This document provides an overview of Java utilities and collection classes. It discusses the Java Math class and methods for numeric operations. It also describes wrapper classes for primitive data types and lists the eight primitive types in Java. Finally, it provides an example of using the Collections class to sort, reverse, shuffle a list and check element frequencies.

1. JAVA UNIT 2(Part 1)
BY: SURBHI SAROHA

2. SYLLABUS
 Java Lang package
 Simple type wrappers
 Number,Double,float,byte,short,int,long,character,Boolean,process and void.
 The Maths class.
 Java Utility and Collection Classes.

3. Cont….
 Arrays as collections
 Algorithms
 Wrappers as implementations
 Extending the abstract implementation legacy collections
 Framework classes
 Traversing collections with enumeration’s

4. Java Lang package
 Provides classes that are fundamental to the design of the Java programming language.
 The most important classes are Object, which is the root of the class hierarchy, and Class, instances
of which represent classes at run time.
 Following are the Important Classes in Java.lang package :
 Boolean: The Boolean class wraps a value of the primitive type boolean in an object.
 Byte: The Byte class wraps a value of primitive type byte in an object.
 Character – Set 1, Set 2: The Character class wraps a value of the primitive type char in an object.
 Character.Subset: Instances of this class represent particular subsets of the Unicode character set.
 Character.UnicodeBlock: A family of character subsets representing the character blocks in the
Unicode specification.
 Class – Set 1, Set 2 : Instances of the class Class represent classes and interfaces in a running Java
application.

5. Cont…
 ClassLoader: A class loader is an object that is responsible for loading classes.
 ClassValue: Lazily associate a computed value with (potentially) every type.
 Compiler: The Compiler class is provided to support Java-to-native-code compilers and related
services.
 Double: The Double class wraps a value of the primitive type double in an object.
 Enum: This is the common base class of all Java language enumeration types.
 Float: The Float class wraps a value of primitive type float in an object.
 InheritableThreadLocal: This class extends ThreadLocal to provide inheritance of values from
parent thread to child thread: when a child thread is created, the child receives initial values for all
inheritable thread-local variables for which the parent has values.
 Integer :The Integer class wraps a value of the primitive type int in an object.
 Long: The Long class wraps a value of the primitive type long in an object.

6. Cont…
 Math – Set 1, Set 2: The class Math contains methods for performing basic
numeric operations such as the elementary exponential, logarithm, square root,
and trigonometric functions.
 Number: The abstract class Number is the superclass of classes BigDecimal,
BigInteger, Byte, Double, Float, Integer, Long, and Short.
 Object: Class Object is the root of the class hierarchy.
 Package: Package objects contain version information about the implementation
and specification of a Java package.
 Process: The ProcessBuilder.start() and Runtime.exec methods create a native
process and return an instance of a subclass of Process that can be used to control
the process and obtain information about it.
 ProcessBuilder: This class is used to create operating system processes.

7. Cont…
 Math – Set 1, Set 2: The class Math contains methods for performing basic
numeric operations such as the elementary exponential, logarithm, square root,
and trigonometric functions.
 Number: The abstract class Number is the superclass of classes BigDecimal,
BigInteger, Byte, Double, Float, Integer, Long, and Short.
 Object: Class Object is the root of the class hierarchy.
 Package: Package objects contain version information about the implementation
and specification of a Java package.
 Process: The ProcessBuilder.start() and Runtime.exec methods create a native
process and return an instance of a subclass of Process that can be used to control
the process and obtain information about it.
 ProcessBuilder: This class is used to create operating system processes.

8. Cont…
 StringBuffer: A thread-safe, mutable sequence of characters.
 StringBuilder: A mutable sequence of characters.
 System: The System class contains several useful class fields and methods.
 Thread: A thread is a thread of execution in a program.
 ThreadGroup: A thread group represents a set of threads.
 ThreadLocal: This class provides thread-local variables.
 Throwable: The Throwable class is the superclass of all errors and exceptions in the
Java language.
 Void: The Void class is an uninstantiable placeholder class to hold a reference to
the Class object representing the Java keyword void.

9. Simple type wrappers
 A Wrapper class is a class whose object wraps or contains primitive data types.
 When we create an object to a wrapper class, it contains a field and in this field, we
can store primitive data types.
 In other words, we can wrap a primitive value into a wrapper class object.
 Need of Wrapper Classes
 They convert primitive data types into objects. Objects are needed if we wish to
modify the arguments passed into a method (because primitive types are passed
by value).
 The classes in java.util package handles only objects and hence wrapper classes
help in this case also.

