How to generate biomes in spigot plugin

I have a question about how to generate random biomes in the world with random sizes and hills.

For example, if i have biome plains, and max noise height is 8 and in biome mountains, the max noise height is 64 and the transition between these biomes would smooth.

I already have code and this code generates biome square and transitions between biomes not smooth :/

Main:

public class Generator extends ChunkGenerator {

SimplexOctaveGenerator simplexOctaveGenerator;

public Generator(long seed) {
    simplexOctaveGenerator = new SimplexOctaveGenerator(seed,16);
    simplexOctaveGenerator.setScale((double) 1/100);

}

@Override
public ChunkData generateChunkData(World world, Random random, int x, int z, BiomeGrid biome) {


    ChunkData chunk = createChunkData(world);

    int worldX = x * 16;
    int worldZ = z * 16;
    for(int i = worldX; i < worldX + 16; i++) {
        int chunkX = i - worldX;
        for(int j = worldZ; j < worldZ + 16; j++) {
            int chunkZ = j - worldZ;



            double noise = simplexOctaveGenerator.noise(i,j,0.2F,0.2F,true);

            Material toPlace = null;

            SimplexNoiseGenerator temperatureNoise = new SimplexNoiseGenerator(world.getSeed());
            SimplexNoiseGenerator humidityNoise = new SimplexNoiseGenerator(world.getSeed() + 1);
            SimplexNoiseGenerator heightNoise = new SimplexNoiseGenerator(world.getSeed() + 2);

            double temperature = temperatureNoise.noise(i / 100, j / 100);
            double humidity = humidityNoise.noise(i / 100, j / 100);
            double height = heightNoise.noise(i / 80,j / 100);

            for(int k = 0; k < world.getMaxHeight(); k++) {
                biome.setBiome(chunkX, k, chunkZ, BiomeGen.getBiome(temperature, humidity, height));
                Biome biom = biome.getBiome(chunkX, k, chunkZ);
                if(biom == Biome.DESERT) {
                    int y = (int) (noise * 4 + 100);
                    if (k <= 150 && k > y) {
                        toPlace = Material.AIR;
                    } else if (k > y) {
                        toPlace = Material.AIR;
                    } else if (k == y) {
                        toPlace = Material.GRASS_BLOCK;
                    } else if (k < y) {
                        toPlace = Material.STONE;
                    } else {
                        toPlace = Material.AIR;
                    }
                } else {
                    int y = (int) (noise * 16 + 100);
                    if (k <= 150 && k > y) {
                        toPlace = Material.AIR;
                    } else if (k > y) {
                        toPlace = Material.AIR;
                    } else if (k == y) {
                        toPlace = Material.GRASS_BLOCK;
                    } else if (k < y) {
                        toPlace = Material.STONE;
                    } else {
                        toPlace = Material.AIR;

                    }
                }
                chunk.setBlock(chunkX, k, chunkZ, toPlace);
            }
        }

    }

    return chunk;
}
}

BiomeGen:

   public static  Biome getBiome(double temperature, double humidity, double height) {
    if (temperature < -0.5) {
        // Frozen
        if (humidity < 0) {
            // Frozen and dry
            if (height < -0.5) {
                return Biome.FROZEN_OCEAN;
            } else if (height < 0.3) {
                return Biome.SNOWY_TUNDRA;
            } else {
                return Biome.SNOWY_MOUNTAINS;
            }
        } else {
            // Frozen and wet
            if (height < -0.5) {
                return Biome.FROZEN_OCEAN;
            } else if (height < 0.3) {
                return Biome.SNOWY_TAIGA;
            } else {
                return Biome.SNOWY_TAIGA_MOUNTAINS;
            }
        }
    } else if (temperature < 0) {
        // Cold
        if (humidity < 0) {
            // Cold and dry
            if (height < -0.5) {
                return Biome.COLD_OCEAN;
            } else if (height < 0.3) {
                return Biome.MOUNTAIN_EDGE;
            } else {
                return Biome.MOUNTAINS;
            }
        } else {
            // Cold and wet
            if (height < -0.5) {
                return Biome.COLD_OCEAN;
            } else if (height < 0.8) {
                return Biome.TAIGA;
            } else {
                return Biome.TAIGA_MOUNTAINS;
            }
        }
    } else if (temperature < 0.5) {
        // Normal
        if (humidity < 0) {
            // Normal and dry
            if (height < -0.5) {
                return Biome.OCEAN;
            } else if (height < 0.3) {
                return Biome.PLAINS;
            } else {
                return Biome.WOODED_HILLS;
            }
        } else {
            // Normal and wet
            if (height < -0.5) {
                return Biome.OCEAN;
            } else if (height < 0.3) {
                return Biome.BIRCH_FOREST;
            } else {
                return Biome.TALL_BIRCH_HILLS;
            }
        }
    } else {
        // Hot
        if (humidity < 0) {
            // Hot and dry
            if (height < -0.5) {
                return Biome.DESERT_LAKES;
            } else if (height < 0.3) {
                return Biome.DESERT;
            } else {
                return Biome.DESERT_HILLS;
            }
        } else {
            // Hot and wet
            if (height < -0.5) {
                return Biome.OCEAN;
            } else if (height < 0.3) {
                return Biome.JUNGLE;
            } else {
                return Biome.JUNGLE_HILLS;
            }
        }
    }
}

Screen:

Please help me :)