storing a file

[Ivan Kesic]

Hello

I'm having a problem with storing a file (string) on phone. Its only 1 file with temperatures in it. But when i store a file, it just doesn't show up anywhere. Its never made. Tried some java tehnics with ObjectOutputStream but it doesn't work eider. What am i doing wrong?

  try {
			  EditText tempLocal = (EditText) findViewById(R.id.txtTemp);		  
			  temperature += tempLocal.getText()+";";
			  FileOutputStream fos = openFileOutput("temperature.txt", Context.MODE_PRIVATE);			  
			  fos.write(temperature.getBytes());
			  fos.close();	  
		} catch (Exception e) {
			e.printStackTrace();
		}

[Tim Moores]

What do you mean by "show up anywhere"? Are you using a file manager like OpenIntents?

Storing on the SD card works differently: http://developer.android.com/guide/topics/data/data-storage.html#filesExternal

[Ivan Kesic]

Hmmm, then here is a problem.

StringBuffer pom;
private void vratiTemperature() {
		try {
			FileInputStream fis = openFileInput("temperature.txt");
			int ch;
			
			while( (ch = fis.read()) != -1)
				pom.append((char)ch);

				fis.close(); 
				temperature = pom.toString();
				EditText tempLocal = (EditText) findViewById(R.id.txtSekunde);
				tempLocal.setText(temperature);
		} catch (Exception e) {
			e.printStackTrace();
		}

So, this opens the file and gets all of the text from it and puts it in tempLocal text field. But this method throws a nullpoint exception according to LogCat. Also this is all happening in Timer (Handler), and every time he refreshes, he makes a new temperature.txt file and stores it with old and new value. I can't figure out what is null here in this method.

[Tim Moores]

The stack trace should tell you that. Or you can post it here.

[Ivan Kesic]

11-04 19:47:35.103: WARN/System.err(277): java.lang.NullPointerException
11-04 19:47:35.122: WARN/System.err(277): at projekat.p1.ProjekatActivity.vratiTemperature(ProjekatActivity.java:113)
11-04 19:47:35.122: WARN/System.err(277): at projekat.p1.ProjekatActivity.access$0(ProjekatActivity.java:107)
11-04 19:47:35.122: WARN/System.err(277): at projekat.p1.ProjekatActivity$1.run(ProjekatActivity.java:73)
11-04 19:47:35.122: WARN/System.err(277): at android.os.Handler.handleCallback(Handler.java:587)
11-04 19:47:35.122: WARN/System.err(277): at android.os.Handler.dispatchMessage(Handler.java:92)
11-04 19:47:35.122: WARN/System.err(277): at android.os.Looper.loop(Looper.java:123)
11-04 19:47:35.122: WARN/System.err(277): at android.app.ActivityThread.main(ActivityThread.java:4627)
11-04 19:47:35.122: WARN/System.err(277): at java.lang.reflect.Method.invokeNative(Native Method)
11-04 19:47:35.131: WARN/System.err(277): at java.lang.reflect.Method.invoke(Method.java:521)
11-04 19:47:35.131: WARN/System.err(277): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
11-04 19:47:35.131: WARN/System.err(277): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
11-04 19:47:35.131: WARN/System.err(277): at dalvik.system.NativeStart.main(Native Method)

cant' realy figure out anything here...

[Tim Moores]

So which is line 113? What object is null?

[Ivan Kesic]

StringBuffer pom; line 113

so in method first it gets a number then, temperature = pom.toString(); It seems that here it throws a null, so pom doesn't append anything...

[Tim Moores]

So you should assign something to "pom" before you invoke methods on it.

[Ivan Kesic]

Im not sure i understand. I make StringBuffer pom as global variable. Then in method vratiTemperate() i do : pom.append((char)ch); In loop so i get all the text from file i open. Not sure what im doing wrong...

[Tim Moores]

So the relevant code is this:

    StringBuffer pom;
    pom.append((char)ch);

Can you now see what you're missing?

[Ivan Kesic]

So i needed to make = new StringBuffer(); So rookey mistake. I thought StringBuffer works like String... Thank you, now it works fine.