illegalargumentexception

I'm trying to write to an output file on my HTC One and get the following message in the LogCat: 11-21 08:05:18.228: W/System.err(6609): java.lang.IllegalArgumentException: File /storage/emulated/0/com.example.pattern1/myfile.txt contains a path separator The source code is given below: protected void writeToFile(String string){ File patternDirectory = new File(Environment.getExternalStorageDirectory().getAbsolutePath().toString()+"/com.example.pattern1/myfile.txt"); patternDirectory.mkdirs(); FileOutputStream outputStream; try { outputStream = openFileOutput(patternDirectory.getAbsolutePath()

I'm not sure if I'm having trouble with Reflection itself, or the method I'm trying to obtain. What I'd like to do is call the function setLine1Number from the class: com.android.internal.telephony.gsm.GSMPhone So that I can have my number properly inserted into my phone as it is not required to be in my SIM. Therefore I want to be able to call the function getLine1Number and have it return the same number that I set. Reflection appears the only way to be able to use this function as it is not in the public API. I've written this, but keep getting an illegal argument exception. Here is my code

When doing null checks in Java code, and you throw IllegalArgumentExceptions for null values, what kind of message template do you use? We tend to use something like this public User getUser(String username){ if (username == null){ throw new IllegalArgumentException("username is null"); } // ... } What is better : "is null" or "was null", and why? For me "is null" feels more natural. polygenelubricants Since the Exception is thrown due to a failed precondition check, I think rather than simply stating a fact, you should state the requirement that was violated. That is, instead of saying

This might look like a repeated question but I tried in all the below links and can't get a proper answer. Cannot format given Object as a Number ComboBox Illegal Argument Exception But I'm not getting whats wrong. Here is my code DecimalFormat twoDForm = new DecimalFormat("#.##"); double externalmark = 1.86; double internalmark = 4.0; System.out.println(String.valueOf((externalmark*3+internalmark*1)/4)); String val = String.valueOf((externalmark*3+internalmark*1)/4); String wgpa1=twoDForm.format(val); // gives exception String wgpa2=twoDForm.format((externalmark*3+internalmark*1)/4)); //