Mona Smith

Thanks to everyone who replied. I ended up using the GridBag layout which worked better in my case, since my two buttons were different sizes. Now I'm just having some troubles linking together the JFrames to the main Frame once 'Start' is pressed, but I should be able to figure that out soon!

Thanks Rob Camick, it was a dumb mistake on my part!

Hello, I am trying to make a snake program but I'm having some trouble with the main screen. I am trying to make the Snake title, a start button, and a back button, but the Start button seems to be taking up the whole page and I can't figure out why. I am also trying to use Box Layout to create vertical boxes but that's not working either. My code is attached below:

package snake; import java.awt.Color; import java.awt.FlowLayout; import java.awt.Font; import java.awt.Graphics; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.BorderFactory; import javax.swing.BoxLayout; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; public class Start { public static void main(String[] args) { startScreen startFrame=new startScreen(); } } // change name of this class startScreen extends JFrame { // constructor public startScreen() { // fonts Font snakeTitleFont=new Font("Arial", Font.BOLD, 50); Font buttonFont=new Font("Arial", Font.CENTER_BASELINE, 20); // text JLabel snakeTitle=new JLabel("Snake"); snakeTitle.setVerticalTextPosition(JLabel.CENTER); snakeTitle.setFont(snakeTitleFont); add(snakeTitle); // start button JButton startButton=new JButton("Start"); startButton.setLayout(null); startButton.setBackground(Color.MAGENTA); startButton.setOpaque(true); startButton.setBorderPainted(false); startButton.setFont(buttonFont); this.setLayout(new BoxLayout(this, BoxLayout.LINE_AXIS)); add(startButton); // action listener for start btn startButton.addActionListener(new ActionListener() { // once this is clicked on, it should call the GUI @Override public void actionPerformed(ActionEvent e) { new Frame(); // closes the old form after start is clicked dispose(); } }); // back button JButton backButton=new JButton("Start"); backButton.setLayout(null); backButton.setBackground(Color.YELLOW); backButton.setOpaque(true); backButton.setBorderPainted(false); backButton.setFont(buttonFont); backButton.setBounds(getBounds());                this.setLayout(new BoxLayout(this, BoxLayout.LINE_AXIS)); add(backButton); // action listener for start btn startButton.addActionListener(new ActionListener() { // once this is clicked on, it should call the GUI @Override public void actionPerformed(ActionEvent e) { new Frame(); // closes the old form after start is clicked dispose(); } }); this.setVisible(true); this.setSize(800, 500); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setResizable(false); this.setLocationRelativeTo(null); } }

Any help would be appreaciated as to why this is happening.

My goal is to create a simple snake game. I was expecting to get the snake to move around on the screen, but I am getting the error:

Syntax error, insert "SimpleName" to complete InterfaceType.

I'm not sure what this means but it has to do with private class Key implements @KeyListener at the bottom of the Screen class. I've seen that the problem could be that you have to put it in a different method, but mine already is. So here's my code:

Snake class:

package snake.graphics; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import java.util.ArrayList; import javax.swing.JPanel; import snake.entities.BodyPart; public class Screen extends JPanel implements Runnable {    private static final long serialVersionUID = 1L;    public static final int WIDTH = 800;    public static final int HEIGHT = 500; // this height should be 800 also but that doesn't fit my screen    private Thread thread;    private boolean running=false;    private BodyPart b;    // array list    private ArrayList <BodyPart> snake;    private int xCoor=10;    private int yCoor=10;    private int size=5;    private boolean right=true;    private boolean left=false;    private boolean up=false;    private boolean down=false;    private int ticks=0;    private Key key;    // constructor    public Screen() {        setFocusable(true);        key = new Key();        addKeyListener((KeyListener) key);        setPreferredSize(new Dimension(WIDTH, HEIGHT));        // initializaing the array list        snake=new ArrayList<BodyPart>();        start();    }    // methods    // tick method    public void tick() {        // if there is nothing in the snake except for its head, make a new bodypart on it        if (snake.size() == 0) {            b=new BodyPart(xCoor, yCoor, 10);            snake.add(b);        }        ticks++;        if (ticks > 250000) {            if (right) {                xCoor++;            }            if (left) {                xCoor--;            }            if (up) {                yCoor--;            }            if (down) {                yCoor++;            }            ticks=0;            b=new BodyPart(xCoor, yCoor, 10);            snake.add(b);            // if the snake size is greater than the size            if (snake.size()  > size) {                // remove one of the body parts                snake.remove(0);            }        }    }    public void paint(Graphics g ) {        // clearing the rectangles so the snake is a constant length of 5        g.clearRect(0, 0, WIDTH, HEIGHT);        // drawing the grid using a for loop        g.setColor(Color.BLACK); // change to MAGENTA        // line for the vertical lines        for (int i=0; i < WIDTH/10; i++) {            g.drawLine(i*10, 0, i*10, HEIGHT);        }        // lines for the horizontal lines        for (int i=0; i < HEIGHT/10; i++) {            g.drawLine(0, i*10, WIDTH, i*10);        }        // for loop for drawing the snake body part        for (int i=0; i < snake.size(); i++) {            snake.get(i).draw(g);        }    }    // method to start the game    public void start() {        running=true;        thread=new Thread(this, "Game Loop");        thread.start();    }    // method to stop the game    public void stop() {        running=false;    }    public void run() {        // main loop        while (running) {            tick();            repaint();        }    }    private class Key implements @KeyListener() {        public void keyPressed(KeyEvent e) {            int key=e.getKeyCode();            if (key == KeyEvent.VK_RIGHT && !left) {                right=true;                up=false;                down=false;            }            if (key == KeyEvent.VK_LEFT && !right) {                left=true;                up=false;                down=false;            }            if (key == KeyEvent.VK_UP && !down) {                up=true;                right=false;                left=false;            }            if (key == KeyEvent.VK_DOWN && !up) {                down=true;                right=false;                left=false;            }        }        public void keyTyped(KeyEvent e) {        }        public void keyReleased(KeyEvent e) {        }    } }

Bodypart class:

package snake.entities; import java.awt.Color; import java.awt.Graphics; public class BodyPart {    private int xCoor;    private int yCoor;    private int width;    private int height;    // constructor    public BodyPart(int xCoor, int yCoor, int tileSize) {        this.xCoor=xCoor;        this.yCoor=yCoor;        width=tileSize;        height=tileSize;    }    public void tick() {    }    public void draw(Graphics g) {        g.setColor(Color.BLACK);        // making the snake        g.fillRect(xCoor * width, yCoor * height, width, height);        // setting the snake's colour to green        g.setColor(Color.GREEN);        g.fillRect(xCoor * width + 2, yCoor * height + 2, width - 4, height-4);    } }

Frame class:

import java.awt.GridLayout; import javax.swing.JFrame; import snake.graphics.Screen; public class Frame extends JFrame {    public Frame() {        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        setTitle("Snake");        setResizable(false);        init();    }    public void init() {        setLayout(new GridLayout(1, 1, 0, 0));        Screen scr=new Screen();        add(scr);        // pack(): whatever is in the window, it makes it that size        pack();        // setLocationRelativeTo(): puts the frame in the middle of the screen        setLocationRelativeTo(null);        setVisible(true);    }    public static void main (String[] args) {        // create a new frame        new Frame();     } }

Thanks in advance for your help!

Hello, I have a few static members exercises due and I wasn't sure if I am doing this correctly. Here is the question:

Create a class named Shirt with data members for collar size and sleeve length.  Include 2 constructors (default and one with both data members) and appropriate set and get methods.  Create a static variable to hold the material type and set it to “cotton”. [Shirt.java].  

Create a TestShirt class with a main method to test the Shirt class.  Create 5 objects of the class. Three will use the default constructor and then the set methods and user input to set the values. The other two will use the overloaded constructors and values that you provide when you instantiate the objects. Output all information for each object.