10. Cont….
 Data structures in the Collection framework, such as ArrayList and Vector, store
only objects (reference types) and not primitive types.
 An object is needed to support synchronization in multithreading.
 Primitive Data types and their Corresponding Wrapper class

11. Number,Double,float,byte,short,int,
long,character,Boolean,process and void.
 int myNum = 5; // Integer (whole number)
 float myFloatNum = 5.99f; // Floating point number
 char myLetter = 'D'; // Character
 boolean myBool = true; // Boolean
 String myText = "Hello"; // String
 Data types are divided into two groups:
 Primitive data types - includes byte, short, int, long, float, double, boolean and char
 Non-primitive data types - such as String, Arrays and Classes

12. There are eight primitive data types in Java:
 Data Type Size Description
 byte 1 byte Stores whole numbers from -128 to 127
 short 2 bytes Stores whole numbers from -32,768 to 32,767
 int 4 bytes Stores whole numbers from -2,147,483,648 to 2,147,483,647
 long 8 bytes Stores whole numbers from -9,223,372,036,854,775,808 to
9,223,372,036,854,775,807
 float 4 bytes Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits
 double 8 bytes Stores fractional numbers. Sufficient for storing 15 decimal digits
 boolean 1 bit Stores true or false values
 char 2 bytes Stores a single character/letter or ASCII values

13. The Maths class
 Java Math class provides several methods to work on math calculations like min(), max(), avg(), sin(),
cos(), tan(), round(), ceil(), floor(), abs() etc.
 Example 1
 public class JavaMathExample1
 {
 public static void main(String[] args)
 {
 double x = 28;
 double y = 4;

 // return the maximum of two numbers
 System.out.println("Maximum number of x and y is: " +Math.max(x, y));

14. Cont…
 // return the square root of y
 System.out.println("Square root of y is: " + Math.sqrt(y));

 //returns 28 power of 4 i.e. 28*28*28*28
 System.out.println("Power of x and y is: " + Math.pow(x, y));

 // return the logarithm of given value
 System.out.println("Logarithm of x is: " + Math.log(x));
 System.out.println("Logarithm of y is: " + Math.log(y));

 // return the logarithm of given value when base is 10
 System.out.println("log10 of x is: " + Math.log10(x));
 System.out.println("log10 of y is: " + Math.log10(y));

15. Cont….
 // return the log of x + 1
 System.out.println("log1p of x is: " +Math.log1p(x));

 // return a power of 2
 System.out.println("exp of a is: " +Math.exp(x));

 // return (a power of 2)-1
 System.out.println("expm1 of a is: " +Math.expm1(x));
 }
 }

16. Java Utility and Collection Classes.
 Collections class in java is a useful utility class to work with collections in java.
 The java.util.Collections class directly extends the Object class and exclusively
consists of the static methods that operate on Collections or return them.
 Collections Class in java
 Collections class contains polymorphic algorithms that operate on collections and
“wrappers” — which return a new collection backed by a specified collection. It is a
member of Java Collections Framework.
 Collections class fields
 Collections class contains 3 fields: EMPTY_LIST, EMPTY_SET, EMPTY_MAP, which can
be used to get immutable empty List, Map and Set respectively.

17. Example
 package utility;
 import java.util.Collections;
 import java.util.ArrayList;
 import java.util.List;
 public class CollectionsDemo {
 public static void main(String[] args) {
 List<String>student<String>List = new ArrayList();
 studentList.add("Neeraj");
 studentList.add("Mahesh");
 studentList.add("Armaan");


18. Cont….
 studentList.add("Preeti");
 studentList.add("Sanjay");
 studentList.add("Neeraj");
 studentList.add("Zahir");
 System.out.println("Original List " + studentList);
 Collections.sort(studentList);
 System.out.println("Sorted alphabetically List " + studentList);
 Collections.reverse(studentList);
 }

19. Cont….
 System.out.println("Reverse List " + studentList);
 Collections.shuffle(studentList);
 System.out.println("Shuffled List " + studentList);
 System.out.println("Checking occurance of Neeraj: "
 + Collections.frequency(studentList, "Neeraj"));

20. THANK YOU 