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painless-operators-boolean.md

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Operators: Boolean [painless-operators-boolean]

Boolean Not [boolean-not-operator]

Use the boolean not operator '!' to NOT a boolean type value where true is flipped to false and false is flipped to true.

Errors

  • If a value other than a boolean type value or a value that is castable to a boolean type value is given.

Truth

original result
true false
false true

Grammar

boolean_not: '!' expression;

Examples

  • Boolean not with the boolean type.

    boolean x = !false; <1>
boolean y = !x;     <2>
    1. declare boolean x; boolean not boolean false → boolean true; store boolean true to x
    2. declare boolean y; load from x → boolean true; boolean not boolean true → boolean false; store boolean false to y

  • Boolean not with the def type.

    def y = true; <1>
def z = !y;   <2>
    1. declare def y; implicit cast boolean true to def → def; store true to y
    2. declare def z; load from y → def; implicit cast def to boolean true → boolean true; boolean not boolean true → boolean false; implicit cast boolean false to def → def; store def to z

Greater Than [greater-than-operator]

Use the greater than operator '>' to COMPARE two numeric type values where a resultant boolean type value is true if the left-hand side value is greater than to the right-hand side value and false otherwise.

Errors

  • If either the evaluated left-hand side or the evaluated right-hand side is a non-numeric value.

Grammar

greater_than: expression '>' expression;

Promotion
byte short char int long float double def
byte int int int int long float double def
short int int int int long float double def
char int int int int long float double def
int int int int int long float double def
long long long long long long float double def
float float float float float float float double def
double double double double double double double double def
def def def def def def def def def

Examples

  • Greater than with different numeric types.

    boolean x = 5 > 4; <1>
double y = 6.0;    <2>
x = 6 > y;         <3>
    1. declare boolean x; greater than int 5 and int 4 → boolean true; store boolean true to x;
    2. declare double y; store double 6.0 to y;
    3. load from y → double 6.0 @0; promote int 6 and double 6.0: result double; implicit cast int 6 to double 6.0 @1 → double 6.0 @1; greater than double 6.0 @1 and double 6.0 @0 → boolean false; store boolean false to x

  • Greater than with def type.

    int x = 5;       <1>
def y = 7.0;     <2>
def z = y > 6.5; <3>
def a = x > y;   <4>
    1. declare int x; store int 5 to x
    2. declare def y; implicit cast double 7.0 to def → def; store def to y
    3. declare def z; load from y → def; implicit cast def to double 7.0 → double 7.0; greater than double 7.0 and double 6.5 → boolean true; implicit cast boolean true to def → def; store def to z
    4. declare def a; load from y → def; implicit cast def to double 7.0 → double 7.0; load from x → int 5; promote int 5 and double 7.0: result double; implicit cast int 5 to double 5.0 → double 5.0; greater than double 5.0 and double 7.0 → boolean false; implicit cast boolean false to def → def; store def to z

Greater Than Or Equal [greater-than-or-equal-operator]

Use the greater than or equal operator '>=' to COMPARE two numeric type values where a resultant boolean type value is true if the left-hand side value is greater than or equal to the right-hand side value and false otherwise.

Errors

  • If either the evaluated left-hand side or the evaluated right-hand side is a non-numeric value.

Grammar

greater_than_or_equal: expression '>=' expression;

Promotion
byte short char int long float double def
byte int int int int long float double def
short int int int int long float double def
char int int int int long float double def
int int int int int long float double def
long long long long long long float double def
float float float float float float float double def
double double double double double double double double def
def def def def def def def def def

Examples

  • Greater than or equal with different numeric types.

    boolean x = 5 >= 4; <1>
double y = 6.0;     <2>
x = 6 >= y;         <3>
    1. declare boolean x; greater than or equal int 5 and int 4 → boolean true; store boolean true to x
    2. declare double y; store double 6.0 to y
    3. load from y → double 6.0 @0; promote int 6 and double 6.0: result double; implicit cast int 6 to double 6.0 @1 → double 6.0 @1; greater than or equal double 6.0 @1 and double 6.0 @0 → boolean true; store boolean true to x

