README.md

Questions & Solutions 💡

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Array and String

Java Arrays

Arrays are used to store multiple values in a single variable, instead of declaring separate variables for each value.

To declare an array, define the variable type with square brackets:

int[] myArr;

We have now declared a variable that holds an array of strings. To insert values to it, we can use an array literal - place the values in a comma-separated list, inside curly braces:

int[] myArr = {1, 2, 3};

Access Array Elements

Access an array element by pointing to its index number

Example:

String[] myFriends = {"Ahmad", "Abu", "Ali"};

System.out.println(myFriends[0]);

// Output: Ahmad

Array Length

To find out how many elements in an array just use length property:

String[] myFriends = {"Ahmad", "Abu", "Ali"};

System.out.println(myFriends.length);

// Output: 3

Print All Element in An Array

You can loop through the array elements with the for loop, and use the length property to specify how many times the loop should run.

String[] myFriends = {"Ahmad", "Abu", "Ali"};

for (int i = 0; i < myFriends.length; i++) {
    System.out.println(myFriends[i]);
}

// Output👇
// Ahmad
// Abu
// Ali

Empty Element in An Array

You can declare an array with empty element and initialize it later.

String[] favFood = new String[3]; // empty array

// initialize element in array
favFood[0] = "Karipap";
favFood[1] = "Nasi Lemak";
favFood[2] = "Ramen";

// print all elements in array
for (int i = 0; i < favFood.length; i++) {
    System.out.println(favFood[i]);
}

// Output👇
// Karipap
// Nasi Lemak
// Ramen

Java String charAt() Method

The charAt() method returns the character at the specified index in a string.

The index of the first character is 0, the second character is 1, and so on.

Example:

String text = "Mom";
char result = text.charAt(0);

System.out.println(result);

// Output: M

Java String length() method

• applicable for string objects
• method returns the number of characters present in the string
• suitable for string objects but not for arrays.

Example:

String text = "Mom";
int length = text.length();

System.out.println(length);

// Output: 3

charAt() and for Loop

Determine position in string:

String text = "Mom";

for (int i = 0; i < text.length(); i++) {
    System.out.print("At index " + i + ", the character is " + text.charAt(i));
}

// Output👇
// At index 0, the character is M
// At index 1, the character is 0
// At index 2, the character is m