Computer Organization I

Computer Science II

Intro Programming for Scientists

Package Title: Lab Questions Course Title: Big Java, Late Objects Chapter Number: 10 Graphical User Interfaces 1.1) Write a main program that displays a single frame with the title “My First Frame”. Set the size to 800 by 800. Make the frame visible. Answer: 1.2) Create a panel by using the JPanel class (i.e. create a JPanel object) and add it to the frame. Use Color.RED (a constant in the java.awt package) along with the setBackground() method of class JPanel , to set the color of the panel. Add a JButton and a JLabel to the panel (i.e. create JButton and JLabel objects) before adding the panel to the frame. Display the results. Answer: © John Wiley & Sons, Inc. All rights reserved. 1 1.3) The goal of this problem is to repackage most of the previous code above as a class that extends JFrame . Build a class called MyCustomFrame that extends JFrame . The class should contain instance variables for the button and the label , as well as constants for the frame width and height. The constructor method should call a private helper method, createComponents() , that instantiates the button, the label, and the panel. This helper method should also add the button and the label to the panel, and add the panel to the frame. After calling createComponents( , the constructor should set the size of the frame. Test your class with the viewer code below. import javax.swing.JFrame; public class MyCustomFrameViewer { public static void main(String[] args) { MyCustomFrame frame = new MyCustomFrame(); frame.setTitle("My first frame"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } } Answer: © John Wiley & Sons, Inc. All rights reserved. 2 1.4) Build a separate class called ClickListener that implements the ActionListener interface. Add an actionPerformed() method that prints the message “Button was clicked.” using System.out.println() . Inside the createComponents() helper method, create a ClickListener object and “attach” it to the button by calling the button’s addActionListener() method. Test the program by clicking the button. When the program is working correctly, convert the ClickListener class to an inner class inside class MyCustomFrame and test the program again. Answer: 1.5) Now create and add a JTextField object and a JTextArea object to the panel (i.e. create instance variables and then in the helper method createComponents() make the objects and add to the panel) Initialize the text in the JTextField object to an empty string (use the setText() method) and the JTextArea object text to “||” (use the setText() method). Modify the program in 1.4) above so that the text typed into the field by the user (which can be retrieved using the getText() method) is appended to the text in the text area component each time the user clicks the button. Google the class JTextField and JTextArea to see other methods available. For example, if the user enters “xxx” in the text field and clicks the button three times, the text area should contains “||xxx||xxx||xxx||”. The actionPerformed() method of the ClickListener class in 1.4) will need to be modified. Answer: © John Wiley & Sons, Inc. All rights reserved. 3

CPS | 209 | Computer Science II | lab | Package Title: Lab Questions C

6. Modular Programming and Functions - Copyright © Denis Hamelin - Ryerson University A void Function with No Arguments  A void function is a function that generates no results. /* a function definition */ void stars (void) { printf ("************************\n"); } ...  Inside the main program, the function would be called like this: stars ();  See the complete program at c.ihypress.ca/05.php. 6. Modular Programming and Functions - Copyright © Denis Hamelin - Ryerson University A void Function with One Argument  The stars function only displays the same number of stars every time.  What if I wanted to display a different number of stars that could be linked to a numerical value that I send to the function? All I would need to add is an argument to the function to specify the number of stars. See stars2 on the next slide. stars2 , like stars, has no result. When a function has no result, we declare its type as void . 6. Modular Programming and Functions - Copyright © Denis Hamelin - Ryerson University A void Function with One Argument /* a void function returns nothing */ void stars2 ( int n ) { int i; /* a loop displaying a star at each iteration */ for (i=1; i<=n; ++i) { printf ("*"); } /* change line after each series */ printf ("\n"); } The function would be called like this: stars2(x); See c.ihypress.ca/05.php 6. Modular Programming and Functions - Copyright © Denis Hamelin - Ryerson University A Function with One Result  A function that has a result will have a type (char, double, or int) and will finish with a return statement.  The result in the return statement must always match the type declared on top of the function.  See an example of a function calculating the factorial of a number on the next slide. 6. Modular Programming and Functions - Copyright © Denis Hamelin - Ryerson University A Function with One Result /* this function will return an integer */ int factorial ( int n ) { int i, product; product = 1; /* initialization */ /* computes n*n-1... */ for (i=n; i>1; i=i-1) { product = product * i; } /* the value that goes out */ return (product); } 6. Modular Programming and Functions - Copyright © Denis Hamelin - Ryerson University Things to Know  A function usually does not display anything on the screen (unless the function contains a printf statement).  Variables declared inside a function are unknown in the main program.  Variables of the main program are unknown inside the function.  The only way to send values from the main program to a function is through an argument.

