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Having to automatically highlight specific String from a text field to a text area

I am now wondering how to automatically highlight the text within a text area. I have researched further and found a method to do so however I am not sure how it can still highlight a String automatically after the user enters search.
Note: Ignore the radio buttons
Here is the method I tried within the action event when clicking the search button
#FXML
private void searchButton(ActionEvent actionEvent){
String key = keyField.getText();
String field = textField.getText();
System.out.println(key);
System.out.println(field);
textField.getText();
if (textField.getText().equals(key)) {
textField.setStyle("-fx-highlight-fill: yellow; -fx-highlight-text-fill: black; -fx-font-size: 12px; ");
textField.setEditable(false);
textField.addEventFilter(MouseEvent.ANY, new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent t) {
t.consume();
}
});
Platform.runLater(new Runnable() {
#Override
public void run() {
textField.selectRange(13, 18);
}
});
}
ToggleGroup group = new ToggleGroup();
rabinKarpp.setToggleGroup(group);
kmp.setToggleGroup(group);
naive.setToggleGroup(group);
ArrayList indexes = new ArrayList();
if (rabinKarpp.isSelected()){
indexes = RabinKarp.process(field, key);
}
else if (kmp.isSelected()){
indexes = KMPAlgo.process(field, key);
}
else if (naive.isSelected()){
indexes = NaiveAlgo.process(field, key);
}
else if(!naive.isSelected() && !kmp.isSelected() && !rabinKarpp.isSelected()) {
Alert alert = new Alert(Alert.AlertType.WARNING, "Select an algorithm first before proceeding.",ButtonType.OK);
alert.showAndWait();
}
}
the expected output should be the "hello" from "hello everyone" to be highlighted but I'm still stumped on how to do so.
EDIT:
The code now looks like this but still the highlights will not turn up sadly.
#FXML
protected void searchButton(ActionEvent actionEvent){
String key = keyField.getText();
String field = textField.getText();
System.out.println(key);
System.out.println(field);
ToggleGroup group = new ToggleGroup();
rabinKarpp.setToggleGroup(group);
kmp.setToggleGroup(group);
naive.setToggleGroup(group);
ArrayList indexes = new ArrayList();
if (rabinKarpp.isSelected()){
indexes = RabinKarp.process(field, key);
}
else if (kmp.isSelected()){
indexes = KMPAlgo.process(field, key);
}
else if (naive.isSelected()){
indexes = NaiveAlgo.process(field, key);
}
else if(!naive.isSelected() && !kmp.isSelected() && !rabinKarpp.isSelected()) {
Alert alert = new Alert(Alert.AlertType.WARNING, "Select an algorithm first before proceeding.",ButtonType.OK);
alert.showAndWait();
}
}
#Override
public void initialize(URL url, ResourceBundle resourceBundle) {
List<List<Integer>> locations = new ArrayList();
keyField.textProperty().addListener((o, oldValue, newValue) -> {
Pattern pattern = Pattern.compile(newValue);
Matcher matcher = pattern.matcher(textField.getText());
locations.clear();
if (newValue.isEmpty()) {
// no highlighting for the empty search string
textField.deselect();
} else {
int index = textField.getText().indexOf(newValue);
if (index < 0) {
// text not found
textField.deselect();
} else {
while(matcher.find())
{
List<Integer> tempList = new ArrayList<>();
tempList.add(matcher.start());
tempList.add(matcher.end());
locations.add(tempList);
}
}
}
});
AtomicInteger currentIndex = new AtomicInteger(-1);
downButton.setOnAction((t) -> {
if(currentIndex.get() >= -1 && currentIndex.get() < locations.size() - 1)
{
textField.selectRange(locations.get(currentIndex.incrementAndGet()).get(0), locations.get(currentIndex.get()).get(1));
}
});
upButton.setOnAction((t) -> {
if(currentIndex.get() > 0 && currentIndex.get() <= locations.size())
{
textField.selectRange(locations.get(currentIndex.decrementAndGet()).get(0), locations.get(currentIndex.get()).get(1));
}
});
}

