5. java arrays

7/30/2019 5. JAVA Arrays

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Arrays, String and Other String class


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Module Objective

Arrays

Define an array.

Explain single - dimension array

Describe two dimension array

String

Other String class

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#1 - Array

Introduction to Arrays

Array declaration

Initializing Array Elements

Accessing Array Elements

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Introduction to Arrays

Special data store that can hold several items

of a single data type in contiguous memory

location.

All the elements within an array must belongto the same data type.

Arrays are zero indexed

An array with n elements is indexed from 0 to

n-1.

Array in Java is Object

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Array declaration

Declaring an array variable does not create an array!

You must use new to explicitly create the array instance

The default value of numeric array elements are set to zero, and

reference elements are set to null.

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Array dimension

The number of indexes associated with each element

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Initializing Array Elements

The elements of an array can be explicitly initialized

You can use a convenient shorthand

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Accessing Array Elements

Supply an integer index for each dimension

Indexes are zero-based

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Types of Arrays

Single - Dimensional Arrays

Multi - Dimensional Arrays (matrix, arrays of arrays)

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Single-Dimensional Arrays

Have only one dimension and is visually

represented as having several row but a single

column of data.

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Working with Single-Dimensional Arrays

Store elements :

Initialize individual array elements

Use Loop to initialize

Access elements:

Using Loop

for..each loop (JDK 1.5)

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Example of Working with Single-Dimensional Arrays

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Multidimensional Arrays, (matr ix, arrays o f arrays)

[ ] [ ] = new [ rows][cols]

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Working with Multidimensional Arrays

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#2 - String class

Describe String

Methods of String class

Describe String array and its use

Describe command line arguments in Java and its use

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String class

The String class represents character strings.

All string literals in Java programs, such as "abc", are

implemented as instances of String class.

Strings are constant

Values cannot be changed after they are created.

String objects are immutable they can be shared.

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Create a String Object

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Example of Using String class

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Common-used methods

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String Arrays

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String arguments

The parameter of the main() method represents the

command-line arguments.

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String Command Line Arguments

A Java application can accept any number of arguments from

the operating system command line.

The purpose is to specify the configuration information for the

application.

The parameter of the main() method is a String array that

represents the command-line arguments.

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Example of String Command Line Arguments

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#3 - Other String class

StringBuilder class

StringTokenizer class

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StringBuilderclass

A mutable sequence of characters.

String objects are immutable sequence of characters

Character or String can be inserted in the StringBuilder object

and they can also be appended at the end.

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Constructors ofStringBuilderclass

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Methods ofStringBuilderclass

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Example ofStringBuilderclass

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StringTokenizerclass

Allows an application to break a string into tokens

The set of delimiters (the characters that separate tokens) may

be specified either at creation time or on a per-token basis.

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Constructor ofStringTokenizerclass

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Method ofStringTokenizerclass

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Example of Using StringTokenizerclass

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Thats about all for today!

Array

String class

StringBuilder class

StringTokenizer class

Thank you al l for yo ur at tent ion and pat ient!

5. java arrays

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