Java Tutorial #19

Introduction to Multidimensional Arrays
Java also allows two dimensional and multidimensional size arrays. And the simplest form of multidimensional array is the two dimensional array. Its general equation is:

Type array_name[1^st Index][2^nd Index] = { {a, b, c } , {d, e, f} };

Where: 1^st index is the number of row, 2^nd index is the number of column. a, b and c are the elements of the first row (which is row 0) and d, e and f are the elements of the second row (which is row1).

Note: All index start counting from 0.

Ex.

int input[ ] [ ] = { {1, 2, 3} , {4, 5, 6} };

Just look at the table below.

Array “input”	Column 0	Column 1	Column 2
Row 0	1	2	3
Row 1	4	5	6

The table represents the array input. The array “input” is a two-dimensional array. It composed of many elements found on a separate row and column. Unlike the single dimensional array which contains a columns only. The array initializer above is also the same to this one.

input[0] [0] = 1;                                                input[1] [0] = 4;

input[0] [1] = 2;                                                input[1] [1] = 5;

input[0] [2] = 3;                                                input[1] [2] = 6;

Just look at the table, the values above and the array initializer. You will get it by looking to those things.

Java Tutorial #18

Java’s enhanced for Loop
Java developed a special for loop for array application is it is called the enhanced for loop. The enhanced for loop will take two arguments unlike the traditional for loop which is taking three arguments. Java developed a special for loop for array application. Its general equation is:

for (type identifier: name_array)

Where: type is the data type, identifier is a variable that will store value in the array every time the loop is going through. For example

input[ ] = {6, 2, 3, 4, 5};

identifier will hold 6, then it will hold 2, and later it will hold 3. Everytime the loop is going through, it hold the value in the array one at a time. For example

for (int var: input);

var is the identifier of the array input.

Consider this program:

First, I declare an array named “"input" and I declare a variable then initialize it to zero.

"sum" will hold the value each time the values are added. I created an enhanced for loop. I use "var" to hold each element in the array and I included the name of the array. The formula will add 0 to the first value in the array, then it will add the outcome of the previous operation to the second value in the array. Later, It will add the outcome of the previous operation to the third value until it reach the last value in the array. At last, it will display the sum of all the values in the array. This is the output.

Java Tutorial #17

Application of Array in Tables
Consider this program.

In the example, I declare a String array (Array Name and Nick). I created a loop that will automatically go to each item in the array. This will count how many items in each array.

Here's How:  First, create a variable that will serve as the index. Initialize its value to 0. Second, set a condition that this value is greater than the size of the array. The keyword .length is a special java function reserve for the counting the elements inside an array (initializer).

Now, index=0, and it is greater than the elements in the array "Name". The next step is to increment the variable index. So, index=0, will count from 0 to “how many elements in the array "Name", and will increment 1 to its value (the values will increase one value).

The next step is outputting the index (plus a tab space) and the value of the array. Since the variable "index" is created to count how many elements in the array are, we can now use it as index  of the array "Name". What the for loop does is.. it will go through each elements of the array (it will take all of the elements inside that array). IT WILL OUTPUT THIS ONE. I UNDERSTAND YOU IF YOU DON'T UNDERSTAND THIS ONE. I THINK THIS IS ONE OF THE DIFFICULT PARTS OF JAVA AND ALSO THE C++. AND I PERSONALLY HATED THIS PART. SO, I DON'T SPEND MORE WORDINGS TO IT. I PERSONALLY UNDERSTAND IT. I TRIED MY BEST TO EXPLAIN IT FOR SOME DUMMY OUT THERE.

Java Tutorial #16

Introduction to Arrays
Array - it is a variable that contains many values. It can store values with the same data type.

-It is a collection of variables of the same type that are referenced by a common name.

Syntax

Type var_name [ ] = new Type[Size];

Where: “var_name” is the name of the array, Type is the data type, and Size is how many elements this array will hold.

-All arrays have 0 as the index of their first element. So, If you declaring

int input[ ] = new int [9];

-You are declaring an integer array that has 10 elements, input[0] through                                input[9].  

Assigning values to each items in the array

The first way of assigning values to each array's item is by writing the values one by one. You can assign a value to each of the elements by writing this.

var_name[index] = some_value;

For example,

input[0] = 67;

This will assign “67 as the value of the first element in the array. (NOTE: THE COMPUTER STARTS COUNTING FROM 0 TO SOME_VALUE.) The subscript “0 is called an index and “input is the name of the array. The index is simply a system of numbering items in the arrays content. So, If you like to assign a value in the second element, you will write 1 as index.

The second way of assigning is called “Array Initializer”. This will initialize a value to each element without typing the array name and the index value. By writing this,

int input[ ] = {2, 7, 8, 93, 83};

You don't have to spend much of your time to declare the array's size and index. This will assign“2 as the 0 element and “83 as the 4 element. Initializers will automatically counts how many element you put in the array and this will also automatically assign an index to each of the element. “2 is input[0], “7 is input[1] and so on.

Dislaying Array’s Element

TO DISPLAY: 

Simply call out the println function and concate it with some string.

Just write the name of the array and the index of the element in the array.

 Consider this Example. These programs will use both of the ways of displaying Array's Element.

By using the first way:

By using the second way:

The output: