Primitive type short - casting in Java

Question

I have a question about the primitive type short in Java  I am using JDK 1 6    If I have the following    short a   2  short b   3  short c   a   b    the compiler does not want to compile - it says that it  cannot convert from int to short  and suggests that I make a cast to short  so this   short c    short   a   b     really works  But my question is why do I need to cast  The values of a and b are in the range of short - the range of short values is  -32 768  32767   I also need to cast when I want to perform the operations -        I haven t checked for others    If I do the same for primitive type int  I do not need to cast aa bb to int  The following works fine   int aa   2  int bb   3  int cc   aa  bb    I discovered this while designing a class where I needed to add two variables of type short  and the compiler wanted me to make a cast  If I do this with two variables of type int  I don t need to cast    A small remark  the same thing also happens with the primitive type byte  So  this works   byte a   2  byte b   3  byte c    byte   a   b     but this not   byte a   2  byte b   3  byte c   a   b    For long  float  double  and int  there is no need to cast  Only for short and byte values

User · Answer

Given that the  why int by default  question hasn t been answered      First   default  is not really the right term  although close enough   As noted by VonC  an expression composed of ints and longs will have a long result  And an operation consisting of ints logs and doubles will have a double result  The compiler promotes the terms of an expression to whatever type provides a greater range and or precision in the result  floating point types are presumed to have greater range and precision than integral  although you do lose precision converting large longs to double    One caveat is that this promotion happens only for the terms that need it  So in the following example  the subexpression 5 4 uses only integral values and is performed using integer math  even though the overall expression involves a double  The result isn t what you might expect      5 4    1000 0   OK  so why are byte and short promoted to int  Without any references to back me up  it s due to practicality  there are a limited number of bytecodes     Bytecode   as its name implies  uses a single byte to specify an operation  For example iadd  which adds  two ints  Currently  205 opcodes are defined  and integer math takes 18 for each type  ie  36 total between integer and long   not counting conversion operators   If short  and byte each got their own set of opcodes  you d be at 241  limiting the ability of the JVM to expand  As I said  no references to back me up on this  but I suspect that Gosling et al said  how often do people actually use shorts   On the other hand  promoting byte to int leads to this not-so-wonderful effect  the expected answer is 96  the actual is -16    byte x    byte 0xC0  System out println x  gt  gt  2

User · Answer

In C  and Java  the arithmatic expression on the right hand side of the assignment evaluates to int by default  That s why you need to cast back to a short  because there is no implicit conversion form int to short  for obvious reasons

User · Answer

In java  every numeric expression like   anyPrimitive zas   1  anyPrimitive bar   3     x   zas    bar    x will always result to be at least an int  or a long if one of the addition elements was a long   But there s are some quirks tough  byte a   1     1 is an int  but it won t compile if you use a variable a    2     the shortcut works even when 2 is an int a       the post and pre increment operator work

User · Answer

I d like to add something that hasn t been pointed out  Java doesn t take into account the values you have given the variables  2 and 3  in     short a   2  short b   3  short c   a   b   So as far as Java knows  you could done this     short a   32767  short b   32767  short c   a   b   Which would be outside the range of short  it autoboxes the result to an int becuase it s  possible  that the result will be more than a short but not more than an int  Int was chosen as a  default  because basically most people wont be hard coding values above 2 147 483 647 or below -2 147 483 648

