Java string set default value if null

Question

Is there a proficient way to set a string to some default value if assignment gives nullPointerException?

Say im initializing a string like this:

String myString= jsonElement.getAsJsonObject().get("myString").getAsString();

If it gives nullPointer i need to give it a default value, i know i can do it with an "if" check after but is that the only way? It would mean alot of checks as i am initiating around 20 strings.

Is there any way to do it like:

String myString = jsonElement.getAsJsonObject().get("myString")
    .getAsString() || "defaultValue";

"as i am initiating around 20 strings" ... when you what to get JSON data into variable, then you should use a proper JSON parser like Jackson or gson, instead of doing that yourself. — Tom
– Tom, Commented May 18, 2017 at 15:36
@steffen The return type of getAsJsonObject() is a JsonObject — A.Jac
– A.Jac, Commented May 18, 2017 at 16:13

korolar · Accepted Answer · 2017-05-18 15:36:52Z

5

You can use Optional for that, as in:

Optional.of(jsonElement).map(element -> element.getAsJsonObject()).map(o -> o.get("myString")).map(e -> e.getAsString()).orElse("defaultValue");

answered May 18, 2017 at 15:36

korolar

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1 Comment

Averroes Over a year ago

Put all the cases in an array. Loop over the array calling this with the elements of the array in the "myString" part.

matt · Accepted Answer · 2017-05-18 15:41:29Z

1

How about make a method to do that.

String getOrDefault(JsonElement jsonElement, String key)
    JsonObject obj = jsoneElement.getAsJsonObject().get(key);
    return obj==null?"default":obj.getAsString();
}

answered May 18, 2017 at 15:41

matt

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1 Comment

A.Jac Over a year ago

This looks like a good way to do it, and in my case i will have the same default value for all strings.

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