Databases
StackOverflow2013
Postsdbo
POJava.lang.NullPointerException when using retrieved Image (Unless method is used statically!)
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POJava.lang.NullPointerException when using retrieved Image (Unless method is used statically!)
    primarykey
    data
    text
    <p>In my MIDLet I have an instance of the java class ImageFetcher called anImg. Also within my MIDLet I have a command that simply say's fetch, a CommandListener that when detects fetch was clicked runs the function below. This function should simply run public getImage() from the anImg instance of class ImageFetcher which returns an image and then appends/sets this Image onto the form on the display. (You may recognise the getImage() function from the Nokia JavaME Wiki!!!)</p> <p>Instead of any image being displayed this is written to the output terminal in netbeans: Msg: Java.lang.NullPointerException</p> <p>HOWEVER, If I change public getImage() to public static getImage() and replace anImg.getImage() with ImageFetcher.getImage() the image is successfully displayed!!!</p> <p>Thank you for your replies on this issue :) I look forward to going my hair back after this ordeal!</p> <p>FetchImageApp.java</p> <pre><code>... ... public class FetchImageApp() extends MIDlet implements CommandListener { private ImageFetcher anImg; //this is my ImageFetcher instance, it is assigned within the constructor public FetchImageApp(){ anImg = new ImageFetcher(); //NO IT WASN'T, I knew it was something simple... I feel a fool... but I know we all do it! } ... private doThis(){ try { Image im; if ((im = anImg.getImage()) != null) { ImageItem ii = new ImageItem(null, im, ImageItem.LAYOUT_DEFAULT, null); // If there is already an image, set (replace) it if (form.size() != 0) { form.set(0, ii); } else // Append the image to the empty form { form.append(ii); } } else { form.append("Unsuccessful download."); } // Display the form with the image display.setCurrent(form); } catch (Exception e) { System.err.println("Msg: " + e.toString()); } } ... ... ... </code></pre> <p>ImageFetcher.java</p> <pre><code>... ... ... /*-------------------------------------------------- * Open connection and download png into a byte array. *-------------------------------------------------*/ public Image getImage() throws IOException { String url = "http://kenai.com/attachments/wiki_images/chessgame/java-duke-logo.png"; ContentConnection connection = (ContentConnection) Connector.open(url); // * There is a bug in MIDP 1.0.3 in which read() sometimes returns // an invalid length. To work around this, I have changed the // stream to DataInputStream and called readFully() instead of read() // InputStream iStrm = connection.openInputStream(); DataInputStream iStrm = connection.openDataInputStream(); ByteArrayOutputStream bStrm = null; Image im = null; try { // ContentConnection includes a length method byte imageData[]; int length = (int) connection.getLength(); if (length != -1) { imageData = new byte[length]; // Read the png into an array // iStrm.read(imageData); iStrm.readFully(imageData); } else // Length not available... { bStrm = new ByteArrayOutputStream(); int ch; while ((ch = iStrm.read()) != -1) { bStrm.write(ch); } imageData = bStrm.toByteArray(); bStrm.close(); } // Create the image from the byte array im = Image.createImage(imageData, 0, imageData.length); } finally { // Clean up if (iStrm != null) { iStrm.close(); } if (connection != null) { connection.close(); } if (bStrm != null) { bStrm.close(); } } return (im == null ? null : im); } ... ... ... </code></pre> <p>Here is the listener code as per request :)</p> <pre><code>public void commandAction(Command c, Displayable d) { if (c == doThisCommand) { if (c.getLabel().equals("Start")) { System.out.println("Started..."); begin(); //doThisCommand = new Command("Stop", Command.OK, 2); //ERROR:: After the command is changed to exit the program throws and unhandled excaption. } else { System.out.println("Stopped..."); doThisCommand = new Command("Start", Command.OK, 2); } } else if (c == exitCommand) { notifyDestroyed(); } else { throw new UnsupportedOperationException("Not supported yet."); } } </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USCœur
    1. USMatt Slaney
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POJava.lang.NullPointerException when using retrieved Image (Unless method is used statically!)
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload