What is the size of a boolean variable in Java

Question

Can any one tell the bit size of boolean in Java

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It s undefined  doing things like Jon Skeet suggested will get you an approximation on a given platform  but the way to know precisely for a specific platform is to use a profiler

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It depends on the virtual machine  but it s easy to adapt the code from a similar question asking about bytes in Java   class LotsOfBooleans       boolean a0  a1  a2  a3  a4  a5  a6  a7  a8  a9  aa  ab  ac  ad  ae  af      boolean b0  b1  b2  b3  b4  b5  b6  b7  b8  b9  ba  bb  bc  bd  be  bf      boolean c0  c1  c2  c3  c4  c5  c6  c7  c8  c9  ca  cb  cc  cd  ce  cf      boolean d0  d1  d2  d3  d4  d5  d6  d7  d8  d9  da  db  dc  dd  de  df      boolean e0  e1  e2  e3  e4  e5  e6  e7  e8  e9  ea  eb  ec  ed  ee  ef     class LotsOfInts       int a0  a1  a2  a3  a4  a5  a6  a7  a8  a9  aa  ab  ac  ad  ae  af      int b0  b1  b2  b3  b4  b5  b6  b7  b8  b9  ba  bb  bc  bd  be  bf      int c0  c1  c2  c3  c4  c5  c6  c7  c8  c9  ca  cb  cc  cd  ce  cf      int d0  d1  d2  d3  d4  d5  d6  d7  d8  d9  da  db  dc  dd  de  df      int e0  e1  e2  e3  e4  e5  e6  e7  e8  e9  ea  eb  ec  ed  ee  ef      public class Test       private static final int SIZE   1000000       public static void main String   args  throws Exception                       LotsOfBooleans   first   new LotsOfBooleans SIZE           LotsOfInts   second   new LotsOfInts SIZE            System gc            long startMem   getMemory             for  int i 0  i  lt  SIZE  i                          first i    new LotsOfBooleans                       System gc            long endMem   getMemory             System out println   Size for LotsOfBooleans       endMem-startMem            System out println   Average size        endMem-startMem      double SIZE              System gc            startMem   getMemory            for  int i 0  i  lt  SIZE  i                          second i    new LotsOfInts                      System gc            endMem   getMemory             System out println   Size for LotsOfInts       endMem-startMem            System out println   Average size        endMem-startMem      double SIZE                 Make sure nothing gets collected         long total   0          for  int i 0  i  lt  SIZE  i                          total     first i  a0   1   0    second i  a0                    System out println total              private static long getMemory                 Runtime runtime   Runtime getRuntime            return runtime totalMemory   - runtime freeMemory              To reiterate  this is VM-dependent  but on my Windows laptop running Sun s JDK build 1 6 0 11 I got the following results   Size for LotsOfBooleans  87978576 Average size  87 978576 Size for LotsOfInts  328000000 Average size  328 0   That suggests that booleans can basically be packed into a byte each by Sun s JVM

User · Answer

It s virtual machine dependent

User · Answer

It s virtual machine dependent

User · Answer

The boolean values are compiled to int data type in JVM  See here

User · Answer

It s undefined  doing things like Jon Skeet suggested will get you an approximation on a given platform  but the way to know precisely for a specific platform is to use a profiler

User · Answer

Size of the boolean in java is virtual machine dependent  but Any Java object is aligned to an 8 bytes granularity  A Boolean has 8 bytes of header  plus 1 byte of payload  for a total of 9 bytes of information  The JVM then rounds it up to the next multiple of 8  so the one instance of java lang Boolean takes up 16 bytes of memory

User · Answer

The actual information represented by a boolean value in Java is one bit  1 for true  0 for false  However  the actual size of a boolean variable in memory is not precisely defined by the Java specification  See Primitive Data Types in Java      The boolean data type has only two   possible values  true and false  Use   this data type for simple flags that   track true false conditions  This data   type represents one bit of   information  but its  size  isn t   something that s precisely defined

User · Answer

On a side note     If you are thinking about using an array of Boolean objects  don t   Use a BitSet instead - it has some performance optimisations  and some nice extra methods  allowing you to get the next set unset bit