User · Answer

As explained in short C   but also for other language compilers as well  like Java   There is a predefined implicit conversion from short to int  long  float  double  or decimal   You cannot implicitly convert nonliteral numeric types of larger storage size to short  see Integral Types Table for the storage sizes of integral types   Consider  for example  the following two short variables x and y   short x   5  y   12    The following assignment statement will produce a compilation error  because the arithmetic expression on the right-hand side of the assignment operator evaluates to int by default   short z   x   y       Error  no conversion from int to short   To fix this problem  use a cast   short z    short  x   y        OK  explicit conversion   It is possible though to use the following statements  where the destination variable has the same storage size or a larger storage size   int m   x   y  long n   x   y      A good follow-up question is    why arithmetic expression on the right-hand side of the assignment operator evaluates to int by default     A first answer can be found in   Classifying and Formally Verifying Integer Constant Folding     The Java language specification defines exactly how integer numbers are represented and how integer arithmetic expressions are to be evaluated  This is an important property of Java as this programming language has been designed to be used in distributed applications on the Internet  A Java program is required to produce the same result independently of the target machine executing it        In contrast  C  and the majority of widely-used imperative and   object-oriented programming languages  is more sloppy and leaves many important characteristics open  The intention behind this inaccurate language   specification is clear  The same C programs are supposed to run on a 16-bit    32-bit  or even 64-bit architecture by instantiating the integer arithmetics of   the source programs with the arithmetic operations built-in in the target processor  This leads to much more e cient code because it can use the available   machine operations directly  As long as the integer computations deal only   with numbers being    sufficiently small     no inconsistencies will arise        In this sense  the C integer arithmetic is a placeholder which is not defined exactly   by the programming language specification but is only completely instantiated by determining the target machine        Java precisely defines how integers are represented and how integer arithmetic is to be computed           Java Integers -------------------------- Signed            Unsigned -------------------------- long   64-bit    int    32-bit    short  16-bit     char  16-bit  byte   8-bit          Char is the only unsigned integer type  Its values represent Unicode characters  from  u0000 to  uffff  i e  from 0 to 216-1        If an integer operator has an operand of type long  then the other operand is also converted to type long  Otherwise the operation is performed on operands of type int  if necessary shorter operands are converted into int  The conversion rules are exactly specified     From Electronic Notes in Theoretical Computer Science 82 No  2  2003  Blesner-Blech-COCV 2003  Sabine GLESNER  Jan Olaf BLECH  Fakult  t f  r Informatik  Universit  t Karlsruhe Karlsruhe  Germany

User · Answer

In C  and Java  the arithmatic expression on the right hand side of the assignment evaluates to int by default  That s why you need to cast back to a short  because there is no implicit conversion form int to short  for obvious reasons

User · Answer

What language are you using   Many C based languages have a rule that any mathematical expression is performed in size int or larger   Because of this  once you add two shorts the result is of type int   This causes the need for a cast

User · Answer

Any data type which is lower than  int   except Boolean  is implicitly converts to  int    In your case   short a   2  short b   3  short c   a   b    The result of  a b  is implicitly converted to an int  And now you are assigning it to  short  So that you are getting the error   short byte char --for all these we will get same error

User · Answer

I d like to add something that hasn t been pointed out  Java doesn t take into account the values you have given the variables  2 and 3  in     short a   2  short b   3  short c   a   b   So as far as Java knows  you could done this     short a   32767  short b   32767  short c   a   b   Which would be outside the range of short  it autoboxes the result to an int becuase it s  possible  that the result will be more than a short but not more than an int  Int was chosen as a  default  because basically most people wont be hard coding values above 2 147 483 647 or below -2 147 483 648

User · Answer

EDIT  Okay  now we know it s Java     Section 4 2 2 of the Java Language Specification states      The Java programming language provides   a number of operators that act on   integral values                  The numerical operators  which result   in a value of type int or long         The additive operators   and   -    15 18    In other words  it s like C  - the addition operator  when applied to integral types  only ever results in int or long  which is why you need to cast to assign to a short variable   Original answer  C    In C   you haven t specified the language  so I m guessing   the only addition operators on primitive types are   int operator   int x  int y   uint operator   uint x  uint y   long operator   long x  long y   ulong operator   ulong x  ulong y   float operator   float x  float y   double operator   double x  double y     These are in the C  3 0 spec  section 7 7 4  In addition  decimal addition is defined   decimal operator   decimal x  decimal y      Enumeration addition  string concatenation and delegate combination are also defined there    As you can see  there s no short operator   short x  short y  operator - so both operands are implicitly converted to int  and the int form is used  That means the result is an expression of type  int   hence the need to cast

User · Answer

I d like to add something that hasn t been pointed out  Java doesn t take into account the values you have given the variables  2 and 3  in     short a   2  short b   3  short c   a   b   So as far as Java knows  you could done this     short a   32767  short b   32767  short c   a   b   Which would be outside the range of short  it autoboxes the result to an int becuase it s  possible  that the result will be more than a short but not more than an int  Int was chosen as a  default  because basically most people wont be hard coding values above 2 147 483 647 or below -2 147 483 648