Simply listen to the text property of the TextField for this purpose. Note that you can only select a single range using TextArea. If you need to highlight multiple occurances you may want to use a TextFlow and it's rangeShape method as suggested by #Slaw.
#Override
public void start(Stage stage) throws IOException {
TextArea textArea = new TextArea();
VBox.setVgrow(textArea, Priority.ALWAYS);
Random random = new Random();
for (int l = 0; l < 10; l++) {
for (int i = 0; i < 300; i++) {
textArea.appendText(Character.toString('a' + random.nextInt('z'- 'a' + 1)));
}
textArea.appendText("\n");
}
TextField textField = new TextField();
textField.textProperty().addListener((o, oldValue, newValue) -> {
if (newValue.isEmpty()) {
// no highlighting for the empty search string
textArea.deselect();
} else {
int index = textArea.getText().indexOf(newValue);
if (index < 0) {
// text not found
textArea.deselect();
} else {
// select first occurance
textArea.selectRange(index, index + newValue.length());
}
}
});
Scene scene = new Scene(new VBox(textArea, textField));
stage.setScene(scene);
stage.show();
}
Using fxml the proper place to register a listener like this would be the initialize method.

I would like to add on to #fabian's answer. If you want to find multiple occurrences one at a time, you can find all the matches in the string and save their indexes to a list. The list can be used to step through each occurrence.
I have added 4 occurrences of hello to fabian's original string. You can type hello into the TextField and hit up and then down, to reach each occurrence.
TextArea textArea = new TextArea();
VBox.setVgrow(textArea, Priority.ALWAYS);
Random random = new Random();
for (int l = 0; l < 10; l++) {
for (int i = 0; i < 300; i++) {
textArea.appendText(Character.toString('a' + random.nextInt('z'- 'a' + 1)));
}
textArea.appendText("\n");
}
textArea.replaceText(0, 5, "hello");
textArea.replaceText(20, 25, "hello");
textArea.replaceText(30, 35, "hello");
textArea.replaceText(textArea.getText().length() - 6, textArea.getText().length() -1, "hello");
TextField textField = new TextField();
List<List<Integer>> locations = new ArrayList();
textField.textProperty().addListener((o, oldValue, newValue) -> {
Pattern pattern = Pattern.compile(newValue);
Matcher matcher = pattern.matcher(textArea.getText());
locations.clear();
if (newValue.isEmpty()) {
// no highlighting for the empty search string
textArea.deselect();
} else {
int index = textArea.getText().indexOf(newValue);
if (index < 0) {
// text not found
textArea.deselect();
} else {
while(matcher.find())
{
List<Integer> tempList = new ArrayList<>();
tempList.add(matcher.start());
tempList.add(matcher.end());
locations.add(tempList);
}
}
}
});
AtomicInteger currentIndex = new AtomicInteger(-1);
Button btnDown = new Button("Down");
btnDown.setOnAction((t) -> {
if(currentIndex.get() >= -1 && currentIndex.get() < locations.size() - 1)
{
textArea.selectRange(locations.get(currentIndex.incrementAndGet()).get(0), locations.get(currentIndex.get()).get(1));
}
});
Button btnUp = new Button("Up");
btnUp.setOnAction((t) -> {
if(currentIndex.get() > 0 && currentIndex.get() <= locations.size())
{
textArea.selectRange(locations.get(currentIndex.decrementAndGet()).get(0), locations.get(currentIndex.get()).get(1));
}
});
Scene scene = new Scene(new VBox(textArea, textField, new HBox(btnDown, btnUp)));
stage.setScene(scene);
stage.show();

Array of Label. Primes Generator. JavaFX

I am trying to develop a program to generate 10 prime numbers each time a button is pressed but I am struggling. The code to identify the primes is correct but I get the error NullPointerException probably because I am handling the Label Array badly. I'll paste the code below, thanks for any tip on what's going wrong.
public class PrimeGenerator extends Application {
Button generate;
Label listNumbers;
int i;
int multiple = 2;
int number = 2;
int z = 1;
int t = 0;
Label[] primeList;
#Override
public void start(Stage primaryStage) throws Exception {
VBox root = new VBox();
generate = new Button("Generate 10 more primes!");
generate.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent e) {
primeList = new Label[10];
while (i < primeList.length) {
multiple = 2;
while (multiple < number) {
t = number % multiple;
if ((t == 0)) {
z = 0;
}
multiple++;
}
// Here I'd like to add the prime number to the array while also adding the Label to the Vbox
if ((z == 1)) {
primeList[i].setText(Integer.toString(number));
root.getChildren().add(primeList[i]);
i++;
}
z = 1;
number++;
}
}
});
root.getChildren().add(generate);
Scene scene = new Scene(root);
primaryStage.setTitle("Prime Numbers Generator");
primaryStage.setScene(scene);
primaryStage.show();
}
}

I think you forgot to initialize the array element
....
primeList[i] = new Label();
primeList[i].setText(Integer.toString(number));
....
You can also in one line
primeList[i] = new Label(Integer.toString(number));
For example
if ((z == 1)) {
primeList[i] = new Label();
primeList[i].setText(Integer.toString(number));
root.getChildren().add(primeList[i]);
i++;
}
Alternatively, you can pre-create elements in advance:
...
#Override
public void handle(ActionEvent e) {
primeList = new Label[10];
for(int labelIdx=0; labelIdx<primeList.length; labelIdx++)
primeList[labelIdx] = new Label();
while (i < primeList.length) {
...

