shashank dwivedi

I want to achieve something like this in functional way. Any help ?

public static Function<String[],Void> validateLength3 = (String[] input) -> { if(input.length != 3) throw new  Exception("length not equals 3");}

I am sorry. FileWalkTree already gives what I wanted. Just was a little bit concerned about memory usages as it also uses DirectoryStream.

I wanted to list files at given depth only.

I want to collect directory structure to a given depth (It can be huge recursive structure!).
Which approach should perform better and consumes less memory?

Approach 1: Using DirectoryStream

   public void collectFilesTillDepth(Path path, int depth) {        if(depth == 0){            IPath p = IPath.TYPE.LEVEL.equals(rootPath.getType()) ? new LevelPath(path, rootPath.getRT()) : new BitFilePath(path, rootPath.getRT());            p.accept(flushVisitor);            return;        }        try (DirectoryStream<Path> ds =                     Files.newDirectoryStream(path)) {            for (Path p : ds) {                collectFilesTillDepth(p, --depth);                depth++;            }        } catch (IOException e) {            e.printStackTrace();        }    }


OR

Approach 2:

// Not tested and just for getting opinions    public void collectFilesTillDepthIO(File file, int depth) {        if(depth == 0){            System.out.println(file.getPath());        }        File[] children = file.listFiles();        if(null != children && children.length > 0)        for (File child : children) {            collectFilesTillDepthIO(child, --depth);            depth++;        }    }

Q. As java doc says -

    * <p> Note that the {@link java.nio.file.Files} class defines the {@link
    * java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method
    * to open a directory and iterate over the names of the files in the
    * directory. This may use less resources when working with very large
    * directories.

I am visiting directories in DFS manner(recursive approach), will java.io.File#listFiles perform better than DirectoryStream as stream entries won't be garbage collected till whole structure is visited (not sure on this) causing more memory usages?

annotations

I have to validate parameters in a method using custom annotation.
I am trying to get parameters (dataRequest  and token) in annotation handler.
Can someone help, I am not able to make this work. Here is what I have done so far.

Example:
   @ValidateData(message = "Invalid data found")    public Response storeData(DataRequest dataRequest, String token) throws Exception {    // proceed only if validated through annotations.. }



annotation declaration

@Documented @Constraint(validatedBy = {QueryValidator.class}) @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER}) public @interface ValidateData {    String message() default "Invalid data found in query";    Class<?>[] groups() default {};    Class<?>[] payload() default {}; }


public class QueryValidator implements ConstraintValidator<ValidateTags, Object[]> {      @Override    public void initialize(ValidateTags validateTags) {    }    @Override    public boolean isValid(Object[] objects, ConstraintValidatorContext constraintValidatorContext) {        for(Object o : objects){            // print all mehod parameters            System.out.println(o);        }        return false;    } }

I missed setting state properly.

int newstate = this.id == 3 ? 1:(id+1); state.setState(newstate);

Hi friends,

I am trying to execute three threads in sequence. Any help what I am missing?

I am expecting output to be:

thread1: 1
thread2: 1
thread3: 1
thread1: 2
thread2: 2
thread3: 2
thread1: 3
thread2: 3
thread3: 3


public class ThreadInSequence {    public static void main(String[] args) {        State sharedState = new State(1);                Thread t1 = new Thread(new Worker(sharedState,1),"thread1");        Thread t2 = new Thread(new Worker(sharedState, 2), "thread2");        Thread t3 = new Thread(new Worker(sharedState,3), "thread3");              t1.start();        t2.start();        t3.start();    } } class State {    private int state;    State(int state){        this.state = state;    }    public void setState(int state){        this.state = state;    }    public int getState(){        return this.state;    } } class Worker implements Runnable{    private int[] counts = {1,2,3};    private static State state;    private int id;    Worker(State state, int id){        this.state = state;        this.id = id;    }    public void run(){        synchronized (state) {            for (int i : counts) {                while(state.getState() != this.id){                    try {                        state.wait();                    } catch (InterruptedException e) {                        e.printStackTrace();                    }                }                System.out.println(Thread.currentThread().getName()+": " + i);                state.setState(2);                state.notifyAll();            }        }    } }

Hi folks,
I am stuck while trying to implement classical pattern mainly to learn best practices in js. I am not able to understand why my call to inherit method fails? Any help is much appreciated. Sorry for any layman's mistake.
Below is program.


