Swing Application Window - Yash-777/LearnJava GitHub Wiki

JOptionPane (constructor)

Creates a JOptionPane with the specified buttons, icons, message, title, and so on. You must then add the option pane to a JDialog, register a property-change listener on the option pane, and show the dialog. See Stopping Automatic Dialog Closing for details.

public class UserConformation {
    public static void main(String[] argv) throws Exception {
        int i = okcancel("User Conformation", "Are you sure you want to quit?");
        System.out.println("User Action : OK/YES[0], NO[1], Cancel[2], [X][-1] Value: "+i);
        
        printerSelection();
    }

    public static int okcancel(String title, String msg) {
        int result = JOptionPane.showConfirmDialog(null, msg, title,
                JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE);
        return result;
    }
    
    public static void printerSelection() {
        String bigList[] = new String[10];
        for (int i = 0; i < bigList.length; i++) {
            bigList[i] = Integer.toString(i);
        }

        Object showInputDialog = JOptionPane.showInputDialog(null, "Pick a printer", "Input",
                JOptionPane.QUESTION_MESSAGE, null, bigList, "Titan");
        System.out.println("User Choosen Vlaue : "+ showInputDialog);
    }
}

Swing Components:

Examples with JNLP sources:

The table that follows lists every example in the Using Swing Components lesson, with links to required files and to where each example is discussed. The first column of the table has links to JNLP files that let you run the examples using Java Web Start.

Example to Shutdown system in X Seconds: Stackpost

public class UserConformation extends JFrame {

    static Container contentPane;
    public UserConformation() {
        contentPane = getContentPane();
        contentPane.setBackground(Color.DARK_GRAY);
        setTitle("Confirm Dialog in Frame");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
        setResizable(false);
        setSize(400, 300);
        contentPane.setLayout(null);
    }
    
    static boolean isToShutDown = true;
    public static void main(String[] argv) throws Exception {
        
        shutDownSys(10);
        
        int i = okcancel("User Conformation", "Are you sure to shutdown the System?");
        System.out.println("User Action : OK/YES[0], NO[1], Cancel[2], [X][-1] Value: "+i);
        if (i == 2) {
            isToShutDown = false;
        }
    }

    public static int okcancel(String title, String msg) {
        int result = JOptionPane.showConfirmDialog(new UserConformation(), msg, title,
                JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE);
        return result;
    }
    
    public static void shutDownSys(int sec) {
        Timer timer = new Timer();
        timer.schedule(new TimerTask() {
            @Override
            public void run() {
                if (isToShutDown) {
                    /*ProcessBuilder processBuilder = new ProcessBuilder("shutdown","/s");
                    processBuilder.start();*/
                    System.err.println("Time out: Shutdown the system");
                } else {
                    System.out.println("Time out: User canceld for System Shutdown");
                }
                System.exit(0);
            }
        }, sec * 1000);
        System.out.println(" Shutting down in " + sec + " seconds");
    }
}

Post: JTextField in JDialog retaining value after dispose

In a class-based object-oriented language, in general, state is carried by instances, methods are carried by classes, and inheritance is only of structure and behavior.

Method signature: It consists of method name and parameter list (number/type/order of the parameters). methodName(parametersList y). An instance method in a subclass with the same signature and return type as an instance method in the super-class overrides the super-class's method.

Java OOP concepts
Class  - Collection of a common features of a group of object [static/instance Fields, blocks and Methods]
Object - Instance of a class (instance fields)
Abstraction - Process of hiding complex info and providing required info like API, Marker Interfaces ...
Encapsulation(Security) - Class Binding up with data members(fields) and member functions.
Inheritance  (Reusability by placing common code in single class)
 1. Multilevel - {A -> B -> C} 2. Multiple - Diamond problem {A <- (B) -> C} [Java not supports] 3. Cyclic {A <-> B} [Java not supports]
 * Is-A   Relation - Class A extends B
 * Hash-A Relation - Class A { B obj = new B(); } - (Composition/Aggregation)
Polymorphism (Flexibility) 1. Compile-Time Overloading    2. Runtime Overriding  [Greek - "many forms"]


int[] arr = {1,2,3}; int arrLength = arr.length;   // Fixed length of sequential blocks to hold same data type
String str = "Yash"; int strLength = str.length(); // Immutable Object value can't be changed.

List<?> collections = new ArrayList<String>(); int collectionGroupSize = collections.size();
Map<?, ?> mapEntry = new HashMap<String, String>();
Set<?> keySet = mapEntry.keySet(); // Set of Key's
Set<?> entrySet = mapEntry.entrySet(); // Set of Entries [Key, Value]

// Immutable Objects once created they can't be modified. final class Integer/String/Employee
Integer val = Integer.valueOf("100"); String str2 = String.valueOf(100); // Immutable classes
final class Employee { // All Wrapper classes, java.util.UUID, java.io.File ...
    private final String empName; // Field as Final(values can be assigned only once) Only getter functions.
    public Employee(String name) { this.empName = name; }
}

Native Java Code for Hashtable.h, Hashtable.cpp SQL API.

You can check your current JDK and JRE versions on your command prompt respectively,

  • JDK javac -version [C:\Program Files\Java\jdk1.8.0_121\bin] o/p: javac 1.8.0_121
  • JRE java -version [C:\Program Files\Java\jdk1.8.0_121\bin] o/P: java version "1.8.0_102"

JAVA_HOME - Must be set to JDK otherwise maven projects leads to compilation error. [ERROR] No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK? C:\Softwares\OpenJDK\, 7-zip

Fatal error compiling: invalid target release: JRE and JDK must be of same version 1.8.0.XXX

Disable TLS 1.0 and 1.1security-libs/javax.net.ssl: TLS 1.0 and 1.1 are versions of the TLS protocol that are no longer considered secure and have been superseded by more secure and modern versions (TLS 1.2 and 1.3).

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