3D Heightmap Generator

package com.arkazex.terrain.HGEN2;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Random;
import java.util.Scanner;

import javax.imageio.ImageIO;

public class Main {

    private static long seed;
    private static long seed2;
    private static int mshift;
    private static int dimx;
    private static int dimy;

    private static int[][] map;
    private static long[] seeds;
    private static int[] offset;

    public static void main(String[] args) {
        //Collect values
        Scanner in = new Scanner(System.in);
        System.out.print("Enter first seed: ");
        seed = in.nextLong();
        System.out.print("Enter second seed: ");
        seed2 = in.nextLong();
        System.out.print("Enter Maximum shift: ");
        mshift = in.nextInt();
        System.out.print("Enter dimension X: ");
        dimx = in.nextInt();
        System.out.print("Enter dimension Y: ");
        dimy = in.nextInt();

        map = new int[dimx][dimy];
        seeds = new long[dimy];
        offset = new int[dimy];

        System.out.println("Generating seed map...");
        generateSeeds();

        System.out.println("Generating initial terrain...");
        generateInitialTerrain();

        System.out.println("Generating offsets...");
        generateStartingOffset();

        System.out.println("Generating layers...");
        for(int i = 1; i < dimy; i++) {
            generateLayer(i);
        }

        System.out.println("Finishing...");
        finish();

        in.close();
        System.out.println("Complete!");
    }

    private static void generateSeeds() {
        Random rand = new Random(seed);
        for(int i = 1; i < dimy; i++) {
            seeds[i] = rand.nextLong();
        }
    }

    private static void generateInitialTerrain() {
        int last = 0;
        Random rand = new Random(seed2);
        map[0][0] = 0;
        for(int i = 0; i < dimx; i++) {
            int off = rand.nextInt(mshift);
            boolean flip = rand.nextBoolean();
            if(flip) {
                off = 0 - off;
            }
            last = last + off;
            if(last > 255) {
                last = 255;
            }
            if(last < 0) {
                last = 0;
            }
            map[i][0] = last;
        }
    }

    private static void generateStartingOffset() {
        int last = 0;
        Random rand = new Random(seeds[0]);
        for(int i = 0; i < dimy; i++) {
            int off = rand.nextInt(mshift);
            boolean flip = rand.nextBoolean();
            if(flip) {
                off = 0 - off;
            }
            last = last + off;
            if(last > 255) {
                last = 255;
            }
            if(last < 0) {
                last = 0;
            }
            offset[i] = last;
        }
    }

    private static void generateLayer(int x) {
        int last = offset[x];
        int res = 0;
        Random rand = new Random(seeds[x]);
        for(int i = 0; i < dimx; i++) {
            boolean valid = false;
            while(!valid) {
                int off = rand.nextInt(mshift);
                boolean flip = rand.nextBoolean();
                if(flip) {
                    off = 0 - off;
                }
                res = last + off;
                if(!(res > map[i][x - 1] + mshift || res < map[i][x - 1] - mshift)) {
                    valid = true;
                }
            }

            last = res;

            if(last > 255) {
                last = 255;
            }
            if(last < 0) {
                last = 0;
            }
            map[i][x] = last;
        }
    }

    private static void finish() {
        BufferedImage image = new BufferedImage(dimx, dimy, BufferedImage.TYPE_INT_RGB);
        for(int x = 0; x < dimx; x++) {
            for(int y = 0; y < dimy; y++) {
                image.setRGB(x, y, getRGB(map[x][y]));
            }
        }
        File file = new File("Output.png");
        try {
            file.createNewFile();
            ImageIO.write(image, "png", file);
        } catch (IOException e) {
            System.out.println("Failed to save image");
        }
    }

    private static int getRGB(int value) {
        String raw = null;
        try {
            String hex = Integer.toHexString(value);
            if(hex.length() == 1) {
                hex = 0 + hex;
            }
            raw = "0xFF" + hex + hex + hex;
        } catch (Exception e) {
        }
        return castLong(Long.decode(raw));
    }

    public static int castLong(long value) {
        return (int) value;
    }
}