User · Answer

It depends on the virtual machine  but it s easy to adapt the code from a similar question asking about bytes in Java   class LotsOfBooleans       boolean a0  a1  a2  a3  a4  a5  a6  a7  a8  a9  aa  ab  ac  ad  ae  af      boolean b0  b1  b2  b3  b4  b5  b6  b7  b8  b9  ba  bb  bc  bd  be  bf      boolean c0  c1  c2  c3  c4  c5  c6  c7  c8  c9  ca  cb  cc  cd  ce  cf      boolean d0  d1  d2  d3  d4  d5  d6  d7  d8  d9  da  db  dc  dd  de  df      boolean e0  e1  e2  e3  e4  e5  e6  e7  e8  e9  ea  eb  ec  ed  ee  ef     class LotsOfInts       int a0  a1  a2  a3  a4  a5  a6  a7  a8  a9  aa  ab  ac  ad  ae  af      int b0  b1  b2  b3  b4  b5  b6  b7  b8  b9  ba  bb  bc  bd  be  bf      int c0  c1  c2  c3  c4  c5  c6  c7  c8  c9  ca  cb  cc  cd  ce  cf      int d0  d1  d2  d3  d4  d5  d6  d7  d8  d9  da  db  dc  dd  de  df      int e0  e1  e2  e3  e4  e5  e6  e7  e8  e9  ea  eb  ec  ed  ee  ef      public class Test       private static final int SIZE   1000000       public static void main String   args  throws Exception                       LotsOfBooleans   first   new LotsOfBooleans SIZE           LotsOfInts   second   new LotsOfInts SIZE            System gc            long startMem   getMemory             for  int i 0  i  lt  SIZE  i                          first i    new LotsOfBooleans                       System gc            long endMem   getMemory             System out println   Size for LotsOfBooleans       endMem-startMem            System out println   Average size        endMem-startMem      double SIZE              System gc            startMem   getMemory            for  int i 0  i  lt  SIZE  i                          second i    new LotsOfInts                      System gc            endMem   getMemory             System out println   Size for LotsOfInts       endMem-startMem            System out println   Average size        endMem-startMem      double SIZE                 Make sure nothing gets collected         long total   0          for  int i 0  i  lt  SIZE  i                          total     first i  a0   1   0    second i  a0                    System out println total              private static long getMemory                 Runtime runtime   Runtime getRuntime            return runtime totalMemory   - runtime freeMemory              To reiterate  this is VM-dependent  but on my Windows laptop running Sun s JDK build 1 6 0 11 I got the following results   Size for LotsOfBooleans  87978576 Average size  87 978576 Size for LotsOfInts  328000000 Average size  328 0   That suggests that booleans can basically be packed into a byte each by Sun s JVM

User · Answer

I read that Java reserves one byte for a boolean datatype  but it uses only one bit  However  the documentation says that  its  size  isn t something that s precisely defined    See here

User · Answer

It s undefined  doing things like Jon Skeet suggested will get you an approximation on a given platform  but the way to know precisely for a specific platform is to use a profiler

User · Answer

The actual information represented by a boolean value in Java is one bit  1 for true  0 for false  However  the actual size of a boolean variable in memory is not precisely defined by the Java specification  See Primitive Data Types in Java      The boolean data type has only two   possible values  true and false  Use   this data type for simple flags that   track true false conditions  This data   type represents one bit of   information  but its  size  isn t   something that s precisely defined

User · Answer

It s virtual machine dependent

User · Answer

It s virtual machine dependent

User · Answer

On a side note     If you are thinking about using an array of Boolean objects  don t   Use a BitSet instead - it has some performance optimisations  and some nice extra methods  allowing you to get the next set unset bit

User · Answer

The actual information represented by a boolean value in Java is one bit  1 for true  0 for false  However  the actual size of a boolean variable in memory is not precisely defined by the Java specification  See Primitive Data Types in Java      The boolean data type has only two   possible values  true and false  Use   this data type for simple flags that   track true false conditions  This data   type represents one bit of   information  but its  size  isn t   something that s precisely defined

User · Answer

The boolean values are compiled to int data type in JVM  See here

User · Answer

The boolean values are compiled to int data type in JVM  See here

User · Answer

It s undefined  doing things like Jon Skeet suggested will get you an approximation on a given platform  but the way to know precisely for a specific platform is to use a profiler

User · Answer

The actual information represented by a boolean value in Java is one bit  1 for true  0 for false  However  the actual size of a boolean variable in memory is not precisely defined by the Java specification  See Primitive Data Types in Java      The boolean data type has only two   possible values  true and false  Use   this data type for simple flags that   track true false conditions  This data   type represents one bit of   information  but its  size  isn t   something that s precisely defined