Javafx creating players and pieces for chutes and ladders

I have an assignment where I am to create a chutes and ladder game using JavaFX.
What I am currently stuck on is once the user selects how many players they want, the method I run pushes an error.
I have run it through the debugger and I know what line is the problem, but I have no idea where to go from here.
The exception is:
Exception in thread "JavaFX Application Thread"
java.lang.ArrayIndexOutOfBoundsException: 0
I found that if I change the zero in private Players [] players = new Players[0]; to a 4, it works. However, I get another error if I try to change the 0 in private Circle [] c = new Circle[0];
public class Main extends Application {
private final int BOARD_DIM = 10;
private Players [] players = new Players[0];
private Circle [] c = new Circle[0];
public static void main(String[]args){
launch();
}
public void start(Stage pStage) throws Exception{
//ROOT PANE
BorderPane root = new BorderPane();
//MENUBAR
//BOARD CREATION
//PLAYER SELECTION/RESUME PREVIOUS GAME
//Drop down menu
HBox players = new HBox();
Label intro = new Label("Select # of players");
ChoiceBox<String> p = new ChoiceBox<>();
p.getItems().addAll("2","3","4");
p.setPadding(new Insets(6));
//Button to start new game
Button startGame = new Button("Start Game");
startGame.setOnAction(e -> getChoice(p));
startGame.setPadding(new Insets(10));
players.getChildren().addAll(intro,p,startGame);
root.setRight(players);
Scene scene = new Scene(root, 900, 650);
pStage.setTitle("Chutes and Ladders");
pStage.setScene(scene);
pStage.show();
}
private void getChoice(ChoiceBox<String> p) {
int numOfPlayers = Integer.parseInt(p.getValue());
for(int i = 0; i < numOfPlayers; i++){
players[i] = new Players("p"+(i+1),9,0, false);
c[i] = new Circle(25);
}
c[0].setFill(Color.GREEN);
c[1].setFill(Color.YELLOW);
if(numOfPlayers >= 3){
c[2].setFill(Color.RED);
}
if(numOfPlayers == 4){
c[3].setFill(Color.BLACK);
}
}

You are initalizing players and c as arrays with length 0. And in the loop you are iterating over the elements from 0 to numOfPlayers. That's what is causing the exception.
First just declare your arrays:
private Players [] players;
private Circle [] c;
Then in the your method, initalize the arrays with the length you need (If you need to alter the length later I would suggest to switch to ArrayLists).
private void getChoice(ChoiceBox<String> p) {
int numOfPlayers = Integer.parseInt(p.getValue());
c = new Circle[numOfPlayers]; //add these lines
players = new Players[numOfPlayers]; //add these lines
for(int i = 0; i < numOfPlayers; i++){
players[i] = new Players("p"+(i+1),9,0, false);
c[i] = new Circle(25);
}
...
}

