Page History

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This noncompliant code example attempts to delete a file but fails to check whether the operation has succeeded.

public void deleteFile(){

  File someFile = new File("someFileName.txt");
  // do something with someFile
  someFile.delete();

}

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This compliant solution checks the boolean value returned by the delete() method and handles any resulting errors.

public void deleteFile(){

  File someFile = new File("someFileName.txt");
  // do something with someFile
  if (!someFile.delete()) {
    // handle failure to delete the file
  }

}

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This noncompliant code example ignores the return value of the String.replace() method, failing to update the original string. The String.replace() method cannot modify the state of the String (because String objects are immutable); rather, it returns a reference to a new String object containing the modified string.

public class Replace {
  public static void main(String[] args) {
    String original = "insecure";
    original.replace('i', '9');
    System.out.println(original);
  }
}

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This compliant solution correctly updates the String reference original with the return value from the String.replace() method.

public class Replace {
  public static void main(String[] args) {
    String original = "insecure";
    original = original.replace('i', '9');
    System.out.println(original);
  }
}

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Automated Detection

Related Guidelines

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02. Expressions (EXP)      02. Expressions (EXP)      EXP01-J. Never dereference null pointers