String & Scanner Class Methods Flashcards

Study Notes

String Class Methods

Defining a New String:
- String variable can be initialized using new String("text here") or simply String variable = "text here";
length() Method:
- Returns the number of characters in the string as an integer.
charAt(int index) Method:
- Retrieves the character at a specified index in the string and returns it as a char.
- Requires an integer parameter for the index.
substring(int beginIndex, int endIndex) Method:
- Returns a substring defined by a starting index (inclusive) and an ending index (exclusive).
- Can also create a substring from the starting index to the end of the string with substring(int beginIndex).
indexOf(int ch, int fromIndex) Method:
- Finds the index of the first occurrence of a specified character, starting the search from a given index.
- Can also be used to search for a substring.
compareTo(String str) & compareToIgnoreCase(String str):
- Compares the original string with another string alphabetically.
- Returns a negative integer if the original comes before the other string, positive if it comes after, and zero if both are identical.
equals(String str) & equalsIgnoreCase(String str):
- Checks for equality between two strings.
- Returns true if the strings are identical, otherwise returns false.
- Requires a parameter that is the string to compare.

Scanner Class

Purpose:
- Facilitates easy input reading methods for various data types.
Defining Scanner Object:
- Instantiate using Scanner reader = new Scanner(System.in); to read input from the console.
Importing Scanner Class:
- Include import java.util.Scanner; before the class declaration to enable usage of the Scanner class.
nextInt() Method:
- Allows the user to input an integer value from the console and returns it as an int.
nextDouble() Method:
- Enables the user to input a double value, returning it as a double.
next() Method:
- Reads a single word input from the console and returns it as a String.
nextLine() Method:
- Retrieves an entire line of input from the console, including spaces, until a newline character is encountered.

Math Class

Overview:
- Contains static methods for basic numeric operations.
- Methods are callable on the class itself without needing to create an instance.
Math.PI:
- Constant that represents the value of π (pi) and is accessible without needing an object.
sqrt() Method:
- Computes the square root of a specified double value and returns it as a double.
- Requires a double parameter for the input value.

Description

Test your knowledge on the String and Scanner class methods with these flashcards. Each card covers important methods and definitions, ensuring you understand the fundamentals of string manipulation in programming.