link logic class into my gui class java

hello i was wondering how do i link my logic class to my gui class?
i have wrote a logic class which is the structure then had to give it an interface; so i wrote another class which is the gui class but idk how to make the GUI class grab the variable from the logic class.
P.S: its a number guessing game that the user has to guess a numb btw 1-10.
LOGIC CLASS
import java.util.InputMismatchException;
import java.util.Random;
import java.util.Scanner;
public class GG {
public static void main(String[] args)
{
//random number
Random rand = new Random();
int answer = rand.nextInt(10) +1;
int guess = 0;
int attempts = 0;
public
//user's guess
Scanner keyboard = new Scanner(System.in);
GuessingGameGui gui = new GuessingGameGui();
gui.setVisible(true);
while(answer != guess)
{
try
{
System.out.print("Guess a number between 1 and 10: ");
attempts++;
guess = keyboard.nextInt();
if (guess < 1 || guess > 10)
//throw new BadGuessException()
throw new BadGuessException("invalid entry (" + attempts + " attempts so far)");
}
catch (BadGuessException e)
{
System.out.println(e.getMessage());
}
catch (InputMismatchException e)
{
System.out.println("Please enter integers only, and try again");
keyboard.next(); //to get rid of infinite loop issue
}
}
System.out.println("YOU GOT IT (" + attempts + "attempts )");
}
}
GUI CLASS
public class GuessingGameGui extends JFrame {
public GuessingGameGui() {
final int WINDOW_WIDTH = 650; // Window width in pixels
final int WINDOW_HEIGHT = 250; // Window height in pixels
setTitle("Guessing Game");
setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel north = new JPanel();
JLabel lab1 = new JLabel("Guess a number between 1 and 10?");
setLayout(new FlowLayout());
north.add(lab1);
add( north );
JPanel center = new JPanel();
final JTextField titleText = new JTextField();
titleText.setPreferredSize( new Dimension( 200, 24 ) );
setLayout(new FlowLayout());
JButton button = new JButton("Guess");
Action action = new AbstractAction()
{
#Override
public void actionPerformed(ActionEvent e)
{
String typed = titleText.getText();
int guess = Integer.parseInt(typed);
}
};
titleText.addActionListener( action );
button.addActionListener( action );
center.add(titleText);
center.add(button);
add( center );
JPanel south = new JPanel();
JLabel lab2 = new JLabel("YOU GOT IT " + attempts);
south.add(lab2);
add( south );
}
}

A common way is to add the Logic object to the GUI, for example through the constructor. Then whenever something is happening on the GUI you need to call the correct methods on the Logic object and update the display if needed.

