CODEWITHSUNDEEP
javastringnull
ono
ono

Reputation: 3102

Dealing with null-to-string errors

I have an object I'm retrieving and turning to a string. The .get() may return null, which in turn crashes when trying to convert to string. What the best way to deal with null in this case? Perhaps set it to an empty string if it returns null. I'm trying to avoid writing an if statement for each .get()

 String value1 = userDict.get("key1").toString();
 String value2 = userDict.get("key2").toString();
 String value3 = userDict.get("key3").toString();
 String value4 = userDict.get("key4").toString();

EDIT:

userDict is HashMap (String, Object)

Upvotes: 1

Views: 160

Answers (5)

Simon Curd
Simon Curd

Reputation: 850

I'd use a helper method. Something like this should work..

protected String getStringFromMap(Map<String,Object> map, String key)
{
   Object value = map.get(key);
   return value != null ? value.toString() : "";
}

Then you can call this as follows:

String value1 = getStringFromMap(userDict, "key1");
String value2 = getStringFromMap(userDict, "key2");
String value3 = getStringFromMap(userDict, "key3");
String value4 = getStringFromMap(userDict, "key4");

Upvotes: 0

Shrike
Shrike

Reputation: 155

Try using String.valueOf(userDict.get("key1")). According to the specs of valueOf(Object o), it will either call toString() on the object or return the string "null" if given a null Object.

EDIT: edited to point to the java 7 api instead of the java 6 api.

EDIT 2: If you don't mind making your code a bit more dense, you could encapsulate the logic of this method by using the ternary operator:

String value1 = (userDict.get("key1") == null) ? "" : userDict.get("key1").toString();

Upvotes: 5

stinepike
stinepike

Reputation: 54672

As Oli suggested you can create a helper get method like following

String helperGet(String key){
    YourClassType t = userDict.get("key1");
    if(t!=null)
       return t.toString();
    else
       return "";
}

Now call like following

 String value1 = userDict.helperGet("key1");
 String value2 = userDict.helperGet("key2");
 String value3 = userDict.helperGet("key3");
 String value4 = userDict.helperGet("key4");

Upvotes: 0

Chaos
Chaos

Reputation: 382

I would use a try-catch

  try {
    value1 = userDict.get("key1").toString();
  } catch (Exception e) {
    value1 = 0;
  }

Upvotes: -4

Oliver Charlesworth
Oliver Charlesworth

Reputation: 272467

Perhaps set it to an empty string if it returns null.

That's up to you. It depends what the purpose of this code is.

I'm trying to avoid writing an if statement for each .get()

If you want to avoid repetitive code, then write yourself a helper method.

Upvotes: 3

Related Questions