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How to do smooth-scrolling by Java robot?

I got used to my touch pad, that allows to scroll smoothly and very exactly, but I can not to simulate it by Java robot - mousewheel is getting only integer parameters and a scrolling carried by steps. Can I simulate smoothly scrolling in Java?
robot.mouseWheel(a); // int a

The unit of scrolls will always be by "notches of the wheel" (before you ask: that's how the measurement is named in the docs). This is simply how it's implemented by the hardware (to be more specific: the mouse). How many pixels are scrolled per "notch" is nothing but OS-configuration. You can't mess with that with pure java and I wouldn't recommend it, even if it was possible.
What you can do nevertheless is to slow down the speed at which the robot scrolls:
import java.awt.Robot;
public class Test{
public static void main(String[] args)
throws Exception
{
//time to switch to a specific window where the robot ought to be tested
try{ Thread.sleep(2000); }catch(InterruptedException e){}
Robot r = new Robot();
for(int i = 0; i < 20; i++){
//scroll and wait a bit to give the impression of smooth scrolling
r.mouseWheel(1);
try{ Thread.sleep(50); }catch(InterruptedException e){}
}
}
}

FRC Java Mecanum Drive

I am the programmer for my FRC Team 4468 and we are using mecanum wheels this year. We are trying to control the robot with two joysticks, one for moving in a direction (mecStick), and another for rotation (rotStick) using this line of code.
myDrive.mecanumDrive_Cartesian(mecStick.getX(), mecStick.getX(), rotStick.getY(), 0);
The robot will move in the Y direction (fowards, backwards), and will rotate but won't move in the X axis. Could someone tell me what i'm doing wrong please.
Thanks :-)
public class RobotTemplate extends SimpleRobot {
RobotDrive myDrive = new RobotDrive(1,2,3,4);
Joystick mecStick = new Joystick(1);
Joystick rotStick = new Joystick(2);
public void robotInit() {
}
public void autonomous() {
}
public void operatorControl() {
//myDrive.setSafetyEnabled(true);
myDrive.mecanumDrive_Cartesian(mecStick.getX(), mecStick.getX(), rotStick.getY(), 0);
Timer.delay(0.01);
}
}

Looks like you pass mecStick.getX() twice, one should probably be mecStick.getY(). I'm not familiar with the RobotDrive class, so I'm not sure which should be switched. The WPILib Javadoc is your friend, you can find a copy hosted by team 2168 at http://team2168.org/javadoc/. Look for RobotDrive on the left bottom list, and check there.
Best of luck from 1902, Exploding Bacon!

Slick2d, How can i draw a string on screen for a few seconds?

I've been trying to figure this out, all I want to do is be able to draw a string for longer than just a frame, but when I call it in the method I want it to flash up then disappear immediately, any advice would be appreciated :) I'm using something like this:
g.drawString("You got a Key!", 100, 100);
I'm doing this in a method which is called after an Item is picked up
public void addItemFound(Graphics g){
ip.mainInventory[ip.getFirstEmptyStack()] = getItemStackFound();
System.out.println(this.getItemFound() + " added");
g.drawString("You Got a Key!", 100, 100);
}
That's the full method if you were interested :) Thanks!Also apologies for the dumb question, i'm a newbie to this :P

I believe that the best way to do this project would be to draw the scene at regular intervals e.g. 10 milliseconds using a Thread.sleep(). This way, you can simply add a variable to show the message for, say, 100 loops (1 second) like this:
private LinkedList<String> drawStringList= new LinkedList<>();
private LinkedList<Integer> drawStringTimeout= new LinkedList<>();
private LinkedList<Integer[]> drawStringPos= new LinkedList<>();
public void addText(String stringToWrite, int posX, int posY, int timeOut) {
drawStringList.add(stringToWrite);
int[] pos = new int[2];
pos[0] = posX;
pos[1] = posY;
drawStringPos.add(pos);
drawStringTimeout.add(timeOut);
}
private void mainLoop() {
...items to be drawn here...
for(int i=0;i<drawStringList.size();i++){
g.drawString(drawStringList.get(i),drawStringPos.get(i)[0],drawStringPos.get(i)[1]);
drawStringTimeout.set(i,drawStringTimeout.get(i)-1);
if(drawStringTimeout.get(i)<=0) {
drawStringList.remove(i);
drawStringTimeout.remove(i);
drawStringPos.remove(i);
}
}
try { Thread.sleep(10); } catch (Exception e) {}
}
In this code, you must add the string you want to draw to drawStringList, add the number of loops you want it to stay for to drawStringTimeout and add the position you would like to draw it in to drawStringPos as an array (you could use a point if you wanted to). I have made a method to do this.

