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1323Agenda3 HW int number = 716; System.out.println(“The number is “ + “number”); Valid variable name? two_shoes Flowchart symbols and clarity. “Single.

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Presentation on theme: "1323Agenda3 HW int number = 716; System.out.println(“The number is “ + “number”); Valid variable name? two_shoes Flowchart symbols and clarity. “Single."— Presentation transcript:

1 1323Agenda3 HW int number = 716; System.out.println(“The number is “ + “number”); Valid variable name? two_shoes Flowchart symbols and clarity. “Single entry point, single exit” for I/O, computation/process Lab2 Good work – Continue to bring the kitchen sink to lab. I’m hiring 3 new people: 1 to convert code to flowchart (like last class quiz) 1 to convert flowcharts to code 1 to develop flowcharts

2 String objects String fname = “Jill”; How ‘long’ is fname? How many characters in fname? Sure, you just counted them – 4

3 String objects String fname = “Jill”; How ‘long’ is fname? How many characters in fname? Sure, you just counted them – 4 String someLets = “asfgiopawrth8[w gae[gnklasdfga[r 9awe[rgklr 890S_yS nawoguS IS GiOPGIOS{G jIG imn{ Gjio[ SGJi{SiSgj()S{ GJ9S gj[ adfg9pa GUUV(_ “; How long is someLets?

4 String objects String someLets = “asfgiopawrth8[w gae[gnklasdfga[r 9awe[rgklr 890S_yS nawoguS IS GiOPGIOS{G jIG imn{ Gjio[ SGJi{SiSgj()S{ GJ9S gj[ adfg9pa GUUV(_ “; How long is someLets? Good news – java gives us a tool that tells us. A method called ‘length’. How do we use it? int len = 0; len = someLets.length(); That looks something like num2Sqrt = Math.sqrt(num2); Yes, they are both ‘Method calls”.

5 Review To obtain user input from the terminal: 1 import java.util.Scanner; 2 Scanner console = new Scanner(System.in); 3 gpa = console.nextDouble ( ); Example: (after having 1 and 2 in your program:) double num1 = 0; System.out.println (“Please enter a number: “); num1 = console.nextDouble( ):

6 Sample Flowchart

7 Logic error, symbol error!

8 if – else construct if (newRate > oldRate) { cost = price * newRate; System.out.println(“New cost is “ + cost); } else { cost = price * oldRate; System.out.println(“No change to cost. Cost is “ + cost); } Note the use of the concatenation operator + What is the “TRUE Block” “FALSE Block” Note the indention of ‘subservient code’

9 Note that an if does not require an else. if ( code > oldCode) { System.out.println(“Code has changed. New code: “ + code); } System.out.println (“Hello Joe”); Now I’ll put some examples on the board to try to trick you

10 Pick a num1: if (num1 > 5) System.out.println(“Joe”); else { System.out.println(“Sarah”); System.out.println(“Alice”); num1 = num1 + 1; } System.out.println(“Henry”); // if (num1 > 5) System.out.println(“Joe”); else System.out.println(“Sarah”); System.out.println(“Alice”); num1 = num1 + 1; System.out.println(“Henry”);

11 Pick a num1: if (num1 > 5) System.out.println(“Joe”); System.out.println(“Alice”); else { System.out.println(“Sarah”); System.out.println(“Alice”); num1 = num1 + 1; } System.out.println(“Henry”); // if (num1 > 5) System.out.println(“Joe”); else System.out.println(“Sarah”); System.out.println(“Alice”); num1 = num1 + 1; System.out.println(“Henry”);

12 Subservient code. A standard practice is to indent subservient code consistently. At Dell, it is 2 spaces, Google, 4 spaces if (num1 > 5) { num1 = num1 * 7; num2 = 9; } else { num2 = 0; } Notes: { on line by itself else on line by itself

13 Nested if statements if (num1 > 5) { if (num2 == 4) { num1 = num1 * 7; num2 = 9; } else num1 = 5; } else { num2 = 0; }

14 Let’s work on lab 3 Note: Answering questions in the lab: Read the lab at least 5 times. Complete flowcharts for the program that you are working on. (it doesn’t have to be perfect, but it does have to be complete) What is a “workbench box” in a flowchart? (think chocolate chip cookies) Every method has its own flowchart. Every program and system have their own Block Diagram

15 lab 3 seuCalculator has one method - main seuController will have several methods, main, calculator, analyzeSentence, dieRoll and moneyBags main is a ‘controller’ method – s/he will just tell other people what to do. The calculator method will end up being your seuCalculator program logic So we will put several methods in one class?

16 lab 3 How will we do that? First things first – we already have a flowchart for calculator, so we just need a flowchart for seuController main method Here we go ----

17 lab 3 How will we do that? Did we get here on Tuesday? If so, roll on.

18 int num1 = 3; System.out.println(“Hello “ + num1 + “ cats”); System.out.print(“well, “); System.out.println(“well.”); System.out.println(“So, let’s go \n” + “party!”); Pop a new line - - how?, automatic?

19 P lease E xcuse M y D ear A unt S ally Order of operations (3*5 + 7) * 3/7 – 2 You can never have too many parentheses

20 Operators ==Equality operator (for primitive data types) != > >= < <= ||or &&and

21 Logical expression – an expression that is true or false universally Truth Table 3 > 5 || today is Monday ABA||BA&&B!AA&&!B TTTTFF TFTFFT FTTFTF FFFFTF

22 Random numbers in java - book page 188 (we will just use nextInt(xx) there are others) 1. import java.util.Random; 2. Random gener = new Random(); 3. int num1 = 0; Ex: num1 = gener.nextInt(7); // integer 0, 1, 2, 3, 4, 5, 6 Ex: num1 = gener.nextInt(20); // integer 0, 1, 2, …, 19 Ex: num1 = gener.nextInt(2); // ?

23 Ex: random integer between 4 and 13 we need rnum to be 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 so 10 numbers. Note: 13 – 4 is 9 we need = 10 How do we get 10 random numbers? nextInt(10) yes, but 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 But we want one of the 10 numbers 4, 5, 6, …, 13 Well, just add 4 to each of these numbers and …. So: rnum = gener.nextInt(10) + 4; does the job Ex: generate a random integer between -3 and 3


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