Catie WelshFebruary 2, 2011
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Program 1 Due Today by 11:59pm today
Program 2 Assigned Today
Lab 2 Due Friday by 1:00pm
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Formatting decimals
Review Worksheet
If/Else statements
Boolean Expressions
import java.text.*;
DecimalFormat df = new DecimalFormat("0.00");
df.format(myVariable);
Example code on class website
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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);
} }
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Double myDouble = (1 / 2) * 5.0;
int i = 1 / 2;
0.5
O
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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;
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Check time;
if (time < 7am){
take bus;}
else //time >= 7am{
take subway;}
Reach school;
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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"); } } }
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Start
Prompt User for int
Is user input greater than 5?
Print: “small number”
Print: “bignumber”
YESNO
== Equal to
!= Not equal to
> Greater than
>= Greater than or equal to
< Less than
<= Less than or equal to
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True of False Example expressions
◦ 5 == 3;◦ Variable <= 6;◦ myInt != temp;
if (boolean expression){ statements }
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What if you need multiple expressions to be true
(expression) && (expression) && …◦ Expressions go in ( )
Will only be true if ALL statements are true
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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
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FIGURE 3.7 The Effect of the Boolean Operators && (and), || (or), and ! (not) on Boolean values
var1 = var2 (assignment statement)◦ Error!!!!!!!
var1 == var2 (boolean expression)
Do NOT use == to compare Strings◦ string1 == string2 //BAD
◦ string1.equals(string2); //GOOD
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SyntaxString.equals(Other_String)String.equalsIgnoreCase(Other_String)
You can use just an if statement
if (boolean expression){ (statements) }the rest of your code
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if (boolean expression){
if (boolean expression) { stuff goes here }else { more stuff }
}else
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Start
Prompt User for int
What is the integer?
Print: “hello” Print: “how may I help you”
inputInt > 1inputInt == 0
Print: “how are you”
inputInt == 1
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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");
} }
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Recitation
Bring Laptop
Bring Book
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