Question

在我的代码中，我使用AQUery库从web加载图像，但它在“aq.id（R.id.img）;”处显示空指针异常。在我的代码中...在类中我创建了AQuery类的全局对象，我在内部类methode中定义了函数.....在“aq.id（R.id.img）”中的空指针异常，这是在getview方法中的cusomgrid类..

public class Customgrid extends Activity {

public int gotbread;
public int get, send;
AQuery aq;
String url1[] = { "https://www.dropbox.com/s/f308a9s5ycuc3mh/1.jpg",
        "https://dl.dropbox.com/s/2s60g4e696566nt/2.jpg",
        "https://dl.dropbox.com/s/59t6wo83ekzff0y/3.jpg",
        "https://dl.dropbox.com/s/1b58qtj4ftm87yc/4.jpg",
        "https://dl.dropbox.com/s/py7ogwstc0814zg/5.jpg",
        "https://dl.dropbox.com/s/ocavtv1tkr6wtvv/6.jpg" };

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.customgview);
    AQuery aq = new AQuery(Customgrid.this);

    // Bundle gotbasket = getIntent().getExtras();
    // gotbread = gotbasket.getInt("pos");
    gotbread = getIntent().getExtras().getInt("position");
    get = gotbread;
    GridView grdview = (GridView) findViewById(R.id.gridView);
    grdview.setAdapter(new Customgridadapter(this));
    grdview.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1,
                int position, long arg3) {
            // TODO Auto-generated method stub

            Bundle basket = new Bundle();
            basket.putInt("position", send);
            Intent i = new Intent(Customgrid.this,
                    FullScreenImageActivity.class);
            i.putExtras(basket);
            startActivity(i);
        }
    });
    grdview.setVerticalSpacing(0);

}

private InputStream OpenHttpConnection(String urlString) throws IOException {
    InputStream in = null;
    int response = -1;

    URL url = new URL(urlString);
    URLConnection conn = url.openConnection();

    if (!(conn instanceof HttpURLConnection))
        throw new IOException("Not an HTTP connection");

    try {
        HttpURLConnection httpConn = (HttpURLConnection) conn;
        httpConn.setAllowUserInteraction(false);
        httpConn.setInstanceFollowRedirects(true);
        httpConn.setRequestMethod("GET");
        httpConn.connect();

        response = httpConn.getResponseCode();
        if (response == HttpURLConnection.HTTP_OK) {
            in = httpConn.getInputStream();
        }
    } catch (Exception ex) {
        throw new IOException("Error connecting");
    }
    return in;
}

private Bitmap DownloadImage(String URL) {
    Bitmap bitmap = null;
    InputStream in = null;
    try {
        in = OpenHttpConnection(URL);
        bitmap = BitmapFactory.decodeStream(in);
        in.close();
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }
    return bitmap;
}

public class Customgridadapter extends BaseAdapter {
    public Integer[] images1 = { R.drawable.s_1, R.drawable.s_2,
            R.drawable.s_3 };
    public Integer[] images2 = { R.drawable.s_5, R.drawable.s_6,
            R.drawable.s_4 };
    Context m1Context;

    public Customgridadapter(Context context) {
        super();
        this.m1Context = context;
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return images1.length;
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return 0;
    }

    @SuppressLint("NewApi")
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        int pos = 0;
        LayoutInflater inflater = ((Activity) m1Context)
                .getLayoutInflater();
        View customRow1 = inflater.inflate(R.layout.gview, null);
        ImageView image = (ImageView) customRow1
                .findViewById(R.id.imageforgrid);
        aq.id(R.id.imageforgrid);
        aq.image(url1[0],true,true);

        Bitmap bm = DownloadImage(url1[0]);
        switch (gotbread) {
        case 0:

            image.setImageBitmap(bm);
            break;
        case 1:
            image.setImageBitmap(bm);

            break;
        }
        image.setAdjustViewBounds(true);
        image.setScaleX((float) 0.9);
        image.setScaleY((float) 0.9);
        switch (get) {
        case 0:
            send = get + position;
            break;
        case 1:
            send = 10 * 1 + position;
            break;
        case 2:
            send = 10 * 2 + position;
            break;
        case 3:
            send = 10 * 3 + position;
            break;
        case 4:
            send = 10 * 4 + position;
            break;

        }

        // image.setOnClickListener(new OnImageClickListener(position));
        return customRow1;
    }
}

Answer 1

你有

  AQuery aq = new AQuery(Customgrid.this); // declared and initialized in oncreate

onCreate中的

变为onCreate的本地。

更改为

  aq = new AQuery(Customgrid.this);

实例变量aq从未初始化给出NPE。

public class Customgrid extends Activity {

public int gotbread;
public int get, send;
AQuery aq; // not initialized

ui线程上也没有与网络相关的操作。

AQuery（Android查询）函数中的空指针异常

1 个答案: