Arrays

Question 1

what are Array?

Answer 1

A collection of variable of the same data type.
1. An Array in Java is an object
2. An have a fixed size.
3. An array variable referenced a group of data.

Question 2

what null in Java?

Answer 2

The value of the object that reference noting.

string name: // null

Question 3

how do you create Array?

Answer 3

1. String[] name; // null
2. String[] name = new String[4];
   // create 4 array in the
   memory

Question 4

what are the default value give to Array when created.

Answer 4

1. 0 for numeric data types
2. null for reference types
3. false for boolean types
   4./u0000 for char types

Question 5

How do you access Array elements?

Answer 5

use brackets and indices
Example:
int[] numbers = new int[4]
numbers[0] = 4;
// this assign 4 to the first element in the array

Question 6

How do we print Array?

Answer 6

To print array there are two ways:
1.we use a for loop to print the array
2. we use a for each loop to print the array.

Question 7

what are Anonymous Array?

Answer 7

An array without a variable referencing it.
new Scanner(System.in) .nextline();

Question 8

How do we return array from method?

Answer 8

int[] numbers = getNumber();
printArray(numbers);
// we are returning an array form the method get numbers into the main method

public static in[] getNumber(){
return int[] {2,3,3,5,6};
}

Question 8

How do pass Array to method

Answer 8

Array are passed by reference

Question 8

Exceeding array bounds

Answer 8

The indices must be between 0 and length -1.
if you exceed the index of an array you will have an exception message printed to you on the console.

Question 9

what is the Array class in java?

Answer 9

A class that contains some static methods that are used with arrays

Question 10

what is the method used to sort array?

Answer 10

1. this method sort the whole Array
   The sort(); method is used to sort Array in Java.
   example: Array.sort(string);
2. this method sort part of the array.
   sort( Array, fromindex, to index);

Question 11

what is the method use to search Array?

Answer 11

1. this method is use to search
   array: binarySearch();

example: binarySearch(numbers,4);
// we are searching for the value of 4 from an array created in the memory.

Question 12

what is the method used to compare array?

Answer 12

we use the equal(); method to compare array in java
example:
Array.equal(number1, number2);

Question 13

How do we fill Array with value?

Answer 13

we fill array using the fill method.
fill(array, value);
example: fill(number, 4)

fill(array, fromindex, to index, value);

Question 14

How do we print Array?

Answer 14

1. we print array using the toString() method in the array class.
   example: Array.toString(numbers);

Question 15

what is variable length Argument lists?

Answer 15

a variable number of arguments can be passed to a method.
example: sum(1,2,);
sum(1,3,8);
sum(1,2,3,4);

Question 16

how do you pass a variable number of arguments to a method

Question 17

What are 2D Array?

Answer 17

A two dimensional Array is a one dimensional array in which each element is another one dimensional array.
example: int[] [] numbers = new int[4];

Question 18

what are ragged Arrays?

Answer 18

A 2D array with rows of different length.
{2,3,4}
{2,3,4,5}
{2,3,4,5,6}

Question 19

In the 2D array the first dimension is what?

Answer 19

the first dimension is numbers of row.

Question 20

how do we create a 2D Array?

Answer 20

int[][] numbers = new int[4][4];
int[][] numbers;
numbers[4][4];

Question 21

Accessing 2D Array Element

Answer 21

the first row index is 0 and the second row index is one(1)
2. we can access the element using the index of row and column.
3. numbers[indexofrow][indexofcolumn]

Question 22

How do we print 2D Array

Answer 22

1. we can print 2D Array by accessing the element by it index and printing it.
   example: numbers[0][0]
   // this print the first element in the first row of the 2D arraya. print Row by Row
   we can use a for loop to print row by row.
   example: for( int i = 0; i < 3(amount of row); i++)
   for(int j = 0; j < 4(amount of colum) j++);
   System.out.println(number[i][j]) // print all the element in the array. i represent the row and j represent the column
   b. column by Column
   we also use a for loop for this
   but i will be the column and j will be the row.

Question 23

what are the other method to print the string representation of array?

Answer 23

deepToString(); method is use to print the string represenstation of an 2D array