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Methods must not throw RuntimeException, Exception, or Exception Throwable. Handling these exceptions requires catching RuntimeException, which is disallowed by rule ERR14ERR08-J. Do not catch NullPointerException or any of its ancestors. Moreover, throwing a RuntimeException can lead to subtle errors; for example, a caller cannot examine the exception to determine why it was thrown and consequently cannot attempt recovery.

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The isCapitalized() method in this noncompliant code example accepts a string and returns true when it the string consists of a capital letter followed by lowercase letters. The method also throws a RuntimeException when passed a null string argument.

boolean isCapitalized(String s) {
  if (s == null) {
    throw new RuntimeException("Null String");
  }
  if (s.equals("")) {
    return true;
  }
  String first = s.substring(0, 1);
  String rest = s.substring(1);
  return (first.equals(first.toUpperCase()) &&
          rest.equals(rest.toLowerCase()));
}

A calling method must also violate rule ERR14ERR08-J. Do not catch NullPointerException or any of its ancestors to determine if whether the RuntimeException was thrown.

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This compliant solution throws the (NullPointerException) to denote the specific exceptional condition.:

boolean isCapitalized(String s) {
  if (s == null) {
    throw new NullPointerException();
  }
  if (s.equals("")) {
    return true;
  }
  String first = s.substring(0, 1);
  String rest = s.substring(1);
  return (first.equals(first.toUpperCase()) &&
          rest.equals(rest.toLowerCase()));
}

Note that the null check is redundant; if it were removed, the next subsequent call (to s.equals("")) will would throw a NullPointerException when s is null. However, the explicit null check is a good form because it explicitly indicates the programmer's intent. More complex code may require explicit testing of invariants and appropriate throw statements.

Noncompliant Code Example

This noncompliant code example specifies the Exception class in the throws clause of the method declaration for the doSomething() method.:

private void doSomething() throws Exception {
  //...
}

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This compliant solution declares a more specific exception class in the throws clause of the method declaration for the doSomething() method.:

private void doSomething() throws IOException {
  //...
}

Exceptions

EXC07ERR07-J-EX0: Classes that sanitize exceptions to comply with a security policy are permitted to translate specific exceptions into more general exceptions. This translation could potentially result in throwing RuntimeException, Exception, or Exception Throwable in some cases, depending on the details requirements of the security policy.

Risk Assessment

Throwing RuntimeException and , Exception, or Throwable prevents classes from catching the intended exceptions without catching other unintended exceptions as well.

Automated Detection

Related Guidelines

Bibliography

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Image Added Image Added ERR06-J. Do not let code throw undeclared checked exceptions      06. Exceptional Behavior (ERR)