  • Greater than or equal with the def type.

    int x = 5;        <1>
def y = 7.0;      <2>
def z = y >= 7.0; <3>
def a = x >= y;   <4>
    1. declare int x; store int 5 to x;
    2. declare def y implicit cast double 7.0 to def → def; store def to y
    3. declare def z; load from y → def; implicit cast def to double 7.0 @0 → double 7.0 @0; greater than or equal double 7.0 @0 and double 7.0 @1 → boolean true; implicit cast boolean true to def → def; store def to z
    4. declare def a; load from y → def; implicit cast def to double 7.0 → double 7.0; load from x → int 5; promote int 5 and double 7.0: result double; implicit cast int 5 to double 5.0 → double 5.0; greater than or equal double 5.0 and double 7.0 → boolean false; implicit cast boolean false to def → def; store def to z

Less Than [less-than-operator]

Use the less than operator '<' to COMPARE two numeric type values where a resultant boolean type value is true if the left-hand side value is less than to the right-hand side value and false otherwise.

Errors

  • If either the evaluated left-hand side or the evaluated right-hand side is a non-numeric value.

Grammar

less_than: expression '<' expression;

Promotion
byte short char int long float double def
byte int int int int long float double def
short int int int int long float double def
char int int int int long float double def
int int int int int long float double def
long long long long long long float double def
float float float float float float float double def
double double double double double double double double def
def def def def def def def def def

Examples

  • Less than with different numeric types.

    boolean x = 5 < 4; <1>
double y = 6.0;    <2>
x = 6 < y;         <3>
    1. declare boolean x; less than int 5 and int 4 → boolean false; store boolean false to x
    2. declare double y; store double 6.0 to y
    3. load from y → double 6.0 @0; promote int 6 and double 6.0: result double; implicit cast int 6 to double 6.0 @1 → double 6.0 @1; less than double 6.0 @1 and double 6.0 @0 → boolean false; store boolean false to x

  • Less than with the def type.

    int x = 5;       <1>
def y = 7.0;     <2>
def z = y < 6.5; <3>
def a = x < y;   <4>
    1. declare int x; store int 5 to x
    2. declare def y; implicit cast double 7.0 to def → def; store def to y
    3. declare def z; load from y → def; implicit cast def to double 7.0 → double 7.0; less than double 7.0 and double 6.5 → boolean false; implicit cast boolean false to def → def; store def to z
    4. declare def a; load from y → def; implicit cast def to double 7.0 → double 7.0; load from x → int 5; promote int 5 and double 7.0: result double; implicit cast int 5 to double 5.0 → double 5.0; less than double 5.0 and double 7.0 → boolean true; implicit cast boolean true to def → def; store def to z

Less Than Or Equal [less-than-or-equal-operator]

Use the less than or equal operator '<=' to COMPARE two numeric type values where a resultant boolean type value is true if the left-hand side value is less than or equal to the right-hand side value and false otherwise.

Errors

  • If either the evaluated left-hand side or the evaluated right-hand side is a non-numeric value.

Grammar

greater_than_or_equal: expression '<=' expression;

Promotion
byte short char int long float double def
byte int int int int long float double def
short int int int int long float double def
char int int int int long float double def
int int int int int long float double def
long long long long long long float double def
float float float float float float float double def
double double double double double double double double def
def def def def def def def def def

Examples

  • Less than or equal with different numeric types.

    boolean x = 5 <= 4; <1>
double y = 6.0;     <2>
x = 6 <= y;         <3>
    1. declare boolean x; less than or equal int 5 and int 4 → boolean false; store boolean true to x
    2. declare double y; store double 6.0 to y
    3. load from y → double 6.0 @0; promote int 6 and double 6.0: result double; implicit cast int 6 to double 6.0 @1 → double 6.0 @1; less than or equal double 6.0 @1 and double 6.0 @0 → boolean true; store boolean true to x

