How do I convert from int to Long in Java

Question

I keep finding both on here and Google people having troubles going from long to int and not the other way around  Yet I m sure I m not the only one that has run into this scenario before going from int to Long   The only other answers I ve found were  Just set it as Long in the first place  which really doesn t address the question   I initially tried casting but I get a  Cannot cast from int to Long   for  int i   0  i  lt  myArrayList size      i         content   new Content        content setDescription myArrayList get i        content setSequence  Long  i       session save content       As you can imagine I m a little perplexed  I m stuck using int since some content is coming in as an ArrayList and the entity for which I m storing this info requires the sequence number as a Long

User · Answer

We shall get the long value by using Number reference   public static long toLong Number number       return number longValue        It works for all number types  here is a test   public static void testToLong   throws Exception       assertEquals 0l  toLong 0         an int     assertEquals 0l  toLong  short 0       a short     assertEquals 0l  toLong 0l       a long     assertEquals 0l  toLong  long  0       another long     assertEquals 0l  toLong 0 0f        a float     assertEquals 0l  toLong 0 0        a double

User · Answer

1 new Long intValue    2 Long valueOf intValue

User · Answer

As soon as there is only method Long valueOf long   cast from int to long will be done implicitly in case of using Long valueOf intValue    The more clear way to do this is  Integer valueOf intValue  longValue

User · Answer

If you already have the int typed as an Integer you can do this   Integer y   1  long x   y longValue

User · Answer

I have this little toy  that also deals with non generic interfaces  I m OK with it throwing a ClassCastException if feed wrong  OK and happy   public class TypeUtil       public static long castToLong Object o            Number n    Number  o          return n longValue

User · Answer

How About  int myInt   88       Will not compile  Long myLong   myInt       Compiles  and retains the non-NULL spirit of int  The best cast is no cast at all   Of course  your use case may require Long and possible NULL values   But if the int  or other longs are your only input  and your method can be modified  I would suggest this approach    long myLong   myInt       Compiles  is the most efficient way  and makes it clear that the source value  is and will never be NULL    Long myLong    long  myInt

User · Answer

use   new Long your integer     or  Long valueOf your integer

User · Answer

Suggested From Android Studio lint check   Remove Unnecessary boxing   So  unboxing is   public  static  long  integerToLong  int minute        int delay   minute 1000      long diff    long  delay      return  diff

User · Answer

I had a great deal of trouble with this  I just wanted to   thisBill IntervalCount   jPaidCountSpinner getValue      Where IntervalCount is a Long  and the JSpinner was set to return a Long   Eventually I had to write this function       public static final Long getLong Object obj  throws IllegalArgumentException       Long rv       if  obj getClass      Integer class      obj getClass      Long class      obj getClass      Double class             rv   Long parseLong obj toString               else if  obj getClass      int class      obj getClass      long class      obj getClass      double class             rv    Long  obj            else if obj getClass      String class            rv   Long parseLong obj toString               else           throw new IllegalArgumentException  getLong  type     obj getClass               obj toString         unaccounted for               return rv      which seems to do the trick   No amount of simple casting  none of the above solutions worked for me   Very frustrating

User · Answer

In Java you can do    int myInt 4   Long myLong  new Long myInt     in your case it would be    content setSequence new Long i

User · Answer

Note that there is a difference between a cast to long and a cast to Long  If you cast to long  a primitive value  then it should be automatically boxed to a Long  the reference type that wraps it    You could alternatively use new to create an instance of Long  initializing it with the int value

User · Answer

Suppose you have int and you wan to convert it to Long  int i 78     convert to Long  Long l Long valueOf i

User · Answer

Use the following  Long valueOf int

[java] How do I convert from int to Long in Java?

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