Java reusing methods to generate random position. Okay so my program is creating
ID: 3884156 • Letter: J
Question
Java reusing methods to generate random position.
Okay so my program is creating a 2D array fish tank (8 rows, 32 columns) filled with tilde (~) characters with 4 randomly generated positions of fish ( ><))'> ), 6 pieces of fish good (*) and a hook (J). My code so far has the fish, but I am still trying to find out how I can reuse the generateRandomPositions() method to generate myself the fish food and hook. I have // the parts I thought I would need to add in order to do this.
import java.util.Random;
public class Main {
public static void main(String[] args) {
char [][] tilde = new char [8][32];
fillTank(tilde, '~');
int fish [][] = generateRandomPositions(4, 8, 32);
for (int i = 0; i < fish.length; ++i) {
placeFishInTank(tilde, fish[i][0], fish[i][1]);
}
renderTank(tilde);
System.out.println();
moveAllFish(fish, tilde[0].length, tilde.length);
fillTank(tilde, '~');
System.out.println();
for (int i = 0; i < fish.length; ++i) {
placeFishInTank(tilde, fish[i][0], fish[i][1]);
}
renderTank(tilde);
// int fishHook [][] = generateRandomPositions(1, 8, 32);
// int fishFood [][] = generateRandomPositions(6, 8, 32);
}
/**
* Copies the water character into every position in the tank array. The two-dimensional tank
* array can have dimensions of any size(s).
*
* @param tank will contain all water characters after this method is called.
* @param water is the character copied into the tank.
*/
public static void fillTank(char[][] tank, char water)
{
for (int row = 0; row < tank.length; ++row) {
for (int column = 0; column < tank[row].length; ++column) {
tank [row][column] = '~';
}
System.out.println();
}
}
public static void placeFishInTank(char [][] positionInTank, int x, int y)
{
positionInTank[x][y] = '>';
String fishBody = "><))'";
char[] fishBodyArray = fishBody.toCharArray();
int j = 4;
for (int i = y - 1; i >= 0 && j >= 0; i--) {
positionInTank[x][i] = fishBodyArray[j];
j--;
}
}
/**
* Prints the contents of the tank into the console in row major order, so that the
* smallest row indexes are on top and the smallest column indexes are on the left. For
* example:
* tank[0][0] tank[0][1] tank[0][2] ...
* tank[1][0] tank[1][1] tank[1][2] ...
* ...
* Each row is on its own line, and this method should work for two-dimensional tanks with
* dimensions of any size.
*
* @param tank contains the characters that will be printed to the console.
*/
public static void renderTank(char[][] tank)
{
for (int row = 0; row < tank.length; ++row) {
for (int column = 0; column < tank[row].length; ++column) {
System.out.print(tank[row][column]);
}
System.out.println();
}
}
public static int[][] generateRandomPositions(int number, int width, int height)
{
int [][] fish = new int [number][2];
for (int i = 0; i < number; ++i) {
fish [i][0] = Utility.randomInt(width);
fish [i][1] = Utility.randomInt(height);
}
return fish;
// int [][] fishHook = new int [number][2];
// for (int i = 0; i < number; ++i) {
// fish [i][0] = Utility.randomInt(width);
// fish [i][1] = Utility.randomInt(height);
// }
// return fishHook;
// int [][] fishFood = new int [number][2];
// for (int i = 0; i < number; ++i) {
// fish [i][0] = Utility.randomInt(width);
// fish [i][1] = Utility.randomInt(height);
// }
// return fishFood;
//
}
public static void moveAllFish(int[][] fish, int width, int height) {
for (int i = 0; i < fish.length; i++) {
fish[i][1] = (fish[i][1] + 1) % width;
}
}
}
Explanation / Answer
// int fishHook [][] = generateRandomPositions(1, 8, 32);
// int fishFood [][] = generateRandomPositions(6, 8, 32);
The wa you are calling is absolutely fine. For fish-hook, it would return 1 hook co-ordinates, for food, it would return 6 co-ordinates - similar to how it returned 4 co-ordinates for the fish.
You can use the following body of generateRandomPositions() in order to make this work. It is almost same to yours, just that I have changed the random number generation method, and named the variable to generic ones (because the same variable can return fish, food and hook co-ordinates; based on how you are calling the method).
public static int[][] generateRandomPositions(int numberOfPositions, int width, int height)
{
int [][] randomPositions = new int [number][2];
Random random = new Random();
for (int i = 0; i < number; ++i) {
randomPositions[i][0] = random.nextInt(width); // i.e. return an x co-ordinate from 0 to width-1 range
randomPositions[i][1] = random.nextInt(width); // i.e. return an y co-ordinate from 0 to height-1 range
}
return randomPositions;
}
Please let me know in comments if you have any further question/clarification. Thank you.
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