Basics

Question 1

Read Text File

Answer 1

can use BufferedReader, FileReader, or Scanner class

File file = new File("C:\\file_path\\test.txt"); 
Scanner sc = new Scanner(file); 

while (sc.hasNextLine())
System.out.println(sc.nextLine());

Question 2

Read input from console

Answer 2

can use Scanner class (java.util)

Scanner sc = new Scanner(System.in);
String username = scanner.nextLine();

Question 3

length vs length()

Answer 3

.length is a property of arrays

.length() is a method call for strings

Question 4

Write to File

Answer 4

Can use PrintWriter class (java.io)

File file = new File("C:/path/file.txt");
PrintWriter pw = new PrintWriter(file);
pw.println("hello")

Question 5

Binary Search

Answer 5

searches a sorted array by repeatedly dividing the search interval in half