图像加载失败

Question

我正在使用Wp rest api将应用程序制作为Wordpress后端，但我遇到一个问题，首先尝试加载11张图像，当我全屏打开图像时，它可以正常工作到第9张图像，并滑动到第10张图像时显示错误加载失败，并且在下一张幻灯片应用程序停止了。。这是错误

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Integer packegename.model.wallpaper.Wallpaper.getId()' on a null object reference
    at packegename.activity.FullscreenActivity.setFabFavoriteIcon(FullscreenActivity.java:176)
    at packegename.activity.FullscreenActivity.updateInfo(FullscreenActivity.java:172)
    at packegename.activity.FullscreenActivity.access$100(FullscreenActivity.java:32)
    at com.mcc.wallpaper.activity.FullscreenActivity$1.onPageSelected(FullscreenActivity.java:118)
    at android.support.v4.view.ViewPager.dispatchOnPageSelected(ViewPager.java:1941)
    at android.support.v4.view.ViewPager.scrollToItem(ViewPager.java:680)
    at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:664)
    at android.support.v4.view.ViewPager.onTouchEvent(ViewPager.java:2257)
    at android.view.View.dispatchTouchEvent(View.java:10060)
    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2627)
    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2308)
    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2638)
    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2322)
    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2638)
    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2322)
    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2638)
    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2322)
    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2638)
    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2322)
    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2638)
    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2322)
    at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2638)
    at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2322)
    at com.android.internal.policy.DecorView.superDispatchTouchEvent(DecorView.java:414)
    at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1808)
    at android.app.Activity.dispatchTouchEvent(Activity.java:3108)
    at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:68)
    at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:68)
    at com.android.internal.policy.DecorView.dispatchTouchEvent(DecorView.java:376)
    at android.view.View.dispatchPointerEvent(View.java:10280)
    at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4449)
    at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4317)
    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3859)
    at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3917)
    at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3878)
    at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4010)
    at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3886)
    at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4067)
    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3859)
    at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3917)
    at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3878)
    at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3886)
    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3859)
    at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6262)
    at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6232)
    at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6193)
    at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:6365)
    at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:189)
    at android.os.MessageQueue.nativePollOnce(Native Method)

这是全屏活动

public class FullscreenActivity extends BaseActivity {

// variable
private Context mContext;
private Activity mActivity;
private WallpaperSliderAdapter sliderAdapter;
private ArrayList<Wallpaper> wallpapers;
private String wallpaperType;
private int currentPosition;

// constant
private static final int MY_PERMISSIONS_REQUEST_WRITE_STORAGE = 1001;

// ui elements
private ViewPager vpWallpaperSlider;
private TextView tvWallpaperCount;
private FloatingActionMenu fabMenu;
private FloatingActionButton fabShareWallpaper;
private FloatingActionButton fabFavoriteWallpaper;
private FloatingActionButton fabDownloadWallpaper;
private FloatingActionButton fabSetWallpaper;

private FavDbController favDbController;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // fullscreen
    this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

    initVariable();
    initView();
    initListener();
}

private void initVariable() {
    mContext = FullscreenActivity.this;
    mActivity = FullscreenActivity.this;

    if (getIntent().hasExtra(AppConstants.KEY_WALLPAPERS)) {
        wallpapers = getIntent().getParcelableArrayListExtra(AppConstants.KEY_WALLPAPERS);
    }

    if (getIntent().hasExtra(AppConstants.KEY_POSITION)) {
        currentPosition = getIntent().getIntExtra(AppConstants.KEY_POSITION, 0);
    }

    if (getIntent().hasExtra(AppConstants.KEY_WALLPAPER_TYPE)) {
        wallpaperType = getIntent().getStringExtra(AppConstants.KEY_WALLPAPER_TYPE);
    }

    sliderAdapter = new WallpaperSliderAdapter(getSupportFragmentManager(), wallpapers, wallpaperType);

    favDbController = new FavDbController(mContext);
}

private void initView() {
    setContentView(R.layout.activity_fullscreen);

    initToolbar();
    enableBackButton();

