1. Catie Welsh February 2, 2011 1

2.  Program 1 Due Today by 11:59pm today  Program 2 Assigned Today  Lab 2 Due Friday by 1:00pm 2

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4. 4  Formatting decimals  Review Worksheet  If/Else statements  Boolean Expressions

5.  import java.text.*;  DecimalFormat df = new DecimalFormat("0.00");  df.format(myVariable);  Example code on class website 5

6. public class MyProgram { public static void main(String[] args) { String myString = “This is a string”; int len = myString.length(); System.out.print(“the length is “ + len); String shortString = myString.substring(10); } 6

7.  Double myDouble = (1 / 2) * 5.0;  int i = 1 / 2; 0.5 O 7

8.  Suppose that mary is an object of class Person, and suppose that increaseAge is a method of class Person that uses one argument, an integer. Write the invocation of the method increaseAge for the object mary using the argument 5. mary.increaseAge(5); Person mary = new Person; 8

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10. Check time; if (time < 7am) { take bus; } else //time >= 7am { take subway; } Reach school; 10

11. import java.util.*; public class FlowChart { public static void main(String[] args) { System.out.println("Give me an integer:"); Scanner keyboard = new Scanner(System.in); int inputInt = keyboard.nextInt(); if( inputInt > 5) { System.out.println("Big number"); } else { System.out.println("Small number"); } } } 11 Start Prompt User for int Is user input greater than 5? Print: “small number” Print: “big number” YES NO

12. ==Equal to !=Not equal to >Greater than >=Greater than or equal to <Less than <=Less than or equal to 12

13.  True of False  Example expressions ◦ 5 == 3; ◦ Variable <= 6; ◦ myInt != temp;  if (boolean expression) {statements } 13

14.  What if you need multiple expressions to be true  (expression) && (expression) && … ◦ Expressions go in ( )  Will only be true if ALL statements are true 14

15.  What if you need ONE expression to be true out of many expressions  (expression) || (expression) || … ◦ Expressions go in ( )  Will be true if ONE expression is true 15

16.  FIGURE 3.7 The Effect of the Boolean Operators && (and), || (or), and ! (not) on Boolean values

17.  var1 = var2 (assignment statement) ◦ Error!!!!!!!  var1 == var2 (boolean expression)  Do NOT use == to compare Strings ◦ string1 == string2 //BAD ◦ string1.equals(string2); //GOOD 17

18.  Syntax String.equals(Other_String) String.equalsIgnoreCase(Other_String)

19.  You can use just an if statement  if (boolean expression) { (statements) } the rest of your code 19

20. if (boolean expression) { if (boolean expression) { stuff goes here } else { more stuff } } else 20

21. Start Prompt User for int What is the integer? Print: “hello” Print: “how may I help you” inputInt > 1 inputInt == 0 Print: “how are you” inputInt == 1 21

22. import java.util.*; public class FlowChart { public static void main(String[] args) { System.out.println("Give me an integer:"); Scanner keyboard = new Scanner(System.in); int inputInt = keyboard.nextInt(); if ( inputInt == 0) System.out.println(”hello"); else if ( inputInt == 1) System.out.println(”how are you"); else System.out.println(”how may I help you"); } } 22

23.  Recitation  Bring Laptop  Bring Book 23