User · Answer

As explained in short C   but also for other language compilers as well  like Java   There is a predefined implicit conversion from short to int  long  float  double  or decimal   You cannot implicitly convert nonliteral numeric types of larger storage size to short  see Integral Types Table for the storage sizes of integral types   Consider  for example  the following two short variables x and y   short x   5  y   12    The following assignment statement will produce a compilation error  because the arithmetic expression on the right-hand side of the assignment operator evaluates to int by default   short z   x   y       Error  no conversion from int to short   To fix this problem  use a cast   short z    short  x   y        OK  explicit conversion   It is possible though to use the following statements  where the destination variable has the same storage size or a larger storage size   int m   x   y  long n   x   y      A good follow-up question is    why arithmetic expression on the right-hand side of the assignment operator evaluates to int by default     A first answer can be found in   Classifying and Formally Verifying Integer Constant Folding     The Java language specification defines exactly how integer numbers are represented and how integer arithmetic expressions are to be evaluated  This is an important property of Java as this programming language has been designed to be used in distributed applications on the Internet  A Java program is required to produce the same result independently of the target machine executing it        In contrast  C  and the majority of widely-used imperative and   object-oriented programming languages  is more sloppy and leaves many important characteristics open  The intention behind this inaccurate language   specification is clear  The same C programs are supposed to run on a 16-bit    32-bit  or even 64-bit architecture by instantiating the integer arithmetics of   the source programs with the arithmetic operations built-in in the target processor  This leads to much more e cient code because it can use the available   machine operations directly  As long as the integer computations deal only   with numbers being    sufficiently small     no inconsistencies will arise        In this sense  the C integer arithmetic is a placeholder which is not defined exactly   by the programming language specification but is only completely instantiated by determining the target machine        Java precisely defines how integers are represented and how integer arithmetic is to be computed           Java Integers -------------------------- Signed            Unsigned -------------------------- long   64-bit    int    32-bit    short  16-bit     char  16-bit  byte   8-bit          Char is the only unsigned integer type  Its values represent Unicode characters  from  u0000 to  uffff  i e  from 0 to 216-1        If an integer operator has an operand of type long  then the other operand is also converted to type long  Otherwise the operation is performed on operands of type int  if necessary shorter operands are converted into int  The conversion rules are exactly specified     From Electronic Notes in Theoretical Computer Science 82 No  2  2003  Blesner-Blech-COCV 2003  Sabine GLESNER  Jan Olaf BLECH  Fakult  t f  r Informatik  Universit  t Karlsruhe Karlsruhe  Germany

User · Answer

AFAIS  nobody mentions of final usage for that  If you modify your last example and define variables a and b as final variables  then the compiler is assured that their sum  value 5   can be assigned to a variable of type byte  without any loss of precision  In this case  the compiler is good to assign the sum of a and b to c   Here   s the modified code   final byte a   2  final byte b   3  byte c   a   b

User · Answer

What language are you using   Many C based languages have a rule that any mathematical expression is performed in size int or larger   Because of this  once you add two shorts the result is of type int   This causes the need for a cast

User · Answer

Java always uses at least 32 bit values for calculations  This is due to the 32-bit architecture which was common 1995 when java was introduced  The register size in the CPU was 32 bit and the arithmetic logic unit accepted 2 numbers of the length of a cpu register  So the cpus were optimized for such values   This is the reason why all datatypes which support arithmetic opperations and have less than 32-bits are converted to int  32 bit  as soon as you use them for calculations   So to sum up it mainly was due to performance issues and is kept nowadays for compatibility

User · Answer

In C  and Java  the arithmatic expression on the right hand side of the assignment evaluates to int by default  That s why you need to cast back to a short  because there is no implicit conversion form int to short  for obvious reasons

User · Answer

Any data type which is lower than  int   except Boolean  is implicitly converts to  int    In your case   short a   2  short b   3  short c   a   b    The result of  a b  is implicitly converted to an int  And now you are assigning it to  short  So that you are getting the error   short byte char --for all these we will get same error

User · Answer

I d like to add something that hasn t been pointed out  Java doesn t take into account the values you have given the variables  2 and 3  in     short a   2  short b   3  short c   a   b   So as far as Java knows  you could done this     short a   32767  short b   32767  short c   a   b   Which would be outside the range of short  it autoboxes the result to an int becuase it s  possible  that the result will be more than a short but not more than an int  Int was chosen as a  default  because basically most people wont be hard coding values above 2 147 483 647 or below -2 147 483 648

User · Answer

In C  and Java  the arithmatic expression on the right hand side of the assignment evaluates to int by default  That s why you need to cast back to a short  because there is no implicit conversion form int to short  for obvious reasons

User · Answer

AFAIS  nobody mentions of final usage for that  If you modify your last example and define variables a and b as final variables  then the compiler is assured that their sum  value 5   can be assigned to a variable of type byte  without any loss of precision  In this case  the compiler is good to assign the sum of a and b to c   Here   s the modified code   final byte a   2  final byte b   3  byte c   a   b

