Comprog 3

• Array in Java


  An object used to store elements of the same data type in contiguous memory locations
• Characteristics of a single-dimensional array

  • It can store elements of the same data type
  • It represents a list of variables of the same data type
  • Elements are accessed by specifying their index
• Declare a single-dimensional array in Java


  int[] arrayName;
• Declare and initialize a single-dimensional array in Java


  int[] numbers = new int[5];
• Two-dimensional array


  An array of arrays where data is organized into rows and columns
• Print elements of an array using a Java for loop


  for (int i = 0; i < array.length; i++) { System.out.println(array[i]); }
• Java for-each loop


  Allows you to traverse an array without explicitly using indices
• Arrays.toString() method


  Converts an array to a string representation
• Variables in Java


  Containers for storing data values
• Local variables


  Declared inside a method, constructor, or block of code
• Instance variables


  Can be accessed from anywhere within the class
• Difference between local and global variables


  Local variables are accessible only within the block of code in which they are declared, while global variables can be accessed from anywhere within the class
• abs() method in Java Math class


  Returns the absolute value of a number
• sqrt() method in Java Math class


  Returns the square root of a number
• max() method in Java Math class


  Returns the larger of two values
• String literal


  A sequence of characters enclosed in double quotes
• Where string literals are stored

  String pool
• length() method for strings


  Used to obtain the length of a string
• Java Stream API


  Processes collections of objects with functional-style operations
• Iterator interface


  Used to iterate over elements in a collection
• Arrays.equals() method


  Compares two arrays for equality
• Arrays.asList() method


  Converts an array to a list
• Arrays.sort() method


  Sorts the elements of an array
• Java for-each loop


  Allows you to iterate over elements in an array without using indices
• log() method in Java Math class


  Calculates the natural logarithm of a number
• round() method in Java Math class


  Rounds a floating-point value to the nearest integer
• sin(), cos(), tan() methods in Java Math class

  Calculate the trigonometric sine, cosine, and tangent of an angle
• substring(int i, int j) method for strings

  Returns the substring from the specified start index to the end index - 1
• toLowerCase() method for strings


  Converts all characters in the string to lowercase
• replace(char oldChar, char newChar) method for strings


  Replaces all occurrences of a specified character with another character in a string
• Difference between string literal and string object


  A string literal is stored in the string pool, while a string object is stored in the heap memory
• charAt(int i)


  Returns the character at the specified index position in this string
• substring(int i)


  Returns a new string that is a substring of this string
• indexOf(String s)


  Returns the index within this string of the first occurrence of the specified substring
• String literal


  Stored in the string pool
• String object


  Stored in the heap memory
• String literal


  Immutable
• String object


  Mutable
• String literals are created using double quotes, while string objects are created using the new keyword</b>
• String literals have a fixed size, while string objects can dynamically resize