Here is my code:
public class Shirt { // data members private  int collarSize; private  int sleeveLength; private static String material="Cotton"; // setters and getters public void setCollarSize(int sCollarSize) { collarSize = sCollarSize; } public void setSleeveLength(int sSleeveLength) { sleeveLength = sSleeveLength; } public int getCollarSize() { return collarSize; } public int getSleeveLength() { return sleeveLength; } // constructors public Shirt() { collarSize=10; sleeveLength=20; } public Shirt(int sCollarSize, int sSleeveLength) { collarSize=sCollarSize; sleeveLength=sSleeveLength; } }

Second class:

package Shirts; public class TestShirt { public static void main(String[] args) { // 5 objects Shirt shirt1=new Shirt(); Shirt shirt2=new Shirt(); Shirt shirt3=new Shirt(); Shirt shirt4=new Shirt(); Shirt shirt5=new Shirt(); // first object System.out.println("Shirt 1:\nCollar Size: " + shirt1.getCollarSize() + "\nSleeve Length: " + shirt1.getSleeveLength()); // second object System.out.println("\nShirt 2:\nCollar Size: " + shirt2.getCollarSize() + "\nSleeve Length: " + shirt2.getSleeveLength()); // third object System.out.println("\nShirt 3:\nCollar Size: " + shirt3.getCollarSize() + "\nSleeve Length: " + shirt3.getSleeveLength()); // overloaded constructors for the last two shirt4.setCollarSize(7); shirt4.setSleeveLength(17); System.out.println("\nShirt 4:\nCollar Size: " + shirt4.getCollarSize() + "\nSleeve Length: " + shirt4.getSleeveLength()); // last object shirt5.setCollarSize(6); shirt5.setSleeveLength(22); System.out.println("\nShirt 5:\nCollar Size: " + shirt5.getCollarSize() + "\nSleeve Length: " + shirt5.getSleeveLength()); } }


My questions are:

1. I'm not sure what I should be putting in the default constructor- is it values you give it or just blank?
2. How can I use user input from and set method from the default constructor for the first 3 values? Super confused about that.
3. How can I use overloaded constructors when I instantiate the object for the last two?

Thank you.

Hello,

Ok thank you everyone for your suggestions! The reason why I have extra comments is because my teacher requires us to do so. But this is my code using your suggestions:

public class extrapractise2 { public static void main(String[] args) { // make an array of test scores String testScores[][]= {{"Test 1", "89", "76", "88"}, {"Test 2", "78", "87", "70"}, {"Test 3", "90", "94", "20"}}; System.out.println("Test\tStudent 1\tStudent 2\tStudent 3"); // for loop for rows for (int row=0; row < testScores.length; row++) { // for loop for columns for (int column=0; column < testScores[row].length; column++) { // print the values System.out.print(testScores[row][column] + "\t\t"); } System.out.println(); } } }

OK Thank you! Can you specify what you mean by that? Like this?

public class Class1 { public static void main(String[] args) { // make an array of test scores String testScores[][]= {{"Test 1", "89", "76", "88"}, {"Test 2", "78", "87", "70"}, {"Test 3", "90", "94", "20"}}; // header System.out.println("Test\tStudent1\tStudent2\tStudent3"); // for loop for rows for (int i=0; i < testScores.length; i++) { // for loop for columns for (int k=0; k < testScores[i].length; k++) // print the values System.out.print(testScores[i][k]); } System.out.print("\n"); } }

That gives me this output:

Test Student1 Student2 Student3 Test 1 89 76 88 Test 2 78 87 70 Test 3 90 94 20

Hello,

Yes I forgot to println! Thanks for that. But it still outputs as:

Test 1 89 76 88 Test 2 78 87 70 Test 3 90 94 20

Whereas I want it to be in three rows according to test #.

Hello, I would like to print this out using arrays and for loops:

Test     Student 1     Student 2     Student 3
Test 1      89                 76                88
Test 2      78                 87                70
Test 3      90                 94                20

But my program does not work! It outputs everything side by side, like this:
Test Student1 Student2 Student3 Test 1897688Test 2788770Test 3909420  


This is my program:

public class javaextrapractise { public static void main(String[] args) { // make an array of test scores String testScores[][]= {{"Test 1", "89", "76", "88"}, {"Test 2", "78", "87", "70"}, {"Test 3", "90", "94", "20"}}; // header System.out.println("Test\tStudent1\tStudent2\tStudent3"); // for loop for rows for (int i=0; i < testScores.length; i++) { // for loop for columns for (int k=0; k < testScores[i].length; k++) // print the values System.out.print(testScores[i][k]); } } }


Thank you for your help!

