Java not recognizing null value in jSonObject

Question

I have a jSonObject with key values pairs and i want to parse it to ContentValues. During the parse i want to detect wether the value is null, as you can see in the picture the value is null, but still it does not get catch by the if statement. Because it's a json and might be pasing null as string i tried to use value.equals("null") but neither it worked.

debug info

if ( value == null | value. equals("null") || tableField.getType() == FIELD_TYPE_NULL ) {
    DO SOME CODE
}

What's wrong ?

value == null | value. equals("null") if value is null not a null string won't value. equals("null") throw a NPE ? I think it should be written as "null".equals(value) — Nishant
– Nishant, Commented Dec 1, 2013 at 16:45
Did you print the value of value in console? Try System.out.println("Value:"+value+":"); and show me the exact output. — Ajeesh
– Ajeesh, Commented Dec 1, 2013 at 16:50
Yes, i did. System.out.println("value is "+value) prints value is null. when it should print value is, that's why i tried the value.equals("null") — spacebiker
– spacebiker, Commented Dec 1, 2013 at 16:55
Try to print the exact line what I have mentioned above and tell me the output — Ajeesh
– Ajeesh, Commented Dec 1, 2013 at 16:59
Then any one of these condition will be true value == null || value. equals("null"). But it didn't right? — Ajeesh
– Ajeesh, Commented Dec 1, 2013 at 17:06

Kyle Falconer · Accepted Answer · 2013-12-01 16:37:36Z

3

Your first "OR" is just a single pipe '|' instead of the double-pipe '||'

if ( value == null || value.equals("null") || tableField.getType() == FIELD_TYPE_NULL ) {
    DO SOME CODE
}

answered Dec 1, 2013 at 16:37

Kyle Falconer

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5 Comments

spacebiker Over a year ago

Yes, the OR operator in java can be single pipe or double pipe, if single, and the first statement is true it would not continue checking the next. This way i avoid nullpointer exception.

Kyle Falconer Over a year ago

@Xabier Sorry, that's close but not correct. the | is the bitwise OR operator, not the logical OR operator.

Tibor Blenessy Over a year ago

@Xabier see docs.oracle.com/javase/tutorial/java/nutsandbolts/… for reference.

tiguchi Over a year ago

Well, the Sun Java documentation states if both operands are boolean or Boolean then the result of bit-wise operators is boolean, too. That means that a single-pipe bit-wise OR turns into a boolean OR: docs.oracle.com/javase/specs/jls/se7/html/… ... it still doesn't make sense as OP intended. Using bit-wise OR should be as effective at avoiding NPE as boolean OR. Boolean expressions are evaluated from left to right. When you have an OR'ed two part-expression (A OR B) Java will evaluate the whole as true if A is already true.

spacebiker Over a year ago

@netinept I tried but same result. It does not stop. Somehow it is parsing the object null as string, inside the if, i do contentValues.put(columnName, ((value==null)? "": String.valueOf(value))) and it is filling the contentValue as string "null";

Ajeesh · Accepted Answer · 2013-12-01 17:27:27Z

1

The common way to retrieve values from jsonobject is using getString() method. So you must use value = jsonObject.getString(columnName); to assign the value for value variable. Then you need to check the condition as

if ( value == null || value. equals("null") || tableField.getType() == FIELD_TYPE_NULL ) 
{

}

answered Dec 1, 2013 at 17:27

Ajeesh

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1 Comment

spacebiker Over a year ago

That made it, what i do not understand yet is why it did not stop in one of both statements (value == null || value.equals("null"), get is supposed to return an object, so it should stop at least on value == null, still, if for some reason it was parsing as string it should stop in value.equals("null") . Anyway, this solution worked like a charm.

Neenem · Accepted Answer · 2013-12-01 16:43:10Z

1

Try using value.isNullObject() function. It returns true if the object is NULL.

answered Dec 1, 2013 at 16:43

Neenem

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1 Comment

spacebiker Over a year ago

value.isNullObject does not exist !?

M Sach · Accepted Answer · 2013-12-01 16:56:15Z

1

if ( value == null | value. equals("null") || tableField.getType() == FIELD_TYPE_NULL ) {
    DO SOME CODE
}

Though in your case if value is "null" above will turn out to be

value == null | value. equals("null")// first condition in if statement --->if(false|true)---> if(true)

you are using bit wise OR not logical OR

It should be

  if ( value == null || value. equals("null") || tableField.getType() == FIELD_TYPE_NULL ) {
        DO SOME CODE
    }

answered Dec 1, 2013 at 16:56

M Sach

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1 Comment

spacebiker Over a year ago

I tried that as suggested by @netinept but it didn't work. Thanks for your explanation.

score 1 · Accepted Answer · 2013-12-01 18:18:24Z

1

Try it

if ( value == null || value.equals("null") || tableField.getType() == FIELD_TYPE_NULL ) {
    DO SOME CODE
}

edited Dec 1, 2013 at 18:18

answered Dec 1, 2013 at 16:42

user2860053

1 Comment

spacebiker Over a year ago

StringUtils is not by default in android studio. I would prefer to avoid adding additional classes. At least just for checking if a value is null. But thanks anyway.

Samuel · Accepted Answer · 2013-12-01 16:38:35Z

0

You're missing one | in you first condition

answered Dec 1, 2013 at 16:38

Samuel

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1 Comment

spacebiker Over a year ago

Yes, the OR operator in java can be single pipe or double pipe, if single, and the first statement is true it would not continue checking the next. This way i avoid nullpointer exception.

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