the phrase "exceptional event." Definition: An exception is an event that occurs during the execution of a program that disrupts the normal flow of instructions during the execution of a program. The Causes of Exceptions An abnormal execution condition was synchronously detected by a Java Virtual Machine. Such conditions arise because: 1. evaluation of an expression violates the normal semantics of the Java language, such as an integer divide by zero, as summarized in. 2. An error occurs in loading or linking part of the Java program . 3. Some limitation a resource is exceeded, such as using too much memory.
exception occurred either because: 1. the method stop of class Thread was invoked. 2. an internal error has occurred in the virtual machine. InternalError: An internal error has occurred in a Java Virtual Machine, because of a fault in the software implementing the virtual machine, a fault in the underlying host system software, or a fault in the hardware. This error is delivered asynchronously when it is detected, and may occur at any point in a Java program. OutOfMemoryError: A Java Virtual Machine has run out of either virtual or physical memory, and the automatic storage manager wasn't able to reclaim enough memory to satisfy an object creation request. StackOverflowError: A Java Virtual Machine has run out of stack space for a thread, typically because the thread is doing an unbounded number of recursive invocations due to a fault in the executing program. UnknownError: An exception or error has occurred but, for some reason, a Java Virtual Machine is unable to report the actual exception or error.
known as exceptions to help programs report and handle errors. When an error occurs, the program throws an exception. What does this mean? It means that the normal flow of the program is interrupted and that the runtime environment attempts to find an exception handler—a block of code that can handle a particular type of error. The exception handler can attempt to recover from the error or, if it determines that the error is unrecoverable, provide a gentle exit from the program. Three statements play a part in handling exceptions: The try statement identifies a block of statements within which an exception might be thrown. The catch statement must be associated with a try statement and identifies a block of statements that can handle a particular type of exception. The statements are executed if an exception of a particular type occurs within the try block. The finally statement must be associated with a try statement and identifies a block of statements that are executed regardless of whether or not an error occurs within the try block.
1.Import the fallowing import jdg.ch05.KeyboardInput; / /provided by SA import java.lang.System; import java.lang.Exception; import java.io.*; 2. Create the fallowing static KeyboardInput kbd = new KeyboardInput(System.in); static int sumTotal=0; 3. Create a new user Exception that would handle if the module would accept a new entry to be added to sumTotal variable. Screen Display Do You want to add another number (y/n): Answer y add a new number n exit module.
String strLine 4.1.2 int numToCount; 4.2 processUserInput() handles the fallowing task 4.2.1. Accept Data coming from keyboard. 4.2.2. Add input value to sumTotal. If entered value is numeric. 4.2.3. Display running total of sumTotal. 4.2.4. If value entered not numeric do necessary exception handling. Insert the fallowing lines of codes in processUserInput() BufferedReader in = new BufferedReader (new InputStreamReader(System.in)); Prepare module to accept keyboard entry. strLine =in.readLine(); move entered value from keyboard to variable.
Do You want to add another number (y/n): y Enter a number 33 Accumulated Value: 77 Do You want to add another number (y/n): 5. main(String args[]){ use NestedExceptionTest.java main(String args[]){} as your template. }
“feel” Provides users with basic level of familiarity Built from GUI components (controls, widgets, etc.) User interacts with GUI component via mouse, keyboard, etc.
and javax.swing.JPanel. Places components sequentially (left to right) in the order they were added. It is also possible to specify the order of the components by using the Container method add, which takes a Component and an integer index position as arguments. BorderLayout Default for the content panes of JFrames (and other windows) and JApplets. Arranges the components into five areas: NORTH, SOUTH, EAST, WEST and CENTER. GridLayout Arranges the components into rows and columns.
public class PanelDemo { public JFrame f; public JPanel p; public JLabel lblNum1,lblNum2,lblNum3; public PanelDemo() { f = new JFrame("Grid Layout Demo"); p = new JPanel(); lblNum1 = new JLabel("First Name"); lblNum2 = new JLabel("Middle Name"); lblNum3 = new JLabel("Last Name"); }
public class PanelDemo2 { public JFrame f; public JPanel p,p2,p3,p4,p5,p6,p7; public JButton b1, b2, b3, b4, b5; public PanelDemo2() { f = new JFrame("Flow Layout Demo"); p = new JPanel(); b1 = new JButton("INSERT"); b2 = new JButton("UPDATE"); b3 = new JButton("DELETE"); b4 = new JButton("SELECT"); b5 = new JButton("CLOSE"); }
public class PanelDemo3 { public JFrame f; public JPanel p,p2,p3,p4,p5,p6,p7; public JButton b1, b2, b3, b4, b5; public PanelDemo3() { f = new JFrame("Border Layout Demo"); p = new JPanel(); b1 = new JButton("INSERT"); b2 = new JButton("UPDATE"); b3 = new JButton("DELETE"); b4 = new JButton("SELECT"); b5 = new JButton("CLOSE"); }
public class CombiLayoutDemo { public JFrame f; public JPanel p,p2,p3; public JLabel lblNum1,lblNum2,lblNum3; public JTextField txtNum1,txtNum2,txtNum3; public JButton b1, b2, b3, b4, b5; public CombiLayoutDemo() { //Frame f = new JFrame("Grid Layout Demo"); //Panels p = new JPanel(); p2 = new JPanel(); p3 = new JPanel();
Name"); lblNum3 = new JLabel("Last Name"); //textbox txtNum1 = new JTextField(25); txtNum2 = new JTextField(25); txtNum3 = new JTextField(25); //buttons b1 = new JButton("INSERT"); b2 = new JButton("UPDATE"); b3 = new JButton("DELETE"); b4 = new JButton("SELECT"); b5 = new JButton("CLOSE"); }
with which user interacts Event object Encapsulates information about event that occurred Event listener Receives event object when notified, then responds Programmer must perform two tasks Register event listener for event source Implement event-handling method (event handler)
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![f.setSize(500,500); f.setDefaultCloseOperation(f.EXIT_ON_CLOSE); f.pack(); f.setVisible(true); } public static void main(String[] args)](https://files.speakerdeck.com/presentations/4f22c85fa0a84d066a008812/slide_43.jpg){kind=link}