CPS | 118 | Intro Programming for Scientists | lecture notes | 6. Modular Programming and Fun

CPS213 1 CPS213 – COMPUTER ORGANIZATION I LAB #5 S EQUENTIAL C IRCUIT D ESIGN All students are required to answer the questions individually and hand in a paper copy of their written answers to TA during the first hour of the lab. Then continue with the simulation of the circuits and show the simulation results to TA. Part A: You are to design a sequential circuit which has two inputs, X and an enable input, E . You will be using two JKFFs in your design. When the circuit is disabled, i.e., E = 0 :  There will be no change, that is, the circuit remains in the same state regardless of the value of X . When the circuit is enabled, i.e., E = 1 :  If X = 1 , the circuit goes through circular state transitions, 00 → 01 → 10 → 11 → 00 and repeats.  If X = 0, the circuit goes through the state transitions, 00 → 11 → 10 → 01 → 00 and repeats.

CPS | 213 | Computer Organization I | lecture notes | CPS213 1 CPS213 – COMPUTER ORG

Lecture 8: Arrays Little boxes, all the same Need for Arrays • So far, each variable has been a scalar , containing exactly one value at any given time • If your program needs to simultaneously store lots of data, it would need to have (and name) lots of scalar variables • Instead, arrays are a mechanism that allows us to store a large number of data elements under a single name • An array is a linear row of elements, each of which acts like an ordinary variable of the array element type • Each element has an integer index giving its position in the array, and is accessed with this index • Indices start from 0, so the last index is always one less than the size of the array Array Example #include <stdio.h> int main() { int i; int a[100]; /* An array with 100 integer elements. */ /* Fill the array. */ for(i = 0; i < 100; i++) { a[i] = i * i; } /* Access the element in position 30. */ printf("%d\n", a[30]); /* 900 */ return 0; } Arrays in Memory • In C, all arrays are homogeneous so that each element is of the same type given in the array declaration • This allows indexing to be a fast random access operation so that accessing the element in any location you need is equally fast, independent of the location index • Contrast this to linked lists , where to get to the 100:th element you have to step through the elements 1, ..., 99 • In practice, most functions access array elements in sequential order, since this is the simplest way to do things when every element needs to be accessed once, but the order in which this done doesn't matter • Only the array elements are stored in memory, but these bytes have no information about the array size or type Example: Sum of Elements /* The ﬁrst example function that gets an array as parameter. Since the array does not know its size, these functions must always receive this size as an additional int parameter. */ int sum(int a[], int n) { int sum = 0, i; for(i = 0; i < n; i++) { /* The indices of n-element array */ sum += a[i]; } return sum; } Example: Minimum Element double minimum(double[] a, int n) { double m = a[0]; int i; for(i = 1; i < n; i++) { if(a[i] < m) { m = a[i]; } } return m; } Example: Statistical Variance double variance(double a[], int n) { double sum = 0, sumSq = 0, avg, avgSq; int i; for(i = 0; i < n; i++) { sum += a[i]; sumSq += a[i] * a[i]; } avg = sum / n; avgSq = sumSq / n; return avgSq - (avg * avg); } Arrays as Function Parameters • When some function receives an array as a parameter, it really receives a pointer to the first element of this array, even though the array syntax pretends that this parameter is an array, not a pointer to one element • Indexing is actually a pointer operation, even though we think of it as an "array" operation • These pointers are passed by value  just like everything else in C, so the function and its caller share the same array through two different pointers • If the function modifies the actual array that was given to it as parameter, this change persists to the caller after the function execution has terminated

CPS | 118 | Intro Programming for Scientists | lecture notes | Lecture 8: Arrays Little boxes

CPS_125_Lecture_5_-_Loops.ppt-Lecture 5: Repetition While not learned

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