Exception in thread "main" java.lang.Error: Unresolved compilation problems: Type mismatch: cannot convert from float to float[][] The type of the expression must be an array type but it resolved to float at CurrencyProgram.main(CurrencyProgram.java:42)

It gives me the error message above, the code does not run at all

Hello everyone, I've needed help on a program that asks the user for 5 countries, their currency name, the exchange rate and displays it in dollars using arrays. This is my code:

import java.util.Scanner; public class CurrencyProgram { public static void main(String[] args) { Scanner input=new Scanner(System.in); // arrays String [][]array=new String[5][2]; //String []currencyArray=new String[5]; float[][]exchangeRates=new float[5][2]; // variables int row=0; int col=0; int curr=0; // for loops- should go through and ask for country and the corresponding currency for (row=0; row < array.length; row++) { System.out.print("Enter the country: "); array[row][col]=input.next(); for (col=0; col < array[row].length; col++) { System.out.print("Enter the currency: "); array[row][col]=input.next(); } } // for loop for today's exchange rate for (row=0; row < exchangeRates.length; row++) { System.out.print("Enter the exchange rate for " + array[row][col] + ": "); exchangeRates[row][col]=input.nextFloat(); for (col=0; col < exchangeRates[row].length; col++) { exchangeRates=1/exchangeRates[row][col]; } } System.out.println("\nCOUNTRY\tCURRENCY\tEXCHANGE RATE\tFOREIGN CURRENCY IN $"); // for loop to print the result for (row=0; row < array.length; row++) { for (col=0; col < array[row].length; col++) { System.out.print(array[row][col] + "\t"); for (curr=0; curr < exchangeRates.length; curr++) { System.out.print(exchangeRates[row][col][curr] + "\t"); } } } } }


Help is much appreciated. Thank you.

Oh ok thank you! I tried subtracting one so the line for the student is [row-1][col-1] and that seems to give me the correct answer. Yes, there are unnecessary comments as my teacher wants us to comment on at least every other line of code to help us better understand it. I didn't do it in the second part, as I was still tinkering around with it. No, I have not learnt about methods yet! The only problem now is that I'm not sure how to display a message if the student asks for an array which has not been entered.

Wow thank you so much! It means a lot, I really needed the motivation!

Hello,

I have to write a program for two users, a school admin and a student. The admin must first enter a password and enter 15 courses by day Mon-Fri (1-5) and time Morning, Afternoon, Evening (1-3) into an array. Then the student can enter the day and time and view courses available. If the admin has not entered a course for that day, it should display 'Course not available'. This is the code I have:


package pkg; import java.util.Scanner; public class Exercise3 { public static void main(String[] args) { // Scanner Scanner input=new Scanner(System.in); // Array String[][] schedule=new String[5][3]; int row=0; int col=0; String cont=""; // ask user to choose between admin or student System.out.print("Enter A for admin and S for student: "); String user=input.next(); System.out.println("ADMIN"); // ask them to enter the password for admin System.out.println("Enter the password: "); String pass=input.next(); // if they enter the password 'admin' if (pass.equals("admin")) { System.out.print("Welcome, admin!\n\n"); // for loop for (row=0; row < schedule.length; row++) { for (col=0; col < schedule[row].length; col++) { System.out.print(" Enter the course for day " + (row+1) + " and time " + (col+1) + ": "); schedule[row][col]=input.next(); } } } // else password is incorrect else { System.out.println("Incorrect password"); } System.out.println("STUDENT"); do { System.out.print("Enter the day you would like: "); row=input.nextInt(); System.out.print("Enter the time you would like: "); col=input.nextInt(); System.out.print("The course offered at this time is " + schedule[row+1][col+1]); if (schedule[row][col] == 0) { System.out.println("There are no courses offered at that time."); } // reset the row and col row=0; col=0; System.out.print("\nWould you like to quit? Y or N: "); cont=input.next(); } while (cont.equalsIgnoreCase("N")); } }



But I have two problems: when I try to enter a day and time for the student, this error shows up: Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 3 out of bounds for length 3 at pkg.Exercise3.main(Exercise3.java:72)
which I know means my array is out of bounds, but I'm not sure why as I entered numbers like 2 for day and 3 for time! Also, I cannot figure out how to display the message that the 'course is not available' if the array has not been filled.

Any help would be much appreciated! Thanks!

Thank you all for the help! And yes, my teacher requires that we comment on at least every other line of code to make sure we understand what we are doing. And thank you, I will put the square brackets immediately following the type from now on.