java Clear Table on button click

I am writing a Mortgage Calculator for class and I have it working the way I need it to, except everytime I click the "Calculate" button it will just continue to add to the table instead of the table clearing and showing new values. I know my code might look a little sloppy and I have some things commented out that don't need to be there because I'm still working it, but do you have any suggestions?
FYI I am still a beginner learning Java and it has taken me over 20hrs to get this far (and i"m pretty proud of myself!) Thank you!!
//Import all required Packages
import javax.swing.*;
import javax.swing.table.*;
import java.awt.*;
import java.text.*;
import java.awt.event.*;
public class MortgageCalculator extends JFrame implements ActionListener {
// Loan Values
double intPrincipal, interestRate, calcPayment, monthlyInterest, currentInterest, principalPaid, newBalance;
int totalMonths;
double[] loanInterest = {5.35, 5.5, 5.75}; // Yearly interest in decimal form
int[] loanTerm = {7, 15, 30}; // Total months of term
String principal;
String comboArray[] = {"7 Years at 5.35%", "15 Years at 5.5%", "30 Years at 5.75%"};
int termYears, termMonths, done, i=0, m=0, p=0;
//Set up panels
JPanel contentPanel;
//Set up labels
JLabel mortgageLabel, paymentLabel, termLabel;
//Set up buttons
JButton calculateButton, clearButton, exitButton;
//TextFields
JTextField txtMortgage = new JTextField(10);
JTextField txtPayment = new JTextField(10);
//New Text Area
JTextArea textarea = new JTextArea();
DecimalFormat df = new DecimalFormat("$###,###.00"); //Formatting the results to decimal form
//Combo Box
JComboBox loansList = new JComboBox();
DefaultTableModel model = new DefaultTableModel();
JTable table = new JTable(model);
//Build GUI
public MortgageCalculator()
{
super();
initializeContent();
}
public void initializeContent()
{
this.setSize(700, 500);
this.setLocation(0, 0);
this.setContentPane(contentPanel());
this.setTitle("Mortgage Calculator");
}
public JPanel contentPanel()
{
contentPanel = new JPanel();
contentPanel.setLayout(null);
//Add labels to the panel
mortgageLabel = new JLabel("Mortgage:");
mortgageLabel.setLocation(200, 30);
mortgageLabel.setSize(100, 25);
contentPanel.add(mortgageLabel);
termLabel = new JLabel("Term & Rate:");
termLabel.setLocation(183, 55);
termLabel.setSize(100, 30);
contentPanel.add(termLabel);
paymentLabel = new JLabel("Monthly Payment:");
paymentLabel.setLocation(158, 85);
paymentLabel.setSize(100, 30);
contentPanel.add(paymentLabel);
//Text Fields
txtMortgage = new JTextField(10);
txtMortgage.setLocation(280, 30);
txtMortgage.setSize(150, 25);
contentPanel.add(txtMortgage);
txtPayment = new JTextField(10);
txtPayment.setLocation(280, 85);
txtPayment.setSize(150, 25);
contentPanel.add(txtPayment);
//Combo Box
loansList.addItem(comboArray[0]);
loansList.addItem(comboArray[1]);
loansList.addItem(comboArray[2]);
loansList.setLocation(280, 55);
loansList.setSize(150, 25);
loansList.addActionListener(this);
contentPanel.add(loansList);
//textarea.setPreferredSize(new Dimension(650, 300));
//JScrollPane scroller = new JScrollPane(textarea);
JScrollPane scroller = new JScrollPane(table);
contentPanel.add(scroller);
scroller.setSize(650,300);
scroller.setLocation(20, 150);
textarea.setLineWrap(true);
model.addColumn("Payment Number");
model.addColumn("Current Interest");
model.addColumn("Principal Paid");
model.addColumn("New Balance");
//Buttons
exitButton = new JButton("Exit");
exitButton.setLocation(450, 30);
exitButton.setSize(100, 25);
contentPanel.add(exitButton);
clearButton = new JButton("Clear");
clearButton.setLocation(450, 55);
clearButton.setSize(100, 25);
contentPanel.add(clearButton);
calculateButton = new JButton("Calculate");
calculateButton.setLocation(450, 85);
calculateButton.setSize(100, 25);
contentPanel.add(calculateButton);
//setup up buttons
calculateButton.addActionListener(this);
clearButton.addActionListener(this);
exitButton.addActionListener(this);
return contentPanel;
}
//Define actions performed for buttons
public void actionPerformed(ActionEvent e)
{
String arg = e.getActionCommand();
if (e.getSource() == loansList) {
switch (loansList.getSelectedIndex()) {
case 0:
i = 0;
break;
case 1:
i = 1;
break;
case 2:
i = 2;
break;
}
}
if (arg == "Calculate")
{
txtPayment.setText("");
principal = txtMortgage.getText();
try {
intPrincipal = Double.parseDouble(principal);
if (intPrincipal <= 0) throw new NumberFormatException();
}
catch(NumberFormatException n){
txtPayment.setText("Please Enter a Postive Numeric Number");
done = 1;
}
if (done == 1)
done = 0;
else {
interestRate = loanInterest[i];
termYears = loanTerm[i];
monthlyInterest = interestRate/(12*100); //calculates monthly interest
termMonths = termYears*12; //calculates term length in months
calcPayment = monthlyInterest*intPrincipal/(1-Math.pow((1+monthlyInterest), -termMonths)); //calculates monthly payment
txtPayment.setText(" " + df.format(calcPayment));
for (m=0; m<=totalMonths; m++) {
totalMonths = loanTerm[i]*12;
currentInterest = intPrincipal * monthlyInterest;
principalPaid = calcPayment - currentInterest;
newBalance = intPrincipal - principalPaid;
intPrincipal = newBalance;
/* printAndAppend(
(m+1) + " " +
df.format(currentInterest) + " " +
df.format(principalPaid) + " " +
df.format(newBalance) + "\n");
//textarea.setText(df.format(currentInterest));
if(intPrincipal <= 1){ break;}*/
// Create a couple of columns
model.addRow(new Object[]{m+1, df.format(currentInterest), df.format(principalPaid), df.format(newBalance)});
if(intPrincipal <= 1){ break;}
}
}
}
else if (e.getSource() == clearButton)
{
txtMortgage.setText(""); //clear Mortgage textfield
txtPayment.setText(""); //clear Payment textfield
txtMortgage.requestFocusInWindow(); //move cursor back to Mortgage textfield
loansList.setSelectedIndex(0);
}
else if (e.getSource() == exitButton)
System.exit(0);
}
public void printAndAppend(String text) {
textarea.append(text);
}
public static void main(String[] args)
{
new MortgageCalculator().setVisible(true);
}
}

To clear all you need to do is set the row count of the model to 0 -- that's it:
else if (e.getSource() == clearButton) {
txtMortgage.setText("");
txtPayment.setText("");
txtMortgage.requestFocusInWindow();
loansList.setSelectedIndex(0);
model.setRowCount(0); //!! added
}
Also, this is not good:
if (arg == "Calculate") {
As you shouldn't use == to compare Strings. If you want to compare Strings, use the equals method:
if (arg.equals("Calculate")) {
or the equalsIgnoreCase method:
if (arg.equalsIgnoreCase("Calculate")) {
The reason this is important is because == checks to see if one String object is the same as another String object, and you really don't care about this. Instead you want to know if one String holds the same chars as another, and that's what equals tests for.
Also, I'd set the model's row count to 0 at the beginning of your calculate method, and this way you can recalculate things without having to clear.