Java Arrays Declaration and Initialization

Declaring and Initializing Arrays

• In Java, an array is a fixed-size, homogeneous collection of elements.
• Arrays can be declared in two ways:
  • int[] myArray; (recommended)
  • int myArray[];
• Arrays can be initialized in two ways:
  • int[] myArray = new int[5]; (declare and initialize simultaneously)
  • int[] myArray; myArray = new int[5]; (declare and initialize separately)

Array Elements

• Array elements are accessed using their index (starting from 0).
• Elements can be assigned values using the assignment operator (=).
• Example: myArray[0] = 10;

Array Operations

• Length: The length of an array can be obtained using the length property.
• Copying: Arrays can be copied using the Arrays.copyOf() method.
• Sorting: Arrays can be sorted using the Arrays.sort() method.

Multidimensional Arrays

• Multidimensional arrays can be declared and initialized in a similar way to one-dimensional arrays.
• Example: int[][] my2DArray = new int[3][4];
• Elements can be accessed using multiple indices. Example: my2DArray[0][1] = 10;

Array Methods

• Arrays.toString(): Converts an array to a string representation.
• Arrays.equals(): Compares two arrays for equality.
• Arrays.fill(): Fills an array with a specified value.

Common Array Errors

• ArrayIndexOutOfBoundsException: Thrown when an array is accessed with an index that is out of bounds.
• NullPointerException: Thrown when an array is not initialized before use.

Declaring and Initializing Arrays

• In Java, an array is a fixed-size, homogeneous collection of elements.
• Arrays can be declared in two ways: int[] myArray; and int myArray[];.
• Arrays can be initialized in two ways: int[] myArray = new int; and int[] myArray; myArray = new int;.

Array Elements

• Array elements are accessed using their index (starting from 0).
• Elements can be assigned values using the assignment operator (=).
• Example: myArray = 10;.

Array Operations

Length

• The length of an array can be obtained using the length property.

Copying

• Arrays can be copied using the Arrays.copyOf() method.

Sorting

• Arrays can be sorted using the Arrays.sort() method.

Multidimensional Arrays

• Multidimensional arrays can be declared and initialized in a similar way to one-dimensional arrays.
• Example: int[][] my2DArray = new int;.
• Elements can be accessed using multiple indices.
• Example: my2DArray = 10;.

Array Methods

Arrays.toString()

• Converts an array to a string representation.

Arrays.equals()

• Compares two arrays for equality.

Arrays.fill()

• Fills an array with a specified value.

Common Array Errors

ArrayIndexOutOfBoundsException

• Thrown when an array is accessed with an index that is out of bounds.

NullPointerException

• Thrown when an array is not initialized before use.