1. (Dreaded) Quiz 2
Next Monday

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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 }

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

10. 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);

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