I'm currently developing a simple chessboard with Java ACM and I want to fill every second rectangle with a color but I don't know how to.
for (i = 0; i < 400; i += 50) {
for (j = 0; j < 400; j += 50) {
GRect rect = new GRect(100, 100, i, j);
add(rect);
}
}
I tried it with a if statment, but i doesn't worked for me.
With your pretty minimal description, here is my solution.
Here is a tile-able representation. 1/2/3/4 represent "cases"
Assuming: i and j are dimensions of the chessboard, 50x50 is the size of a square.
Assuming: Constructor for GRect is (width, height, ipos, jpos), with top left rectangle coordinate system.
Assuming: Only making rectangles for black squares (cases 2 and 3)
Notice: cases 2 is when (i % 100 == 50) AND (
However, what you probably want is a checker board patter:
for (int i = 0; i < 400; i += 50) {
for (int j = 0; j < 400; j += 50) {
if (i % 100 == 0) {
if (j % 100 == 50) {//case 3
add(new GRect(50,50, i, j));
}
} else if (i % 100 == 50) {
if (j % 100 == 0) { //case 2
add (new GRect(50,50, i, j));
}
}
}
}
Note: no one has any idea what the constructor of GRect is, so i've made my best guess as to what to do.
You could hold an ever switching running condition:
boolean white = true;
for (int i = 0; i < 400; i += 50) {
for (int j = 0; j < 400; j += 50) {
...
white = !white;
Or derive the color from i and j, which then better be [0, 8) indices:
for (i = 0; i < 8; ++i) {
for (j = 0; j < 8; ++j) {
boolean white = (i + j) % 2 == 0;
GRect rect = new GRect(100, 100, i*50, j*50);
rect.setFillColor(white ? Color.WHITE : Color.BLACK);
add(rect);
}
}
Related
So im programming a battleships game, and im trying to place ships on a board. I can get it to place the ship going left and going down from the starting point but cant get it going down or left. I understand my method overall is in-effeicient.
public static int[][] SetUserBoard(int[][] board) {
int x;
int y;
y = 0;
for (int z = 0; z < 10; z++) {
String gridv;
gridv = "";
int direction;
System.out.println("Set the Position for Ship no. " + (z+1));
Scanner s1 = new Scanner(System.in);
System.out.println("Enter the grid column(A-H):");
gridv = s1.nextLine();
if (gridv.equals("A")) {
y = 0;
}
if (gridv.equals("B")) {
y = 1;
}
if (gridv.equals("C")) {
y = 2;
}
if (gridv.equals("D")) {
y = 3;
}
if (gridv.equals("E")) {
y = 4;
}
if (gridv.equals("F")) {
y = 5;
}
if (gridv.equals("G")) {
y = 6;
}
if (gridv.equals("H")) {
y = 7;
}
System.out.println("Enter the y co=ordinate: ");
x = s1.nextInt();
x -= 1;
System.out.println("Enter the direction of the ship 0-3(0=down,1=right,2=up,3=left): ");
direction = s1.nextInt();
if(z == 0) { //placing 4 unit ship in first increment
if(direction == 0 && x < 5){ //vertical placement - down
for(int i=0; i < 4; i++) {
board[x][y] = 0;
x += 1;
}
}
if(direction == 1 && y < 5) { //horizontal placement - right
for(int i=0; i < 4; i++) {
board[x][y] = 0;
y += 1;
}
}
if(direction == 2 && x > 3 ) { //vertical placement - up
for(int i=0; i < 4; i++) {
board[x][y] = 0;
x -= 1;
}
}
if(direction == 3 && y > 3) { //horizontal placement - left
for(int i=0; i < 4; i++) {
board[x][y] = 0;
y -= 1;
}
}
}
...if(z > 0 && z < 3) { //placing 3 unit ships in 2nd and 3rd increment....
return board;
}
if you ignore the bottom part, and focus on the if z=0 part as that's which part i'm using to test this with my most updated try. Originally I had an indexing error which I managed to solve but now all the program does is run as usual except when moving onto the next one the board isn't updated and is still empty. So im stumped as to what logic to use for up/left.