;(function(global){  var Provider = function(){    log('creating Provider instance...');    return new Provider.init();  }  Provider.init = function(){        log('init invoked...');  }  // setting prototype of init and same as prototype of provider  Provider.init.prototype = Provider.prototype;  // private variables and functions  log = function log(msg){    if(console && msg){      console.log(msg);    }  }  // setting prototype to empty object to allow creating public methods  Provider.prototype = {    inherit : function(_clazz, _proto){        if(typeof _clazz !== 'undefined'){          throw 'Unable to create instance. Classname is required.';        }        var self = this;        _clazz.prototype =  function inherit(_proto){          self.log(_clazz+' -- prototype--> '+_proto || {});          function F(){};          F.prototype = _proto || {};          return new F();        }();    }  };  // setting alias to call using C$ from global  global.Provider = global.C$ = Provider; }(this)); /**************************************** TESTING ****************************************************************/ function main(){  function Animal(name){  }  Animal.prototype = {    logName : function(){      console.log('my name is '+ name);    }  }  function Fox(name){  }  console.log('Testing prototype');  C$().inherit(Fox.prototype,Animal.prototype);   // This call fails!!!  var animal = new Animal();  console.log(animal.prototype);  var fox = new Fox();  console.log(fox.prototype); } main();

What does it mean by @Retention(value=RUNTIME) in annotations?
Does it mean this annotation can be ignored at compile time even if the annotation class doesn't exist?
What if at runtime JVM fails to inject annotation using reflection (considering annotation doesn't exist)?

Found this link:
http://stackoverflow.com/questions/3567413/why-doesnt-a-missing-annotation-cause-a-classnotfoundexception-at-runtime

Please help me understand this concept.

Hi All,

I am trying a add a registration form(written in javafx) to my swing application.
I wanted to display this form as a popup , once register button is clicked.
I have written demo class below so far.The problem is JOptionPane is not able to display whole form.I am new to both swing and javafx.
Any help much appreciated.

Thanks.