User · Answer

What language are you using   Many C based languages have a rule that any mathematical expression is performed in size int or larger   Because of this  once you add two shorts the result is of type int   This causes the need for a cast

User · Answer

As explained in short C   but also for other language compilers as well  like Java   There is a predefined implicit conversion from short to int  long  float  double  or decimal   You cannot implicitly convert nonliteral numeric types of larger storage size to short  see Integral Types Table for the storage sizes of integral types   Consider  for example  the following two short variables x and y   short x   5  y   12    The following assignment statement will produce a compilation error  because the arithmetic expression on the right-hand side of the assignment operator evaluates to int by default   short z   x   y       Error  no conversion from int to short   To fix this problem  use a cast   short z    short  x   y        OK  explicit conversion   It is possible though to use the following statements  where the destination variable has the same storage size or a larger storage size   int m   x   y  long n   x   y      A good follow-up question is    why arithmetic expression on the right-hand side of the assignment operator evaluates to int by default     A first answer can be found in   Classifying and Formally Verifying Integer Constant Folding     The Java language specification defines exactly how integer numbers are represented and how integer arithmetic expressions are to be evaluated  This is an important property of Java as this programming language has been designed to be used in distributed applications on the Internet  A Java program is required to produce the same result independently of the target machine executing it        In contrast  C  and the majority of widely-used imperative and   object-oriented programming languages  is more sloppy and leaves many important characteristics open  The intention behind this inaccurate language   specification is clear  The same C programs are supposed to run on a 16-bit    32-bit  or even 64-bit architecture by instantiating the integer arithmetics of   the source programs with the arithmetic operations built-in in the target processor  This leads to much more e cient code because it can use the available   machine operations directly  As long as the integer computations deal only   with numbers being    sufficiently small     no inconsistencies will arise        In this sense  the C integer arithmetic is a placeholder which is not defined exactly   by the programming language specification but is only completely instantiated by determining the target machine        Java precisely defines how integers are represented and how integer arithmetic is to be computed           Java Integers -------------------------- Signed            Unsigned -------------------------- long   64-bit    int    32-bit    short  16-bit     char  16-bit  byte   8-bit          Char is the only unsigned integer type  Its values represent Unicode characters  from  u0000 to  uffff  i e  from 0 to 216-1        If an integer operator has an operand of type long  then the other operand is also converted to type long  Otherwise the operation is performed on operands of type int  if necessary shorter operands are converted into int  The conversion rules are exactly specified     From Electronic Notes in Theoretical Computer Science 82 No  2  2003  Blesner-Blech-COCV 2003  Sabine GLESNER  Jan Olaf BLECH  Fakult  t f  r Informatik  Universit  t Karlsruhe Karlsruhe  Germany

User · Answer

As explained in short C   but also for other language compilers as well  like Java   There is a predefined implicit conversion from short to int  long  float  double  or decimal   You cannot implicitly convert nonliteral numeric types of larger storage size to short  see Integral Types Table for the storage sizes of integral types   Consider  for example  the following two short variables x and y   short x   5  y   12    The following assignment statement will produce a compilation error  because the arithmetic expression on the right-hand side of the assignment operator evaluates to int by default   short z   x   y       Error  no conversion from int to short   To fix this problem  use a cast   short z    short  x   y        OK  explicit conversion   It is possible though to use the following statements  where the destination variable has the same storage size or a larger storage size   int m   x   y  long n   x   y      A good follow-up question is    why arithmetic expression on the right-hand side of the assignment operator evaluates to int by default     A first answer can be found in   Classifying and Formally Verifying Integer Constant Folding     The Java language specification defines exactly how integer numbers are represented and how integer arithmetic expressions are to be evaluated  This is an important property of Java as this programming language has been designed to be used in distributed applications on the Internet  A Java program is required to produce the same result independently of the target machine executing it        In contrast  C  and the majority of widely-used imperative and   object-oriented programming languages  is more sloppy and leaves many important characteristics open  The intention behind this inaccurate language   specification is clear  The same C programs are supposed to run on a 16-bit    32-bit  or even 64-bit architecture by instantiating the integer arithmetics of   the source programs with the arithmetic operations built-in in the target processor  This leads to much more e cient code because it can use the available   machine operations directly  As long as the integer computations deal only   with numbers being    sufficiently small     no inconsistencies will arise        In this sense  the C integer arithmetic is a placeholder which is not defined exactly   by the programming language specification but is only completely instantiated by determining the target machine        Java precisely defines how integers are represented and how integer arithmetic is to be computed           Java Integers -------------------------- Signed            Unsigned -------------------------- long   64-bit    int    32-bit    short  16-bit     char  16-bit  byte   8-bit          Char is the only unsigned integer type  Its values represent Unicode characters  from  u0000 to  uffff  i e  from 0 to 216-1        If an integer operator has an operand of type long  then the other operand is also converted to type long  Otherwise the operation is performed on operands of type int  if necessary shorter operands are converted into int  The conversion rules are exactly specified     From Electronic Notes in Theoretical Computer Science 82 No  2  2003  Blesner-Blech-COCV 2003  Sabine GLESNER  Jan Olaf BLECH  Fakult  t f  r Informatik  Universit  t Karlsruhe Karlsruhe  Germany

