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ARRAY

Single Array

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Course Learning Outcome :

1. Draw Diagram of PP and OOP

2. Identify Anatomy of Java Program

3. Identify Programming Style andDocumentation

4. Identify the Programming Errors

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Preview Question

1. Array are not objects in Java. [TRUE/FALSE]

2. The default length of an array is 10. [TRUE/FALSE]

3. Arrays are declared using the [] symbols. [TRUE/FALSE]

4. You can declare a 3 dimensional array. [TRUE/FALSE]5. An array with size of 10 will have a maximum index of 9.

[TRUE/FALSE]

6. An array can contain data of different types. [TRUE/FALSE]

7. Arrays of objects cannot be declare in Java. [TRUE/FALSE]8. Arrays can be extending by assigning it a new value.

[TRUE/FALSE]

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Objectives :

Write a program using single array :

Define an array

Declare and initialize an array

Pass array to methods

Return array to methods

Write program using single array

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Array Fundamental

An Array is a collection of similar type ofvariables having a common name.

Values in array are stored in consecutive

memory locations.

Two types of Arrays

One-dimensional array

Two-dimensional array

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One-deminsional Array

Will have a single row and can have any

number of columns.

Will have only one subscript. Subscriptrefers to the dimension of the array.

Example : int x[ ] =new int[3];

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Representation Array

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Declaration & Initialization

You need to declare an array before usingit in the program.

An array can be defined using differentdata types such as integer, double, float,char and so on.

However, all the values in an array mustbe of the same data type.

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Array Declaration

Syntax

[ ] =

new [Size of the array]

Example: int marks[ ] = new int[5];

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Array Initialization

Initialisation is the process of assigning values to the

array you have created.

Example

marks[0] = 95; marks[1] = 85;

marks[2] = 75;

marks[3] = 80;

marks[4] = 65;

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Array Initialization

Syntax :

[Array index] = Value;

The first element will always have the array index as 0.

Array index refers to the location of the values in an array.

For example:

marks[0]=95;

marks[1]=85;

marks[2]=75;

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Array Element

The representation of the array for the

example in the previous slide is as follows.

Here, 0, 1 and 2 are the index of the array, marks.

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Array Initialize

You can also initialise the array at the time of

declaration as shown in the following

example:

int marks[] = {95,85,75};When initialising an array, the values are

enclosed within curly brackets { }.

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Accessing Array Element

Using the array index you can access thearray elements.

To print the value of the second element inan array, the code will be:

System.out.println("The second

element:

+ marks[1]);

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Entering Data into an Array

When more number of values are to be stored in anarray, a for loop can be used.

The sample code shows how to use a forloop in anarray.

for(int i=0;i

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Reading Data from an Array

You can use a for loop with a single println

statement to print the values from an array.

for (int i=0;i

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Activity 1

Identify the array index of each element.

int ary[ ] = {2, 4, 6, 8}

a. 0, 1, 2, 3

b. 1, 2, 3, 4

c. 2, 4, 6, 8

d. 0, 2, 4, 6

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int scores[ ] = new int[25];

Identify the valid elements in the

following: Give reason for the same.

a. scores[0]

b. scores[1]

c. scores[-1]

d. scores[25]

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PASS & RETURN ARRAY TO METHODMULTIDIMENSIONAL ARRAY

To be continue