I don't know what Dan300 is trying to tell you to do but that's way, way, way over complicated. Slick2D works on gamestates:
http://slick.ninjacave.com/javadoc/org/newdawn/slick/state/GameState.html
The gamestate has a method called render(). The render() is called every single cycle of the loop to update your screen with drawing information. If you want to draw the text on the screen for a longer time you should be drawing the text somewhere within the stack space of this render() function.
What is happening now is you have a function with one specific purpose that only exists every so briefly: add an item to the player. The game comes across this statement and when adding an item within that 1 cycle the text will be drawn. But the next cycle when the player isn't picking up an item it won't come by that drawString statement and you won't have your string on your screen longer than 1 game cycle.

Java Swing Frame crashes upon opening?

I am programming a chess game in java, and at the moment I am building a basic interface. It is simply an 8x8 array of buttons that will display in a window. I have coded for these buttons, and have gotten the board to display properly. However, when I connect this with the rest of the game, the game window crashes upon running and I have to force quit the java application. This is my code:
package Chess_Game;
import javax.swing.SwingUtilities;
import Chess_Interface.Iboard;
public class Game_Tester
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
Game G = new Game();
Iboard I = new Iboard(G.getBoard().getArray(), G.getSides());
I.setVisible(true);
while(!(G.isGameOver()))
{
boolean redo = true;
while(redo)
{
int row = 0;
int col = 0;
int nRow = 0;
int nCol = 0;
System.out.println("Click the piece you want to move.");
while(!(I.getBool())){}
if(I.getBool())
{
row = I.getRow();
col = I.getCol();
I.setBool(false);
}
System.out.println("Click the place you want to move to.");
while(!(I.getBool())){}
if(I.getBool())
{
nRow = I.getRow();
nCol = I.getCol();
I.setBool(false);
}
if(G.canMove(row, col, nRow, nCol))
{
G.move(row, col, nRow, nCol, I);
redo = false;
}
else
{
System.out.println("You cant move there! Try again!");
}
}
I.updateBoard(G.getBoard().getArray(), G.getSides());
}
}
});
}
}
The board displays properly when I comment out the main while loop (and everything inside of it), and I assume the problem lies somewhere inside there, but I have been unable to find it. I have also looked online for similar game loop problems, but all of those have been for games involving frame rates and movement across a java swing frame, something that is not present in my code.
Any help would be greatly appreciated.

You have several loops such as
while(!(I.getBool())){}
which could potentially run forever if I does not respond as expected. You could start by printing something out within these loops, and within the following blocks if(I.getBool()){...} to see at what point your application gets stuck.
Checking the user interface in a loop like this is not good practice. It is better to use Listeners to respond to the user interface.
Nor is running the main application on the Swing thread using SwingUtilities.invokeLater(new Runnable(), even though it avoids potential problems of updating the GUI from another thread.
In fact, this may be your root problem, as running the main application loop on the Swing thread (the thread used to run the GUI) like this probably prevents the GUI from ever responding properly. You are putting a task (the entire game) onto the GUI's queue, but that task never completes while(!(G.isGameOver())).

How do I go about making this Conways Life program in java

I am making a Conway's Game of Life program in java, and am trying to change it from the command line version to a GUI. From the command line I just printed an array which showed the generations (the objects such as blocks and blinkers are shown as a series of 1's and 0's where it is blank, and in the GUI I'm showing it as squares (white squares as blank and blue squares where it isn't). But where I'm getting stuck is when I make another method (which replaces the method which prints the array) which checks the grid array, if there is a zero then the square changes from white to blue, and vice-versa. The Conway's Life rules are dealt with in a separate class which is independent, and all this method does is after the rules have changed the array this method checks it.
The rules are done in methods in one class and the GUI components are done in another. But since I need instance of both how would I go about doing it?, merge the two classes (all the GUI classes into the Life one, embed them some how, I am completely stuck on what to do
public void runGUI() {
int x = getX(), y = getY();
x /= squareSize;
y /= squareSize;
for (int i = 0; i < LifeData.grid.length; i++) {
for (int j = 0; j < LifeData.grid[i].length; j++) {
if (LifeData.grid[i][j] == 0)
l.setCell(x, y, l.getCell(x, y) + 1);
else
l.setCell(x, y, l.getCell(x, y) - 1);
this.repaint();
}
}
}
That is what I have changed it to now but when compiling it is saying "non-static variable grid cannot be referenced from a static context" and "non-static method runGUI() cannot be referenced from a static context". When trying to run the method.

Make a separate thread that will execute the game of life and update the GUI.
Something like this
public class GameExecutor implements Runnable {
private static final int DELAY = 1000;
private GameOfLife game;
private boolean stop = false;
private Gui gui;
public GameExecutor(Gui gui, GameOfLife game) {
this.gui = gui;
this.game = game;
};
public void run(){
game.start();
while (!stop) {
game.step(); //execute a step
gui.update(game.getState());
try {
Thread.sleep(DELAY);
} catch (InterruptedException e) {}
}
}
}
Launch this in a thread at startup and pass it your gui. Don't forget to update the gui in the correct Swing thread.
Obviously you'll need to add some code to stop it, too :)