在Java中创建24位RGB ppm图像

Question

任务是创建24位RGB ppm图像并将其存储在字节数组中。看起来很简单，我用jpg做到了，并且在第一次尝试中就正确了。 ppm虽然似乎没有复制到文件，但文件已创建但为空。我将其从FileOutputStream更改为BufferedWriter，但还是一无所有。

这是代码：

public class test
{

   private static int width = 100;
   private static int height = 100;
   private static String matrix="";



    public static void main (String[]args) {

        matrix +="P6\t" + width + "\t" + height + "\t255\t";

        for (int x=0; x<=height; x++) {
            for ( int y=0; y<=width; y++) {
                int  R = (int) (Math.random()*256);//(Math.min(x,height-x)/ height * 2)*256;
                int G = 0;
                int B = 0;

               int val = (int)(R<<16) | (G<<8) | B;

                matrix += ""+val+"\t" ;

            }
            matrix +="\n";
        }

        try {
            //FileOutputStream fos = new FileOutputStream("Imagee.jpg");
            BufferedWriter fos = new BufferedWriter(new FileWriter("Imagee.jpg"));
            for (int x=0; x<=height; x++) {
                for ( int y=0; y<=width; y++) {
                fos.write(Integer.toHexString(Byte.toUnsignedInt(matrix.getBytes()[y]))+"\t");
                }fos.newLine();
            }
             fos.close();
            if(fos==null){System.out.println("Image has not been created correctly");}

        } catch(IOException error) {
            System.out.println("\nError!");
            error.getCause();
        }

    }

}

当我调试时，确实看到字符串中有值，我怀疑它们没有正确存储在文件中。任何帮助将不胜感激。