For diagonal changes, you need to alter both i and j as you traverse the ship. For instance:
UP_LEFT = 4
...
ship_len = 4
...
if(direction == UP_LEFT &&
y > ship_len-1 &&
x > ship_len-1) { // SE-NW placement
for(int i=0; i < ship_len; i++) {
board[x][y] = 0;
y -= 1;
x -= 1;
}
}
public static Color[][] dilate(Color[][] array) {
boolean white = false;
boolean black = false;
Color[][] copy = new Color[array.length][array[0].length];
for(int i = 0; i<array.length; i++){
for(int j=0; j<array[i].length; j++){
int g = array[i][j].getGreen();
if( g>= 0 && g< 50){
black = true;
//System.out.println("black is true");
} else if(g> 200 && g < 300){
white = true;
//System.out.println("white is true");
} else {
System.out.println("Nothing");
}
if (white == true){
//System.out.println("who");
for(int x = i-3; x <= i + 3; x++){
//int rem = k - Math.abs(i - x);
for(int y = j- 3; y<= j + 3; y++){
if (x>=0 && y>=0 && x < array.length && y < array[0].length && black == true){
copy[x][y] = new Color(255, 255, 255);
}
}
}
}
}
}
return copy;
}
So i'm trying to dilate a binary image. I take a white pixel from the Color array, and create a threshold. If within that threshold I find any any black pixel, i make it white and store those into another array. I can't figure out why my resulting image is all white.
I have been given the task of writing a script to "erode" a binary image i.e. black and white photo.
This means that I must distinguish the parts that are white from black, where on an RGB scale, black is 0 and 1 is white.
Pixels are iterated over on a horizontal (i index) and vertical (j index). In order for a pixel to be considered a particular colour, it's immediate neighbours must be of that colour i.e. i+1 and i-1 and j+1 and j-1.
My attempt to code this is as follows:
public static BufferedImage getErodedImage(BufferedImage image) {
BufferedImage target = copyImage(image);
for (int i = 0; i < image.getRaster().getWidth(); i++) {
for (int j = 0; j < image.getRaster().getHeight(); j++) {
if (i + 1)||(i - 1) == 0 {
i = 0
}
else{
i = 1
}
}
if (j + 1)||(j - 1) == 0 {
j = 0
}
else{
j = 1
}
}
}
My attempt is very pythonic and returns lots of Errors and I'm guessing that I might need another for loop to iterate the -1, 0 and +1 values. and then set the value of the i-th pixel.
In your code a lot of syntax error, try to use this code:
public static BufferedImage getErodedImage(BufferedImage image) {
BufferedImage target = copyImage(image);
for (int i = 0; i < image.getRaster().getWidth(); i++) {
for (int j = 0; j < image.getRaster().getHeight(); j++) {
if (i + 1 == 0 || i - 1 == 0) { // not if (i + 1)||(i - 1) == 0
i = 0; // ;
}
else{
i = 1; // ;
}
if (j + 1 == 0 ||j - 1 == 0) { // not if (j + 1)||(j - 1) == 0 and this "if" should be in "for (int j..."
j = 0; // ;
}
else{
j = 1; // ;
}
}
}
}
trying to create a Conways Game of life, but apparently the shapes are not like they have to be. Perhaps someone can help me find the issue.
For example the glider :
- X - - - -
- - X X - -
- X X - - -
- - - - - -
becomes this
- - X X - -
- X - - - -
X X X - - -
- X X X - -
but should be like this :
- - X - - -
- - - X - -
- X X X - -
- - - - - -
And my code looks like this
public Frame(int x, int y) {
setWidth(x);
setHeight(y);
if (x<1)
frame = null;
else if (y<1)
frame = null;
else {
frame = new String [x][y];
for (int i=0; i<frame.length; i++) {
for (int j=0; j<frame[i].length; j++) {
frame [i][j] = DEAD;
}
}
} // else
} // construktor
public Integer getNeighbourCount(int x, int y) {
Frame cell = new Frame(getHeight(), getWidth());
int counter = 0;
if(frame[x][y].equals(ALIVE))
{
counter = counter - 1;
}
for(int i=x-1; i<=x+1;i++){
if(i<frame.length && i>0){
for(int j=y-1; j<=y+1;j++){
if(j<frame[i].length && j>0){
if (frame[i][j]==ALIVE) {
counter++;
}
}
}
}
}
return counter;
}
public Frame nextFrame() {
// Returns next frame
Frame cell = new Frame(getWidth(), getHeight());
//cell.frame = new String[getWidth()][getHeight()];
for(int i = 0; i < frame.length; i++){
for(int j =0; j <frame[i].length;j++){
int n = getNeighbourCount(i,j);
if(cell.frame[i][j]==null) {
cell.frame[i][j] = DEAD;
}
if (isAlive(i, j) && n < 2 || n > 3) {
cell.frame[i][j] = DEAD;
}
if (isAlive(i, j) && n == 3 || n == 2){
cell.frame[i][j] = ALIVE;
}
if(!isAlive(i, j) && n == 3) {
cell.frame[i][j] = ALIVE;
}
if(isAlive(i, j) && n > 3){
cell.frame[i][j] = DEAD;
}
frame[i][j] = cell.frame[i][j];
}
}
cell.toString();
return cell;
}
`
Full code http://pastebin.com/LMwz724H
Here's a solution that works - using an enum for each cell and getting the i/j and x/y stuff right (I think). It certainly generates the correct first iteration:
static class GameOfLife {
final int w;
final int h;
State[][] frame;
enum State {
Dead, Alive;
}
public GameOfLife(int w, int h) {
this.w = w;
this.h = h;
frame = new State[h][w];
}
public void alive(int x, int y) {
frame[y][x] = State.Alive;
}
public void tick() {
frame = nextGeneration();
}
private int surroundingPopulation(int x, int y) {
int pop = 0;
for (int i = y - 1; i <= y + 1; i++) {
for (int j = x - 1; j <= x + 1; j++) {
// On frame - vertically.
if ((i >= 0 && i < h)
// On frame horizontally.
&& (j >= 0 && j < w)
// Alive
&& (frame[i][j] == State.Alive)
// Not the center.
&& (i != y || j != x)) {
pop += 1;
}
}
}
return pop;
}
private State[][] nextGeneration() {
State[][] next = new State[h][w];
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
int pop = surroundingPopulation(x, y);
// Any live cell
if (frame[y][x] == State.Alive) {
if (pop < 2) {
// ... with fewer than two live neighbours dies, as if caused by under-population.
next[y][x] = State.Dead;
} else if (pop > 3) {
// ... with more than three live neighbours dies, as if by overcrowding.
next[y][x] = State.Dead;
} else {
// ... with two or three live neighbours lives on to the next generation.
next[y][x] = State.Alive;
}
} else {
// Any dead cell with exactly three live neighbours becomes a live cell, as if by reproduction.
if (pop == 3) {
next[y][x] = State.Alive;
}
}
}
}
return next;
}
#Override
public String toString() {
StringBuilder s = new StringBuilder();
for (State[] row : frame) {
for (State c : row) {
s.append(c == State.Alive ? "X" : " ");
}
s.append("\r\n");
}
return s.toString();
}
}
public void test() {
GameOfLife g = new GameOfLife(6, 6);
g.alive(1, 0);
g.alive(2, 1);
g.alive(3, 1);
g.alive(1, 2);
g.alive(2, 2);
System.out.println("Before:\r\n" + g);
g.tick();
System.out.println("After:\r\n" + g);
}
I believe the problem is that you are copying the new value as you iterate through the loop. This means neighbours are using the value from the next tick rather than the current one.
You can fix this by waiting until you calculated all new values in your new frame: cell.frame and then iterate through the frame again and copy from cell.frame to frame.
An alternative (better in my view) is to have away of cloning a frame during construction. Then you could change your nextFrame method to create a clone of frame and use the clone to set the new values in frame.
You are changing the DEAD and ALIVE frames while you iterate through the grid. You need to store the coordinates which should die or become alive and perform that afterwards.
Store the coordinates in two ArrayLists (dead, alive). The first and second position is the x and y axis, and change those coordinates according to whether they should become alive or not.