User · Answer

Given that the  why int by default  question hasn t been answered      First   default  is not really the right term  although close enough   As noted by VonC  an expression composed of ints and longs will have a long result  And an operation consisting of ints logs and doubles will have a double result  The compiler promotes the terms of an expression to whatever type provides a greater range and or precision in the result  floating point types are presumed to have greater range and precision than integral  although you do lose precision converting large longs to double    One caveat is that this promotion happens only for the terms that need it  So in the following example  the subexpression 5 4 uses only integral values and is performed using integer math  even though the overall expression involves a double  The result isn t what you might expect      5 4    1000 0   OK  so why are byte and short promoted to int  Without any references to back me up  it s due to practicality  there are a limited number of bytecodes     Bytecode   as its name implies  uses a single byte to specify an operation  For example iadd  which adds  two ints  Currently  205 opcodes are defined  and integer math takes 18 for each type  ie  36 total between integer and long   not counting conversion operators   If short  and byte each got their own set of opcodes  you d be at 241  limiting the ability of the JVM to expand  As I said  no references to back me up on this  but I suspect that Gosling et al said  how often do people actually use shorts   On the other hand  promoting byte to int leads to this not-so-wonderful effect  the expected answer is 96  the actual is -16    byte x    byte 0xC0  System out println x  gt  gt  2

User · Answer

EDIT  Okay  now we know it s Java     Section 4 2 2 of the Java Language Specification states      The Java programming language provides   a number of operators that act on   integral values                  The numerical operators  which result   in a value of type int or long         The additive operators   and   -    15 18    In other words  it s like C  - the addition operator  when applied to integral types  only ever results in int or long  which is why you need to cast to assign to a short variable   Original answer  C    In C   you haven t specified the language  so I m guessing   the only addition operators on primitive types are   int operator   int x  int y   uint operator   uint x  uint y   long operator   long x  long y   ulong operator   ulong x  ulong y   float operator   float x  float y   double operator   double x  double y     These are in the C  3 0 spec  section 7 7 4  In addition  decimal addition is defined   decimal operator   decimal x  decimal y      Enumeration addition  string concatenation and delegate combination are also defined there    As you can see  there s no short operator   short x  short y  operator - so both operands are implicitly converted to int  and the int form is used  That means the result is an expression of type  int   hence the need to cast

User · Answer

In java  every numeric expression like   anyPrimitive zas   1  anyPrimitive bar   3     x   zas    bar    x will always result to be at least an int  or a long if one of the addition elements was a long   But there s are some quirks tough  byte a   1     1 is an int  but it won t compile if you use a variable a    2     the shortcut works even when 2 is an int a       the post and pre increment operator work

User · Answer

What language are you using   Many C based languages have a rule that any mathematical expression is performed in size int or larger   Because of this  once you add two shorts the result is of type int   This causes the need for a cast

User · Answer

EDIT  Okay  now we know it s Java     Section 4 2 2 of the Java Language Specification states      The Java programming language provides   a number of operators that act on   integral values                  The numerical operators  which result   in a value of type int or long         The additive operators   and   -    15 18    In other words  it s like C  - the addition operator  when applied to integral types  only ever results in int or long  which is why you need to cast to assign to a short variable   Original answer  C    In C   you haven t specified the language  so I m guessing   the only addition operators on primitive types are   int operator   int x  int y   uint operator   uint x  uint y   long operator   long x  long y   ulong operator   ulong x  ulong y   float operator   float x  float y   double operator   double x  double y     These are in the C  3 0 spec  section 7 7 4  In addition  decimal addition is defined   decimal operator   decimal x  decimal y      Enumeration addition  string concatenation and delegate combination are also defined there    As you can see  there s no short operator   short x  short y  operator - so both operands are implicitly converted to int  and the int form is used  That means the result is an expression of type  int   hence the need to cast