  • Less than or equal with the def type.

    int x = 5;        <1>
def y = 7.0;      <2>
def z = y <= 7.0; <3>
def a = x <= y;   <4>
    1. declare int x; store int 5 to x;
    2. declare def y; implicit cast double 7.0 to def → def; store def to y;
    3. declare def z; load from y → def; implicit cast def to double 7.0 @0 → double 7.0 @0; less than or equal double 7.0 @0 and double 7.0 @1 → boolean true; implicit cast boolean true to def → def; store def to z
    4. declare def a; load from y → def; implicit cast def to double 7.0 → double 7.0; load from x → int 5; promote int 5 and double 7.0: result double; implicit cast int 5 to double 5.0 → double 5.0; less than or equal double 5.0 and double 7.0 → boolean true; implicit cast boolean true to def → def; store def to z

Instanceof [instanceof-operator]

Use the instanceof operator to COMPARE the variable/field type to a specified reference type using the reference type name where a resultant boolean type value is true if the variable/field type is the same as or a descendant of the specified reference type and false otherwise.

Errors

  • If the reference type name doesn’t exist as specified by the right-hand side.

Grammar

instance_of: ID 'instanceof' TYPE;

Examples

  • Instance of with different reference types.

    Map m = new HashMap();            <1>
boolean a = m instanceof HashMap; <2>
boolean b = m instanceof Map;     <3>
    1. declare Map m; allocate HashMap instance → HashMap reference; implicit cast HashMap reference to Map reference; store Map reference to m
    2. declare boolean a; load from m → Map reference; implicit cast Map reference to HashMap reference → HashMap reference; instanceof HashMap reference and HashMap → boolean true; store boolean true to a
    3. declare boolean b; load from m → Map reference; implicit cast Map reference to HashMap reference → HashMap reference; instanceof HashMap reference and Map → boolean true; store true to b; (note HashMap is a descendant of Map)

  • Instance of with the def type.

    def d = new ArrayList();       <1>
boolean a = d instanceof List; <2>
boolean b = d instanceof Map;  <3>
    1. declare def d; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to def → def; store def to d
    2. declare boolean a; load from d → def; implicit cast def to ArrayList reference → ArrayList reference; instanceof ArrayList reference and List → boolean true; store boolean true to a; (note ArrayList is a descendant of List)
    3. declare boolean b; load from d → def; implicit cast def to ArrayList reference → ArrayList reference; instanceof ArrayList reference and Map → boolean false; store boolean false to a; (note ArrayList is not a descendant of Map)

Equality Equals [equality-equals-operator]

Use the equality equals operator '==' to COMPARE two values where a resultant boolean type value is true if the two values are equal and false otherwise. The member method, equals, is implicitly called when the values are reference type values where the first value is the target of the call and the second value is the argument. This operation is null-safe where if both values are null the resultant boolean type value is true, and if only one value is null the resultant boolean type value is false. A valid comparison is between boolean type values, numeric type values, or reference type values.

Errors

  • If a comparison is made between a boolean type value and numeric type value.
  • If a comparison is made between a primitive type value and a reference type value.