Here's a snippet from a simple test I wrote a while back. As others have mentioned, don't change values on an active board while still reading them. Instead, clone the board and make changes to the copy while reading the current board.
Another problem I bumped into a few times was iterating over y, then x for each y, but referring to x,y when accessing a point. It feels back to front :)
// Rules:
// 1) Any live cell with fewer than two live neighbours dies, as if caused by under-population.
// 2) Any live cell with two or three live neighbours lives on to the next generation.
// 3) Any live cell with more than three live neighbours dies, as if by overcrowding.
// 4) Any dead cell with exactly three live neighbours becomes a live cell, as if by reproduction.
void mutateGrid() {
// Copy existing grid into the next generation's grid
boolean[][] mutatedGrid = new boolean[gridXWidth][gridYHeight];
for (int i = 0; i < gridXWidth; i++) {
System.arraycopy(grid[i], 0, mutatedGrid[i], 0, gridYHeight);
}
// Start mutation rules
for (int y = 0; y < gridYHeight; y++) {
for (int x = 0; x < gridXWidth; x++) {
int liveNeighbours = countLiveNeighbours(x,y);
if (liveNeighbours < 2 || liveNeighbours > 3) {
mutatedGrid[x][y] = false;
}
else if (liveNeighbours == 3) {
mutatedGrid[x][y] = true;
}
}
}
grid = mutatedGrid;
}
int countLiveNeighbours(int x, int y) {
int count = 0;
for (int j = y-1; j <= y+1; j++) {
for (int i = x-1; i <= x+1; i++) {
if (i < 0 || j < 0 || i >= gridXWidth || j >= gridYHeight){
continue;
}
if (grid[i][j]) {
count++;
}
}
}
count -= grid[x][y]?1:0; // remove self from count
return count;
}
I am writing a bouncing ball class (I'm just starting to use Java) and it works but it looks like every time the ball hits an edge the containing box gets bigger
Code for the bounce trigger
int i = 0;
int j = 0;
int k = 0;
double x = 3;
double y = 3;
while(i < 200){
if(j == 0){
x += 2;
} else {
x -= 2;
}
if(k == 0){
y += 4;
} else {
y -= 4;
}
if(thisEye.getX() > 400){
j = 1;
}
if(thisEye.getX() < 0) {
j = 0;
}
if(thisEye.getY() > 200){
k = 1;
}
if(thisEye.getY() < 0) {
k = 0;
}
Color someShade = rGen.nextColor(); // var for the color of the eyes
Color someOtherShade = rGen.nextColor();// var for the color of the pupules
moveThis(thisEye,x,y,someShade); // Go over all the shapes with the same X,Y offset - var x,y
moveThis(thisPupul,x,y,someOtherShade);
moveThis(thisEye2,x,y,someShade);
moveThis(thisPupul2,x,y,someOtherShade);
moveThis(face,x,y,rGen.nextColor());
moveThis(nose,x,y,rGen.nextColor());
pause(150.0); // wait for next cycle to slow down the images
//i++; this was to see if it just got farther off with each loop, it dose.
}
}
private void moveThis(GOval subject, double x, double y, Color newShade){
subject.setFillColor(newShade);
subject.move(x, y);
}
the 'face' will bounce off the right spot once then each time it bounces it gets farther and farther off the screen tell is so far of the it only is on screen for a short time then off the other side tell it comes back on screen for a bit.
I marked it as home work but I'm a html/php coder in the day and am just using the iTunesU Stanford videos at night.
but I'm trying to learn so pointers would be great.
The problem could be (though very unlikely) with your theEye.getX() and theEye.getY() method. What if you change your boundary condition check from
if(thisEye.getX() > 400){
j = 1;
}
if(thisEye.getX() < 0) {
j = 0;
}
if(thisEye.getY() > 200){
k = 1;
}
if(thisEye.getY() < 0) {
k = 0;
}
TO
if(x > 400){
j = 1;
}
if(x < 0) {
j = 0;
}
if(y > 200){
k = 1;
}
if(y < 0) {
k = 0;
}
Otherwise, please post the complete source code so we can see where else could the problem be.