    vpWallpaperSlider = findViewById(R.id.vpWallpaperSlider);
    tvWallpaperCount = findViewById(R.id.tvWallpaperCount);
    fabMenu = findViewById(R.id.fabMenu);
    fabShareWallpaper = findViewById(R.id.fab_share_wallpaper);
    fabFavoriteWallpaper = findViewById(R.id.fab_favorite_wallpaper);
    fabDownloadWallpaper = findViewById(R.id.fab_download_wallpaper);
    fabSetWallpaper = findViewById(R.id.fab_set_wallpaper);

    vpWallpaperSlider.setAdapter(sliderAdapter);
    vpWallpaperSlider.setCurrentItem(currentPosition);

    updateInfo(currentPosition);
}

private void initListener() {
    vpWallpaperSlider.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {
            currentPosition = position;
            updateInfo(position);
        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }
    });

    fabShareWallpaper.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            shareWallpaper();
            fabMenu.close(true);
        }
    });

    fabFavoriteWallpaper.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            addTofavoriteWallpaper();
            setFabFavoriteIcon();
            fabMenu.close(true);
        }
    });

    fabDownloadWallpaper.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            if (ContextCompat.checkSelfPermission(mActivity,
                    Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {

                ActivityCompat.requestPermissions(mActivity,
                        new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                        MY_PERMISSIONS_REQUEST_WRITE_STORAGE);

            } else {
                saveWallpaper();
                fabMenu.close(true);
            }
        }
    });

    fabSetWallpaper.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            setWallpaper();
            fabMenu.close(true);
        }
    });
}

private void updateInfo(int position) {
    tvWallpaperCount.setText(StringUtil.addLeadingZero((position + 1)) + "/" + StringUtil.addLeadingZero(wallpapers.size()));
    setFabFavoriteIcon();
}

private void setFabFavoriteIcon() {
    if (favDbController.isFavorite(wallpapers.get(currentPosition).getId())) {
        fabFavoriteWallpaper.setImageResource(R.drawable.ic_favorite_orange_solid);
    } else {
        fabFavoriteWallpaper.setImageResource(R.drawable.ic_favorite_orange_border);
    }
}

private void shareWallpaper() {
    Fragment fragment = sliderAdapter.getFragment(vpWallpaperSlider.getCurrentItem());
    if (fragment != null) {
        if (wallpaperType.equals(AppConstants.TYPE_WALLPAPER)) {
            ((WallpaperSliderFragment) fragment).shareWallpaper();
        } else {
            ((GifSliderFragment) fragment).shareWallpaper();
        }
    }
}

private void addTofavoriteWallpaper() {
    Fragment fragment = sliderAdapter.getFragment(vpWallpaperSlider.getCurrentItem());
    if (fragment != null) {
        if (wallpaperType.equals(AppConstants.TYPE_WALLPAPER)) {
            ((WallpaperSliderFragment) fragment).addToFavoriteWallpaper();
        } else {
            ((GifSliderFragment) fragment).addToFavoriteWallpaper();
        }
    }
}

private void saveWallpaper() {
    Fragment fragment = sliderAdapter.getFragment(vpWallpaperSlider.getCurrentItem());
    if (fragment != null) {
        if (wallpaperType.equals(AppConstants.TYPE_WALLPAPER)) {
            ((WallpaperSliderFragment) fragment).saveWallpaper();
        } else {
            ((GifSliderFragment) fragment).saveWallpaper();
        }

    }
}

private void setWallpaper() {
    Fragment fragment = sliderAdapter.getFragment(vpWallpaperSlider.getCurrentItem());
    if (fragment != null) {
        if (wallpaperType.equals(AppConstants.TYPE_WALLPAPER)) {
            ((WallpaperSliderFragment) fragment).setWallpaper();
        } else {
            ((GifSliderFragment) fragment).setWallpaper();
        }
    }
}

@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case MY_PERMISSIONS_REQUEST_WRITE_STORAGE: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                saveWallpaper();

            } else {
                AlertDialog.Builder builder = new AlertDialog.Builder(mContext);
                builder.setMessage(getString(R.string.storage_permission_required_to_download));
                builder.setPositiveButton(getString(R.string.ok), new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        dialogInterface.dismiss();
                    }
                });

                AlertDialog dialog = builder.create();
                dialog.show();
            }
        }
    }
}

@Override
public void onBackPressed() {
    super.onBackPressed();
    this.finish();
}

@Override
public boolean onSupportNavigateUp() {
    onBackPressed();
    return super.onSupportNavigateUp();
}

}