(Dreaded) Quiz 2 Next Monday

Strings Revisited String Is a Type (Object) in JAVA Automatically imported in java.lang May Initialize or Assign with Double Quoted Values Can Add String to String with ‘+’ Operator CANNOT Compare using Equality Operators (uses .equals() method instead) Methods Available to Access single characters Get length of String Find a character or substring in String Convert to lower or upper case

Objects Objects: Types of Variables Made from Built-In Types Variables Can be Declared as an Object Type Objects Usually Have Methods/Functions Tied to Them Member functions Public functions Interface functions Methods String Is an Example of an Object Type StringVariable.length() Returns the Number of Characters in the String

Methods Also called Procedures, Functions Have Parenthesis (e.g., method() ) May be Passed Arguments, or Parameters Inside of Parenthesis Parameters are values to initialize new variables in method Parameters used to pass information to method

String Methods charAt(int index): return char at named index (starting at 0) equals(String str): return boolean indexOf(char): return int of first occurrence of char (index starts at 0) indexOf(String substr): return int of first occurrence of String substr length(): return int length of String substring(int start, int end): return String between start and end toLowerCase(), toUpperCase(): convert String

String myString = "My Dog Sandy",compareString; System.out.println("The fourth character is: " + myString.charAt(3)); if (myString.equals("my dog sandy")) System.out.println("Strings are equal"); else System.out.println("Strings are not equal"); compareString = myString + myString; System.out.println("Added strings are: " + compareString); Output: The fourth character is: D Strings are not equal Added strings are: My Dog SandyMy Dog Sandy

compareString = myString.toLowerCase(); System.out.println("String is: " + compareString); System.out.println("Char S is at location: " + myString.indexOf('S')); System.out.println("substring og is at location: " + myString.indexOf("og")); System.out.println("Length of string is: " + myString.length()); System.out.println("substring between location 3 and 5 is: " + myString.substring(3,5)); Output: String is: my dog sandy Char S is at location: 7 Substring og is at location: 4 Length of string is: 12 Substring between location 3 and 5 is: Do

import java.util.Scanner; public class MyProgram { public static void main( String [ ] args) Scanner scan = new Scanner(System.in); String lastname; boolean instructor = false; System.out.print(“Enter last name:”); lastname = scan.next(); if(lastname.equals(“hanrath”)) instructor = true; // privileged else instructor = false; // not privileged }

More on Input Input Failure Common *MUST* Be Part of Test Plan Pages 310-313 in Anderson Check Input for Type Desired If not, Notify User, and Get Rid of Line Use scan.hasNextInt(), scan.hasNextDouble(), scan.hasNextFloat()

Input Failure Example garbage = scan.nextLine(); import java.util.*; class InputFailureExample { public static void main(String[] args) int numE; String garbage; Scanner scan = new Scanner(System.in); System.out.print("Enter Integer: "); while (!scan.hasNextInt()) garbage = scan.nextLine(); System.out.println("Please try again."); } numE = scan.nextInt(); System.out.println("You entered: " + numE);

Know for Quiz 2 Everything through Exam 1 Loops: while, for, do-while switch-case Statement String Methods Input Failure Methods