package com.securegrc.scanner.panel; import java.awt.Dimension; import java.awt.FlowLayout; import javafx.application.Platform; import javafx.embed.swing.JFXPanel; import javafx.event.ActionEvent; import javafx.event.EventHandler; import javafx.geometry.Insets; import javafx.geometry.Pos; import javafx.geometry.Side; import javafx.scene.Group; import javafx.scene.Scene; import javafx.scene.control.Button; import javafx.scene.control.ContextMenu; import javafx.scene.control.Label; import javafx.scene.control.MenuItem; import javafx.scene.control.PasswordField; import javafx.scene.control.TextField; import javafx.scene.control.Tooltip; import javafx.scene.layout.GridPane; import javafx.scene.layout.HBox; import javafx.scene.text.Font; import javafx.scene.text.FontWeight; import javafx.scene.text.Text; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; import com.securegrc.cloud.client.scanner.nexpose.agent.logger.LogUtil; import com.securegrc.cloud.res.ResourceLoader; public class CustomerRegistrationPanel{ private final static int WIDTH = 800; private final static int HEIGHT = 500; private final String SCENE_TITLE ="Registration page"; private TextField loginEmailId; private TextField firstName; private TextField lastName; private PasswordField passwordField; private PasswordField retypePasswordField; private Button createAccountBtn; private ContextMenu validationContextMenu; private final String DEFAULT_VALIDATION_ERR_MSG = "This Field is mandatory."; private final String EMAIL_ID_VALIDATION_ERR_MSG = "Please enter a valid email Id."; private final String PASSWORD_NOT_MATCHED_ERR_MSG = "Passwords did not match."; private final String PASSWORD_POLICY_ERR_MSG = "Invalid Password."; private final String PASSWORD_HELP_TEXT = "Password length must be between 8 to 32 alphanumeric characters with atleast one digit."; public static final String PASSWORD_VALIDATION_REGEX = "\\A(?=\\S*?[A-za-z])(?=\\S*?[0-9])\\S{8,32}\\z"; public static final String EMAIL_VALIDATION_REGEX = "^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$"; public CustomerRegistrationPanel(){ } public JPanel createRegistrationPanal() { final JPanel panel = new JPanel(); panel.setLayout(new FlowLayout()); panel.setPreferredSize(new Dimension(500, 300)); panel.add(createJFXPanel()); System.out.println("created JPanel with containing JFXPanel"); return panel; } private JFXPanel createJFXPanel(){ final JFXPanel fxPanel = new JFXPanel(); Platform.setImplicitExit(true); Platform.runLater(new Runnable() { @Override public void run() { Scene scene = createScene(); fxPanel.setScene(scene); } }); return fxPanel; } private Scene createScene(){ Group root = new Group(); Scene scene = new Scene(root,WIDTH,HEIGHT); scene.getStylesheets().add (ResourceLoader.class.getResource("context.css").toExternalForm()); root.getChildren().add(loadLoginScreen()); return (scene); } private GridPane loadLoginScreen() { GridPane grid = new GridPane(); grid.setAlignment(Pos.CENTER); grid.setHgap(10); grid.setVgap(10); grid.setPadding(new Insets(25, 25, 25, 25)); Text scenetitle = new Text(SCENE_TITLE); scenetitle.setFont(Font.font("Tahoma", FontWeight.NORMAL, 20)); grid.add(scenetitle, 0, 0, 2, 1); firstName = createTextField(); lastName = createTextField(); loginEmailId = createTextField(); addLabelComponentToGrid(grid, "First Name: ", firstName, 0, 1); addLabelComponentToGrid(grid, "Last Name: ", lastName, 0, 2); addLabelComponentToGrid(grid, "Login Email Id: ", loginEmailId, 0, 3); Label password = new Label("Password:"); grid.add(password, 0, 4); passwordField = new PasswordField(); Tooltip tooltip = new Tooltip(PASSWORD_HELP_TEXT); passwordField.setTooltip(tooltip); grid.add(passwordField, 1, 4); Label retypepassword = new Label("Retype Password:"); grid.add(retypepassword, 0, 5); retypePasswordField = new PasswordField(); grid.add(retypePasswordField, 1, 5); createAccountBtn = new Button("Create Account"); HBox btnPanel = new HBox(10); btnPanel.setAlignment(Pos.BOTTOM_RIGHT); btnPanel.getChildren().add(createAccountBtn); grid.add(btnPanel, 1, 6); // Context Menu for error messages validationContextMenu = new ContextMenu(); validationContextMenu.setAutoHide(false); // Action on button press addActionListeners(); return grid; } private void addLabelComponentToGrid(GridPane grid ,String labelName,TextField labelTxtField,int x , int y){ Label label = new Label(labelName); grid.add(label, x, y); grid.add(labelTxtField, x+1, y); } TextField createTextField(){ TextField txtField = new TextField(); txtField.setMinWidth(200); return txtField; } private void addActionListeners() { createAccountBtn.setOnAction(new EventHandler<ActionEvent>() { @Override public void handle(ActionEvent e) { validateFields(); } }); } private void clearValidationText(){ validationContextMenu.getItems().clear(); } private void validateFields(){ clearValidationText(); if (firstName.getText().equals("")) { showErrValidationMessgage(firstName, DEFAULT_VALIDATION_ERR_MSG); firstName.setFocusTraversable(true); } else if(lastName.getText().equals("")){ showErrValidationMessgage(lastName, DEFAULT_VALIDATION_ERR_MSG); } else if(!isValidLogin()){ showErrValidationMessgage(loginEmailId, EMAIL_ID_VALIDATION_ERR_MSG); loginEmailId.clear(); } else if(!isValidPassword()){ showErrValidationMessgage(passwordField, PASSWORD_POLICY_ERR_MSG); passwordField.clear(); retypePasswordField.clear(); } else if(!passwordMatched()){ showErrValidationMessgage(retypePasswordField, PASSWORD_NOT_MATCHED_ERR_MSG); passwordField.clear(); retypePasswordField.clear(); } } private boolean passwordMatched(){ String password = passwordField.getText(); String retypePassword = retypePasswordField.getText(); if(!password.equals(retypePassword)) return false; return true; } private boolean isValidPassword(){ String passwd = passwordField.getText(); if(!passwd.matches(PASSWORD_VALIDATION_REGEX)){ return false; } return true; } private boolean isValidLogin(){ if(loginEmailId.getText().trim().matches(EMAIL_VALIDATION_REGEX)) return true; return false; } private void showErrValidationMessgage(TextField textField , String message){ MenuItem validationMenuItem = new MenuItem(message); validationMenuItem.setId("validation-menu"); validationContextMenu.setId("validation-context"); validationContextMenu.getItems().add(validationMenuItem); validationContextMenu.show(textField, Side.RIGHT, 10, 0); } /********************************************************************************************************** * Testing * ********************************************************************************************************/ public static void main(String[] args) { final CustomerRegistrationPanel regPanel = new CustomerRegistrationPanel(); final JPanel jpanel = regPanel.createRegistrationPanal(); final JFrame parent = new JFrame(); JButton button = new JButton(); button.setText("Click me to show dialog!"); parent.add(button); parent.pack(); parent.setVisible(true); button.addActionListener(new java.awt.event.ActionListener() { @Override public void actionPerformed(java.awt.event.ActionEvent evt) { JOptionPane dialog = new JOptionPane(); JOptionPane.showOptionDialog(null,jpanel , "", JOptionPane.DEFAULT_OPTION, JOptionPane.DEFAULT_OPTION, null, new Object[] {}, null); } }); } }

