我後來測試了一下有發現 bitmap 是 null

可是我確定路徑是正確的 /storage/emulated/0/cat.png

錯誤會出現在 canvas.drawBitmap(bitmap, 0, 0, paint);，

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.graphics.Bitmap.isRecycled()' on a null object

public class MyView extends View {
    public MyView(Context context) {
        super(context);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        // 獲取文件路徑
        String path = Environment.getExternalStorageDirectory()+"/cat.png";

        // 創建位圖對象
        Bitmap bitmap = BitmapFactory.decodeFile(path);

        Paint paint = new Paint();
        // 繪製圖片
        canvas.drawBitmap(bitmap, 0, 0, paint);
    }
}