User · Answer

It depends on the virtual machine  but it s easy to adapt the code from a similar question asking about bytes in Java   class LotsOfBooleans       boolean a0  a1  a2  a3  a4  a5  a6  a7  a8  a9  aa  ab  ac  ad  ae  af      boolean b0  b1  b2  b3  b4  b5  b6  b7  b8  b9  ba  bb  bc  bd  be  bf      boolean c0  c1  c2  c3  c4  c5  c6  c7  c8  c9  ca  cb  cc  cd  ce  cf      boolean d0  d1  d2  d3  d4  d5  d6  d7  d8  d9  da  db  dc  dd  de  df      boolean e0  e1  e2  e3  e4  e5  e6  e7  e8  e9  ea  eb  ec  ed  ee  ef     class LotsOfInts       int a0  a1  a2  a3  a4  a5  a6  a7  a8  a9  aa  ab  ac  ad  ae  af      int b0  b1  b2  b3  b4  b5  b6  b7  b8  b9  ba  bb  bc  bd  be  bf      int c0  c1  c2  c3  c4  c5  c6  c7  c8  c9  ca  cb  cc  cd  ce  cf      int d0  d1  d2  d3  d4  d5  d6  d7  d8  d9  da  db  dc  dd  de  df      int e0  e1  e2  e3  e4  e5  e6  e7  e8  e9  ea  eb  ec  ed  ee  ef      public class Test       private static final int SIZE   1000000       public static void main String   args  throws Exception                       LotsOfBooleans   first   new LotsOfBooleans SIZE           LotsOfInts   second   new LotsOfInts SIZE            System gc            long startMem   getMemory             for  int i 0  i  lt  SIZE  i                          first i    new LotsOfBooleans                       System gc            long endMem   getMemory             System out println   Size for LotsOfBooleans       endMem-startMem            System out println   Average size        endMem-startMem      double SIZE              System gc            startMem   getMemory            for  int i 0  i  lt  SIZE  i                          second i    new LotsOfInts                      System gc            endMem   getMemory             System out println   Size for LotsOfInts       endMem-startMem            System out println   Average size        endMem-startMem      double SIZE                 Make sure nothing gets collected         long total   0          for  int i 0  i  lt  SIZE  i                          total     first i  a0   1   0    second i  a0                    System out println total              private static long getMemory                 Runtime runtime   Runtime getRuntime            return runtime totalMemory   - runtime freeMemory              To reiterate  this is VM-dependent  but on my Windows laptop running Sun s JDK build 1 6 0 11 I got the following results   Size for LotsOfBooleans  87978576 Average size  87 978576 Size for LotsOfInts  328000000 Average size  328 0   That suggests that booleans can basically be packed into a byte each by Sun s JVM

User · Answer

It depends on the virtual machine  but it s easy to adapt the code from a similar question asking about bytes in Java   class LotsOfBooleans       boolean a0  a1  a2  a3  a4  a5  a6  a7  a8  a9  aa  ab  ac  ad  ae  af      boolean b0  b1  b2  b3  b4  b5  b6  b7  b8  b9  ba  bb  bc  bd  be  bf      boolean c0  c1  c2  c3  c4  c5  c6  c7  c8  c9  ca  cb  cc  cd  ce  cf      boolean d0  d1  d2  d3  d4  d5  d6  d7  d8  d9  da  db  dc  dd  de  df      boolean e0  e1  e2  e3  e4  e5  e6  e7  e8  e9  ea  eb  ec  ed  ee  ef     class LotsOfInts       int a0  a1  a2  a3  a4  a5  a6  a7  a8  a9  aa  ab  ac  ad  ae  af      int b0  b1  b2  b3  b4  b5  b6  b7  b8  b9  ba  bb  bc  bd  be  bf      int c0  c1  c2  c3  c4  c5  c6  c7  c8  c9  ca  cb  cc  cd  ce  cf      int d0  d1  d2  d3  d4  d5  d6  d7  d8  d9  da  db  dc  dd  de  df      int e0  e1  e2  e3  e4  e5  e6  e7  e8  e9  ea  eb  ec  ed  ee  ef      public class Test       private static final int SIZE   1000000       public static void main String   args  throws Exception                       LotsOfBooleans   first   new LotsOfBooleans SIZE           LotsOfInts   second   new LotsOfInts SIZE            System gc            long startMem   getMemory             for  int i 0  i  lt  SIZE  i                          first i    new LotsOfBooleans                       System gc            long endMem   getMemory             System out println   Size for LotsOfBooleans       endMem-startMem            System out println   Average size        endMem-startMem      double SIZE              System gc            startMem   getMemory            for  int i 0  i  lt  SIZE  i                          second i    new LotsOfInts                      System gc            endMem   getMemory             System out println   Size for LotsOfInts       endMem-startMem            System out println   Average size        endMem-startMem      double SIZE                 Make sure nothing gets collected         long total   0          for  int i 0  i  lt  SIZE  i                          total     first i  a0   1   0    second i  a0                    System out println total              private static long getMemory                 Runtime runtime   Runtime getRuntime            return runtime totalMemory   - runtime freeMemory              To reiterate  this is VM-dependent  but on my Windows laptop running Sun s JDK build 1 6 0 11 I got the following results   Size for LotsOfBooleans  87978576 Average size  87 978576 Size for LotsOfInts  328000000 Average size  328 0   That suggests that booleans can basically be packed into a byte each by Sun s JVM

User · Answer

On a side note     If you are thinking about using an array of Boolean objects  don t   Use a BitSet instead - it has some performance optimisations  and some nice extra methods  allowing you to get the next set unset bit

User · Answer

On a side note     If you are thinking about using an array of Boolean objects  don t   Use a BitSet instead - it has some performance optimisations  and some nice extra methods  allowing you to get the next set unset bit

User · Answer

The boolean values are compiled to int data type in JVM  See here

User · Answer

I read that Java reserves one byte for a boolean datatype  but it uses only one bit  However  the documentation says that  its  size  isn t something that s precisely defined    See here

User · Answer

Size of the boolean in java is virtual machine dependent  but Any Java object is aligned to an 8 bytes granularity  A Boolean has 8 bytes of header  plus 1 byte of payload  for a total of 9 bytes of information  The JVM then rounds it up to the next multiple of 8  so the one instance of java lang Boolean takes up 16 bytes of memory

[java] What is the size of a boolean variable in Java?

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