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0 pointsnitrogen14y ago0 comments

In 1997, before for-each and generics, it would've been very verbose. I learned Java in 2006 and haven't written much in a while, so I maybe slightly off, but I think you'd either get an Iterator for the Hashtable's keys and repeatedly call Iterator.next() and Hashtable.get(), or get the length of Hashtable.keys() and use a traditional C-style for loop.

Okay, I couldn't resist looking up the old docs, so this looks about right (Enumeration instead of Iterator -- two interfaces that do basically the same thing):

  void printTable(Hashtable table)
  {
    Enumeration e = table.keys();
    while(e.hasMoreElements()) {
      String key = (String)e.nextElement();
      String value = (String)table.get(key);
      System.out.println(key + ": " + value);
    }
  }

0 comments

arethuza14y ago

Yeah - that's pretty much it. Except that being lazy I'd have probably not bothered casting the keys and values to Strings and just called toString() on them directly....

onemoreact14y ago

Did you expect people to be able to do this by hand? I mean infront of an IDE I could do this in 5-10 minutes. But on a blackboard or pen and paper there is little chance I would get anywhere close to a correct answer.

kragen14y ago

I don't understand how that's possible. I mean, I'm going to assume that you're telling the truth, but I don't understand how it's possible for that knowledge to reside so entirely in your IDE rather than in your head. Do you mean you know that you would use an Enumeration, but not the names of the Enumeration and Hashtable methods that you would use? If you're trying to debug a piece of code and it's calling the wrong methods on an Enumeration or a Hashtable, how do you tell that they're the wrong methods? How does this work?

2 more replies

arethuza14y ago

This was the last question out of 15 or so that we used to give to people as part of an interview if they claimed they had done Java before - it was a written test. Some people had only done C or C++ before and had only had a quick look at Java and still did pretty well in it.

StavrosK14y ago

I see, thanks. It's more complicated than the Python version, which does the iteration implicitly, but I'm still surprised that nobody was able to do it.

phillytom14y ago

FYI - there's a potential defect there - keys are not required to be strings so you should lookup the value before you cast.

free14y ago

Ideally, whatever your key/value is would have the toString method over ridden to meaningfully represent it. Alternatively, I could write it as

for(Map.Entry<K, V> entry : map.entrySet()){

     System.out.println(entry.getKey());

     System.out.println(entry.getValue());

}

nitrogenOP14y ago

I was relying on the assumption from the original question that the keys and values were all Strings: "...a Hashtable containing String keys and values and printing them all out."

j / k navigate · click thread line to collapse

0 comments

arethuza14y ago

Yeah - that's pretty much it. Except that being lazy I'd have probably not bothered casting the keys and values to Strings and just called toString() on them directly....

onemoreact14y ago

kragen14y ago

2 more replies

arethuza14y ago

StavrosK14y ago

I see, thanks. It's more complicated than the Python version, which does the iteration implicitly, but I'm still surprised that nobody was able to do it.

phillytom14y ago

FYI - there's a potential defect there - keys are not required to be strings so you should lookup the value before you cast.

free14y ago

Ideally, whatever your key/value is would have the toString method over ridden to meaningfully represent it. Alternatively, I could write it as

for(Map.Entry<K, V> entry : map.entrySet()){

     System.out.println(entry.getKey());

     System.out.println(entry.getValue());

}

nitrogenOP14y ago

I was relying on the assumption from the original question that the keys and values were all Strings: "...a Hashtable containing String keys and values and printing them all out."

j / k navigate · click thread line to collapse