java - ImageView.setImageBitmap 始终为 null

Question

我正在尝试从 interwebz 加载图像，但出现空指针异常。这是我的代码:

public class Search extends ActionBarActivity {
TableLayout tableScrollView;
String[] JSONExceptions = { "type", "em", "user_id", "id", "profilepic",
        "bg" };
String value;
JSONObject jObject;

private float mx, my;
private float curX, curY;

private ScrollView vScroll;
private HorizontalScrollView hScroll;
private Bitmap profilepic;
private ImageView iv;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_search);

    vScroll = (ScrollView) findViewById(R.id.vScroll);
    hScroll = (HorizontalScrollView) findViewById(R.id.hScroll);
    iv = (ImageView) findViewById(R.id.imageView);
    Bundle extras = getIntent().getExtras();
    if (extras != null) {
        value = extras.getString("id");
    }
    System.out.println(value);
    tableScrollView = (TableLayout) findViewById(R.id.tableScrollView);
    Thread thread = new Thread(new Runnable() {
        @Override
        public void run() {
            jObject = getJson("http://www.tabcards.com/req/androidapi/L2o30H8JlFMtFYHW3KLxkts20ztc5Be6Z6m6v315/json/"
                    + value);
            try {
                profilepic = BitmapFactory.decodeStream(new URL(jObject.getString("profilepic")).openConnection().getInputStream());
                iv.setImageBitmap(profilepic);
            } catch (MalformedURLException e1) {
                e1.printStackTrace();
            } catch (IOException e1) {
                e1.printStackTrace();
            } catch (Exception e1) {
                e1.printStackTrace();
            }
            runOnUiThread(new Runnable() {

                @Override
                public void run() {
                    try {

                        System.out.println("awaking");
                        createUI(jObject);
                        System.out.println("done");

                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }

            });

        }
    });
    thread.start();

    System.out.println("complete");

}

private void createUI(JSONObject jObject) throws JSONException {
    int absIndex = 0;
    String value = jObject.getString("name");
    if (value != "" && !jObject.getString("profilepic").equals("")) {
        System.out.println(jObject.getString("profilepic"));

            insertElement(value, absIndex++, true);
    }


}



public static Bitmap drawableToBitmap (Drawable drawable) {
    Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap); 
    drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
    drawable.draw(canvas);

    return bitmap;
}

public static Bitmap getclip(Bitmap bitmap) {
    Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
            bitmap.getHeight(), Config.ARGB_8888);
    Canvas canvas = new Canvas(output);

    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());

    paint.setAntiAlias(true);
    canvas.drawARGB(0, 0, 0, 0);
    canvas.drawCircle(bitmap.getWidth() / 2, bitmap.getHeight() / 2,
            bitmap.getWidth() / 2, paint);
    paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
    canvas.drawBitmap(bitmap, rect, rect, paint);
    return output;
}


public Bitmap getCroppedBitmap(Bitmap bitmap) {
    Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
            bitmap.getHeight(), Config.ARGB_8888);
    Canvas canvas = new Canvas(output);

    final int color = 0xff424242;
    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());

    paint.setAntiAlias(true);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(color);
    // canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
    canvas.drawCircle(bitmap.getWidth() / 2, bitmap.getHeight() / 2,
            bitmap.getWidth() / 2, paint);
    paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
    canvas.drawBitmap(bitmap, rect, rect, paint);
    //Bitmap _bmp = Bitmap.createScaledBitmap(output, 60, 60, false);
    //return _bmp;
    return output;
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.search, menu);
    return true;
}



private void insertElement(String data, int i, boolean flag) {
    LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View newRow = inflater.inflate(R.layout.row, null, false);
    newRow.setLayoutParams(new TableRow.LayoutParams(
            TableRow.LayoutParams.MATCH_PARENT,
            TableRow.LayoutParams.WRAP_CONTENT));

    TextView dataTextView = (TextView) newRow
            .findViewById(R.id.rowTextView);
    dataTextView.setText(data);

    if(!flag) {
        iv.setVisibility(View.GONE);
    }
    System.out.println(dataTextView.getText().toString());
    tableScrollView.addView(newRow, i);     
}

public static boolean useLoop(String[] arr, String targetValue) {
    for(String s: arr){
        if(s.equals(targetValue))
            return true;
    }
    return false;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

public static <T> boolean contains2(final T[] array, final T v) {
    if (v == null) {
        for (final T e : array)
            if (e == null)
                return true;
    } else {
        for (final T e : array)
            if (e == v || v.equals(e))
                return true;
    }

    return false;
}

public static Drawable LoadImageFromWeb(String url) {
    try {
        InputStream is = (InputStream) new URL(url).getContent();
        Drawable d = Drawable.createFromStream(is, "src name");
        return d;
    } catch (Exception e) {
        return null;
    }
}

// Given a string representation of a URL, sets up a connection and gets
// an input stream.
private InputStream downloadUrl(String urlString) throws IOException {
    URL url = new URL(urlString);
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setReadTimeout(10000 /* milliseconds */);
    conn.setConnectTimeout(15000 /* milliseconds */);
    conn.setRequestMethod("GET");
    conn.setDoInput(true);
    // Starts the query
    conn.connect();
    return conn.getInputStream();
}

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

public static JSONObject getJson(String url) {

    InputStream is = null;
    String result = "";
    JSONObject jsonObject = null;

    // HTTP
    try {
        HttpClient httpclient = new DefaultHttpClient(); // for port 80
                                                            // requests!
        HttpPost httppost = new HttpPost(url);
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity entity = response.getEntity();
        is = entity.getContent();
    } catch (Exception e) {
        return null;
    }

    // Read response to string
    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                is, "utf-8"), 8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
            System.out.println(line);
        }
        is.close();
        result = sb.toString().replace("[", "");
        System.out.println("done getting obj : " + result);

    } catch (Exception e) {
        return null;
    }

    // Convert string to object
    try {
        jsonObject = new JSONObject(result.replace("]", ""));
    } catch (JSONException e) {
        return null;
    }

    return jsonObject;

}

@Override
public boolean onTouchEvent(MotionEvent event) {
    float curX, curY;

    switch (event.getAction()) {

        case MotionEvent.ACTION_DOWN:
            mx = event.getX();
            my = event.getY();
            break;
        case MotionEvent.ACTION_MOVE:
            curX = event.getX();
            curY = event.getY();
            vScroll.scrollBy((int) (mx - curX), (int) (my - curY));
            hScroll.scrollBy((int) (mx - curX), (int) (my - curY));
            mx = curX;
            my = curY;
            break;
        case MotionEvent.ACTION_UP:
            curX = event.getX();
            curY = event.getY();
            vScroll.scrollBy((int) (mx - curX), (int) (my - curY));
            hScroll.scrollBy((int) (mx - curX), (int) (my - curY));
            break;
    }

    return true;
}
}

它主要在我处理它的线程中。我不知道发生了什么事，我尝试查看其他问题，但没有一个解决我的问题。我检索到的图像没问题，我的意思是，我执行了 profilepic.getWidth() 并且它返回了实际的准确值。

Answer 1

问题是您的 imageview 不存在于您在 Activity 中使用的 xml 中，因此给您带来了 NPE。您不能使用 Activity 布局中不存在的 View

解决方案

在 Activity_search.xml 中添加 xml，并确保在 runonuithread 中设置 imagebackground。