Or he could use a negative value to indicate "not found" — Glen. Matt Luongo Matt Luongo The OP already found that out himself as per the last phrase in his question: it was easy to figure out that it doesn't work.
For posterity nearly 4 years later- that bit was in a later edit. Jonathon Faust Jonathon Faust Along with all above answer i would like to add this point too. Shoaib Chikate Shoaib Chikate 7, 12 12 gold badges 43 43 silver badges 67 67 bronze badges. BalusC BalusC 1. Unfortunately if "check" returns an int rather than an Integer, this won't help, because the int which won't be null will be automatically boxed into the Integer. D'oh, that was just a basic example to show when you can test for null.
On the other hand, if check is declared to return int , it can never be null and the whole if block is then superfluous. Suraj Rao Minati Minati 51 1 1 silver badge 4 4 bronze badges. Nino van Hooff Nino van Hooff 3, 30 30 silver badges 48 48 bronze badges. No, but int[] can be. As Glen mentioned in a comment, you basically have two ways around this: use an "out of bound" value.
For instance, if "data" can never be negative in normal use, return a negative value to indicate it's invalid. Use an Integer. Just make sure the "check" method returns an Integer, and you assign it to an Integer not an int.
Because if an "int" gets involved along the way, the automatic boxing and unboxing can cause problems. Paul Tomblin Paul Tomblin k 56 56 gold badges silver badges bronze badges.
Sachin Pete Sachin Pete 7 4 4 bronze badges. Mohammad Fathi Mohammad Fathi 1 3 3 bronze badges. Since you ask for another way to accomplish your goal, I suggest you use a wrapper class: new Integer null ;. George 1 1 gold badge 8 8 silver badges 18 18 bronze badges. Sandy Sandy 1. How can i set null to integer variable initially instead of "0". I know already by default all int value is "0".
I used String. I dont want to print as "null". I want to print blank like " ". I get number format exception. Please give one solution for that. I am sure you are over-complicating the problem, it is a real simple thing to do.
Check the code below:. Use Integer wrapper class instead of primitive. Creating an instance of Integer with its primary value as null is meaningless, but you can do this on declaration:. The reason you're getting NumberFormatException is laid out in the documentation :. You can't call Integer. If you parse null or blank as int it will throw numberFormatException. Check for that before parsing:. My goal is to write a function which returns an int. I am doing this for homework but this specific part is not part of the homework, it just helps me get through what I am doing.
You need to be careful when unboxing null Integers since this can cause a lot of confusion and head scratching! To follow up on your question, if you want to indicate the absence of a value, I would investigate java. In Java, int is a primitive type and it is not considered an object.
Only objects can have a null value. The class Integer represents an int value, but it can hold a null value. Depending on your check method, you could be returning an int or an Integer. Only an fullworthy Object can be null , like Integer. Returns the number of one-bits in the two's complement binary representation of the specified int value. Returns the value of this Integer as a byte after a narrowing primitive conversion.
Compares two int values numerically treating the values as unsigned. Returns the unsigned quotient of dividing the first argument by the second where each argument and the result is interpreted as an unsigned value. Returns the value of this Integer as a double after a widening primitive conversion.
Returns the value of this Integer as a float after a widening primitive conversion. Returns a hash code for an int value; compatible with Integer. Returns an int value with at most a single one-bit, in the position of the highest-order "leftmost" one-bit in the specified int value. Returns the value of this Integer as a long after a widening primitive conversion. Returns an int value with at most a single one-bit, in the position of the lowest-order "rightmost" one-bit in the specified int value.
Returns the greater of two int values as if by calling Math. Returns the smaller of two int values as if by calling Math. Returns the number of zero bits preceding the highest-order "leftmost" one-bit in the two's complement binary representation of the specified int value. Returns the number of zero bits following the lowest-order "rightmost" one-bit in the two's complement binary representation of the specified int value. Parses the CharSequence argument as a signed int in the specified radix , beginning at the specified beginIndex and extending to endIndex - 1.
Parses the string argument as a signed integer in the radix specified by the second argument. Parses the CharSequence argument as an unsigned int in the specified radix , beginning at the specified beginIndex and extending to endIndex - 1. Parses the string argument as an unsigned integer in the radix specified by the second argument.
Returns the unsigned remainder from dividing the first argument by the second where each argument and the result is interpreted as an unsigned value. Returns the value obtained by reversing the order of the bits in the two's complement binary representation of the specified int value. Returns the value obtained by reversing the order of the bytes in the two's complement representation of the specified int value.
Returns the value obtained by rotating the two's complement binary representation of the specified int value left by the specified number of bits. Returns the value obtained by rotating the two's complement binary representation of the specified int value right by the specified number of bits.
Returns the value of this Integer as a short after a narrowing primitive conversion. Returns a string representation of the integer argument as an unsigned integer in base 2. Returns a string representation of the integer argument as an unsigned integer in base Returns a string representation of the integer argument as an unsigned integer in base 8. Returns a String object representing this Integer 's value. Returns a string representation of the first argument in the radix specified by the second argument.
Returns a string representation of the first argument as an unsigned integer value in the radix specified by the second argument. Returns an Integer instance representing the specified int value.
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