User · Answer

Java always uses at least 32 bit values for calculations  This is due to the 32-bit architecture which was common 1995 when java was introduced  The register size in the CPU was 32 bit and the arithmetic logic unit accepted 2 numbers of the length of a cpu register  So the cpus were optimized for such values   This is the reason why all datatypes which support arithmetic opperations and have less than 32-bits are converted to int  32 bit  as soon as you use them for calculations   So to sum up it mainly was due to performance issues and is kept nowadays for compatibility

User · Answer

Given that the  why int by default  question hasn t been answered      First   default  is not really the right term  although close enough   As noted by VonC  an expression composed of ints and longs will have a long result  And an operation consisting of ints logs and doubles will have a double result  The compiler promotes the terms of an expression to whatever type provides a greater range and or precision in the result  floating point types are presumed to have greater range and precision than integral  although you do lose precision converting large longs to double    One caveat is that this promotion happens only for the terms that need it  So in the following example  the subexpression 5 4 uses only integral values and is performed using integer math  even though the overall expression involves a double  The result isn t what you might expect      5 4    1000 0   OK  so why are byte and short promoted to int  Without any references to back me up  it s due to practicality  there are a limited number of bytecodes     Bytecode   as its name implies  uses a single byte to specify an operation  For example iadd  which adds  two ints  Currently  205 opcodes are defined  and integer math takes 18 for each type  ie  36 total between integer and long   not counting conversion operators   If short  and byte each got their own set of opcodes  you d be at 241  limiting the ability of the JVM to expand  As I said  no references to back me up on this  but I suspect that Gosling et al said  how often do people actually use shorts   On the other hand  promoting byte to int leads to this not-so-wonderful effect  the expected answer is 96  the actual is -16    byte x    byte 0xC0  System out println x  gt  gt  2

User · Answer

EDIT  Okay  now we know it s Java     Section 4 2 2 of the Java Language Specification states      The Java programming language provides   a number of operators that act on   integral values                  The numerical operators  which result   in a value of type int or long         The additive operators   and   -    15 18    In other words  it s like C  - the addition operator  when applied to integral types  only ever results in int or long  which is why you need to cast to assign to a short variable   Original answer  C    In C   you haven t specified the language  so I m guessing   the only addition operators on primitive types are   int operator   int x  int y   uint operator   uint x  uint y   long operator   long x  long y   ulong operator   ulong x  ulong y   float operator   float x  float y   double operator   double x  double y     These are in the C  3 0 spec  section 7 7 4  In addition  decimal addition is defined   decimal operator   decimal x  decimal y      Enumeration addition  string concatenation and delegate combination are also defined there    As you can see  there s no short operator   short x  short y  operator - so both operands are implicitly converted to int  and the int form is used  That means the result is an expression of type  int   hence the need to cast

User · Answer

Given that the  why int by default  question hasn t been answered      First   default  is not really the right term  although close enough   As noted by VonC  an expression composed of ints and longs will have a long result  And an operation consisting of ints logs and doubles will have a double result  The compiler promotes the terms of an expression to whatever type provides a greater range and or precision in the result  floating point types are presumed to have greater range and precision than integral  although you do lose precision converting large longs to double    One caveat is that this promotion happens only for the terms that need it  So in the following example  the subexpression 5 4 uses only integral values and is performed using integer math  even though the overall expression involves a double  The result isn t what you might expect      5 4    1000 0   OK  so why are byte and short promoted to int  Without any references to back me up  it s due to practicality  there are a limited number of bytecodes     Bytecode   as its name implies  uses a single byte to specify an operation  For example iadd  which adds  two ints  Currently  205 opcodes are defined  and integer math takes 18 for each type  ie  36 total between integer and long   not counting conversion operators   If short  and byte each got their own set of opcodes  you d be at 241  limiting the ability of the JVM to expand  As I said  no references to back me up on this  but I suspect that Gosling et al said  how often do people actually use shorts   On the other hand  promoting byte to int leads to this not-so-wonderful effect  the expected answer is 96  the actual is -16    byte x    byte 0xC0  System out println x  gt  gt  2

[java] Primitive type 'short' - casting in Java

Examples related to java

Examples related to casting

Examples related to primitive

Examples related to short