >0 )
{
temp
= names[j];
names[j]
= names[j+1];
names[j+1] = temp;
}
}
}
System.out.println("Sorted Names :");
for (i = 0; i < 10; i++)
System.out.println(names[i]);
}
}
int a=6,b=5;
a += a++ % b++ *a + b++* --b;
a += a++ % b++ *a + b++* --b
=> a = a + (a++ % b++ *a + b++* --b)
=> a = 6 + (6 % 5 * 7 + 6 * 6)
// % and * will be applied first due to higher precedence
=> a = 6 + (7 + 36)
=> a = 49
(c) Give the output of the snippet:
int a=10,b=12;
if(a==10&&b<=12)
a--;
else
++b;
System.out.println(a + "and" +b);
(b) Write a program to display the given pattern:
11111
3333
555
77
9
public class KboatPattern
{
public static void main(String args[]) {
for (int i = 5, term = 1; i >= 0; i--, term += 2) {
for (int j = 1; j <= i; j++) {
System.out.print(term + " ");
}
System.out.println();
}
}
}
(b) Write a program to display the given pattern:
3
56
8 9 10
12 13 14 15
public class KboatPattern
{
public static void main(String args[]) {
int t = 2;
for (int i = 1, j = 1; i <= 4; i++, j++) {
t += i;
for (int k = t, l = 1; l <= j; k++, l++)
System.out.print(k + " ");
System.out.println();
}
}
}
import java.util.Scanner;
public class KboatDigitSum
{
public static void main(String args[]) {
Scanner in = new Scanner(System.in);
System.out.print("Enter a number: ");
int n = in.nextInt();
int sum = 0, count = 0;
while (n != 0) {
int d = n % 10;
sum += d;
count++;
n /= 10;
}
System.out.println("Sum of digits = " + sum);
System.out.println("Number of digits = " + count);
}
}
Primitive Data Types
A primitive data type specifies the size and type of variable values, and it has no additional
methods.
There are eight primitive data types in Java:
Data
Type
byte
short
int
long
Size
Description
1 byte
2 bytes
4 bytes
8 bytes
float
double
boolean
char
4 bytes
8 bytes
1 bit
2 bytes
Stores whole numbers from -128 to 127
Stores whole numbers from -32,768 to 32,767
Stores whole numbers from -2,147,483,648 to 2,147,483,647
Stores whole numbers from -9,223,372,036,854,775,808 to
9,223,372,036,854,775,807
Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits
Stores fractional numbers. Sufficient for storing 15 decimal digits
Stores true or false values
Stores a single character/letter or ASCII values
Wrapper
Class
Byte
Short
Integer
Long
Float
Double
Boolean
Character
Non-Primitive Data Types
Non-primitive data types are called reference types because they refer to objects.
The main difference between primitive and non-primitive data types are:
Primitive types are predefined (already
defined) in Java.

Non-primitive types are created by
the programmer and is not defined by
Java (except for String).
Non-primitive types can be used to call
methods to perform certain operations,
while primitive types cannot.
 A primitive type has always a value,
while non-primitive types can be null.

A primitive type starts with a
lowercase letter, while non-primitive
types starts with an uppercase letter.


The size of a primitive type depends
on the data type, while non-primitive
types have all the same size.

Examples of non-primitive types
are Strings, Arrays, Classes, Interface, etc.

Use of Wrapper classes in Java
Java is an object-oriented programming language, so we need to deal with objects many times like
in Collections, Serialization, Synchronization, etc. Let us see the different scenarios, where we need to
use the wrapper classes.
o
Change the value in Method: Java supports only call by value. So, if we pass a primitive
value, it will not change the original value. But, if we convert the primitive value in an object, it
will change the original value.
o
Serialization: We need to convert the objects into streams to perform the serialization. If we
have a primitive value, we can convert it in objects through the wrapper classes.
o
Synchronization: Java synchronization works with objects in Multithreading.
o
java.util package: The java.util package provides the utility classes to deal with objects.
o
Collection Framework: Java collection framework works with objects only. All classes of the
collection framework (ArrayList, LinkedList, Vector, HashSet, LinkedHashSet, TreeSet,
PriorityQueue, ArrayDeque, etc.) deal with objects only.
The eight classes of the java.lang package are known as wrapper classes in Java.
public class out
{
public static void main()
{
//Converting int into Integer
int p=20;
Integer w=Integer.valueOf(p);//converting int into Integer explicitly
Integer x=p;//autoboxing, now compiler will write Integer.valueOf(a) internally
System.out.println(p+" "+w+" "+x);
//Converting Integer to int
Integer q=new Integer(3);
int y=q.intValue();//converting Integer to int explicitly
int z=q;//unboxing, now compiler will write a.intValue() internally
System.out.println(q+" "+y+" "+z);
}
}
The Java Runtime Environment (JRE) contains Java Virtual Machine, class libraries and browser plugins for applet and
application execution.
Q. What is a Servlet?
The servlet is a Java programming language class used to process client requests and generate dynamic web content.
Servlets are mostly used to process or store data submitted by an HTML form, provide dynamic content and manage
state information that does not exist in the stateless HTTP protocol.
JDBC is an abstraction layer that allows users to choose between databases. JDBC enables developers to write
database applications in Java without having to concern themselves with the underlying details of a particular
database.