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try {
  //...
} catch (IOException ioe) { 
  // Ignore 
}

...

try {
  //...
} catch (IOException ioe) { 
  ioe.printStacktrace();
}

...

boolean volatile validFlag = false;
do {
  try {
    // If requested file does not exist, throws FileNotFoundException
    // If requested file exists, sets a Boolean flag validFlag to true
    validFlag = true; 
  } catch (FileNotFoundException e) { 
    // Ask the user for a different filename 
  }
} while(validFlag != true);
// Use the file

The user is allowed to access only files in a user-specific directory; consequently this approach avoids leaking . This prevents any other IOException that escapes the loop from leaking potentially sensitive file system information. See guideline EXC06-J. Do not allow exceptions to expose sensitive information for additional information.

Noncompliant Code Example

The If a thread is interrupted while sleeping or waiting, it causes a java.lang.InterruptedException to be thrown. But the run() method of a interface Runnable object cannot throw a checked exception. Consequently, this , and so it must handle InterruptedException. This noncompliant code example catches and suppresss java.lang.InterruptedException.

class Foo implements Runnable {
  public void run() {
    try {
      Thread.sleep(1000);    
    } catch (InterruptedException e) {
      // Ignore
    }
  }
}

This code prevents callers higher up the call stack from determining that an interrupted exception occurred; consequently, they are unable to act on the exception \[[Goetz 2006|AA. Bibliography#Goetz 06]\].  Likewise, if this code was called in its own thread, it prevents the calling thread from knowing that this thread was interrupted.

Compliant Solution

This compliant solution catches the InterruptedException and restores the interrupted status by calling the interrupt() method on the current thread.

class Foo implements Runnable {
  public void run() {
    try {
      Thread.sleep(1000);    
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt(); // Reset interrupted status
    }
  }
}

Consequently, code that is higher up on the call stack (or code from a calling thread) can see that an interrupt was issued \[[Goetz 2006|AA. Bibliography#Goetz 06]\].

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Some APIs may limit the permissible exceptions thrown by particular methods. In such cases, it may be necessary to catch an exception and either wrap it in a permitted exception or translate it to one of the permitted exceptions.

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try {
  // Requested file does not exist
  // User is unable to supply the file name
} catch (FileNotFoundException e) { 
  throw new RuntimeException(e);
}

*EXC00-EX3:* "The only situation in which it is acceptable to swallow an interrupt is when you are extending Thread and therefore control all the code higher up on the call stack" \[[Goetz 2006|AA. Bibliography#Goetz 06]\]. In such cases {{InterruptedException}} may be caught and suppressd. A interruption request may also be swallowedsuppressed by code that implements a thread's interruption policy \[[Goetz 2006, pg 143|AA. Bibliography#Goetz 06]\].

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