I am new to JPA and need some help understanding persisting JPA parent entity along with it's child (through Mapping).
Say I have following two entities

//all imports @Entity @Cacheable(false) @Table(name="employee") class Employee{ @Id @SequenceGenerator(name="SEQ", allocationSize=25) @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="SEQ") @Column(name="e_id") //in mysql db it is auto_increment private long eId; @Column(name="email_id") private String emailId; @Column(name="f_name") private String fName; //more column names @OneToMany(mappedBy="emp", fetch=FetchType.EAGER, cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH, CascadeType.REMOVE}) private ArrayList<Address> addresses; // all getters and setters } @Entity @Cacheable(false) @Table(name="address") class Address{ @Id @SequenceGenerator(name="add_SEQ", allocationSize=25) @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="add_SEQ") @Column(name="address_id") private int address_id; @Column(name="e_id" ,insertable = false , updatable = false) private long e_id; // have a foreign key relation in database with employee @Column(name="email_id") private String emailId; @ManyToOne(fetch = FetchType.EAGER) @JoinColumns( { @JoinColumn(name = "email_id", referencedColumnName = "email_id", insertable = false, updatable = false), @JoinColumn(name = "e_id", referencedColumnName = "e_id", insertable = true, updatable = false) }) private Employee emp; // all getters and setters }

Now I am trying to save Employee setting Address Entity to it.But it throws a foreign key validation exception because e_id is auto_increment and is generated by database while save.
Does JPA provide some mechanism to handle this ?

Thanks Rico and Henry for clearing my doubts..

http://www.jacobward.co.uk/automating-client-side-password-encryption-for-phpcurl-web-bot-form-submission/

got one solution here using JS...

yes correct but then while childThread is executing(say it is going to complete after 5 min) , can't its parent thread release the lock?

class A { public synchronized method() { //start a new thread childThread here------>Line 1 } }

here lets say a thread is accessing synchronized method() and a new childThread is started at line 1.
can some other thread access synchronized method while childThread is still running??