Testing for null JSON Objects in Java/Android
Solution 1
Use the following method of JsonObject
to check if a value against any key is null
public boolean isNull(java.lang.String key)
This method is used to check Null against any key or if there is no value for the key.
Use below snippet
if (jsonObject.isNull("AverageRating")) {
Toast.makeText(this, "Cannot Convert!!", Toast.LENGTH_LONG).show();
//float set to 0
} else {
Float.valueOf(jsonObject.getString("AverageRating"));
}
Solution 2
String str = jObject.getString("AverageRating");
float number = 0.f;
try
{
number = Float.parseFloat(str);
}
catch (NumberFormatException e)
{
number = 0;
}
parseFloat()
will throw an exception if it receives null
.
TheLettuceMaster
Android (Java) Developer for fun, and Professional Full Stack Developer using python, ruby, JavaScript, SQL and php.
Updated on June 16, 2022Comments
-
TheLettuceMaster almost 2 years
I am getting this LogCat:
06-22 15:30:53.731: E/AndroidRuntime(2389): java.lang.NumberFormatException: Invalid float: "null" 06-22 15:30:53.731: E/AndroidRuntime(2389): at java.lang.StringToReal.invalidReal(StringToReal.java:63) 06-22 15:30:53.731: E/AndroidRuntime(2389): at java.lang.StringToReal.parseFloat(StringToReal.java:310) 06-22 15:30:53.731: E/AndroidRuntime(2389): at java.lang.Float.parseFloat(Float.java:300) 06-22 15:30:53.731: E/AndroidRuntime(2389): at java.lang.Float.valueOf(Float.java:337)
Here is code:
try { jObject = new JSONObject(result); starAvg = jObject.getString("AverageRating"); } ratingsBar = (RatingBar) findViewById(R.id.theRatingBar); ratingsBar.setRating(Float.valueOf(starAvg));
Here is the context:
In PHP, I am averaging total numbers in a column in a MySQL table. When there are ANY rows, it will send back an average of the data in it and it encodes it, and Java picks it up as a JSON object. But sometimes, there are cases where a table may have 0 rows, so I get this JSON Object:
{"AverageRating":null}
My app then crashes and the
LogCat
is as seen above.The
String
doesn't seem to care if it picks up a Null JSON Object but the app crashes when I doFloat.valueOf(theString)
.Another side note, I have tried to test this way:
if String is Null, Float = 0 if String is not null, Float.valueOF(String)
But it doesn't ever seem to read the String as null. Is it actually NOT
null
in this case?