Grammar

equality_equals: expression '==' expression;

Promotion
boolean byte short char int long float double Reference def
boolean boolean - - - - - - - - def
byte - int int int int long float double - def
short - int int int int long float double - def
char - int int int int long float double - def
int - int int int int long float double - def
long - long long long long long float double - def
float - float float float float float float double - def
double - double double double double double double double - def
Reference - - - - - - - - Object def
def def def def def def def def def def def

Examples

  • Equality equals with the boolean type.

    boolean a = true;  <1>
boolean b = false; <2>
a = a == false;    <3>
b = a == b;        <4>
    1. declare boolean a; store boolean true to a
    2. declare boolean b; store boolean false to b
    3. load from a → boolean true; equality equals boolean true and boolean false → boolean false; store boolean false to a
    4. load from a → boolean false @0; load from b → boolean false @1; equality equals boolean false @0 and boolean false @1 → boolean false; store boolean false to b

  • Equality equals with primitive types.

    int a = 1;          <1>
double b = 2.0;     <2>
boolean c = a == b; <3>
c = 1 == a;         <4>
    1. declare int a; store int 1 to a
    2. declare double b; store double 1.0 to b
    3. declare boolean c; load from a → int 1; load from b → double 2.0; promote int 1 and double 2.0: result double; implicit cast int 1 to double 1.0 → double1.0; equality equalsdouble 1.0anddouble 2.0→boolean false; storeboolean falsetoc`
    4. load from a → int 1 @1; equality equals int 1 @0 and int 1 @1 → boolean true; store boolean true to c

  • Equal equals with reference types.

    List a = new ArrayList(); <1>
List b = new ArrayList(); <2>
a.add(1);                 <3>
boolean c = a == b;       <4>
b.add(1);                 <5>
c = a == b;               <6>
    1. declare List a; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to List reference → List reference; store List reference to a
    2. declare List b; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to List reference → List reference; store List reference to b
    3. load from a → List reference; call add on List reference with arguments (int 1)
    4. declare boolean c; load from a → List reference @0; load from b → List reference @1; call equals on List reference @0 with arguments (List reference @1) → boolean false; store boolean false to c
    5. load from b → List reference; call add on List reference with arguments (int 1)
    6. load from a → List reference @0; load from b → List reference @1; call equals on List reference @0 with arguments (List reference @1) → boolean true; store boolean true to c

  • Equality equals with null.

    Object a = null;       <1>
Object b = null;       <2>
boolean c = a == null; <3>
c = a == b;            <4>
b = new Object();      <5>
c = a == b;            <6>
    1. declare Object a; store null to a
    2. declare Object b; store null to b
    3. declare boolean c; load from a → null @0; equality equals null @0 and null @1 → boolean true; store boolean true to c
    4. load from a → null @0; load from b → null @1; equality equals null @0 and null @1 → boolean true; store boolean true to c
    5. allocate Object instance → Object reference; store Object reference to b
    6. load from a → Object reference; load from b → null; call equals on Object reference with arguments (null) → boolean false; store boolean false to c

  • Equality equals with the def type.

    def a = 0;               <1>
def b = 1;               <2>
boolean c = a == b;      <3>
def d = new HashMap();   <4>
def e = new ArrayList(); <5>
c = d == e;              <6>
    1. declare def a; implicit cast int 0 to def → def; store def to a;
    2. declare def b; implicit cast int 1 to def → def; store def to b;
    3. declare boolean c; load from a → def; implicit cast a to int 0 → int 0; load from b → def; implicit cast b to int 1 → int 1; equality equals int 0 and int 1 → boolean false; store boolean false to c
    4. declare def d; allocate HashMap instance → HashMap reference; implicit cast HashMap reference to def → def store def to d;
    5. declare def e; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to def → def store def to d;
    6. load from d → def; implicit cast def to HashMap reference → HashMap reference; load from e → def; implicit cast def to ArrayList reference → ArrayList reference; call equals on HashMap reference with arguments (ArrayList reference) → boolean false; store boolean false to c

Equality Not Equals [equality-not-equals-operator]

Use the equality not equals operator '!=' to COMPARE two values where a resultant boolean type value is true if the two values are NOT equal and false otherwise. The member method, equals, is implicitly called when the values are reference type values where the first value is the target of the call and the second value is the argument with the resultant boolean type value flipped. This operation is null-safe where if both values are null the resultant boolean type value is false, and if only one value is null the resultant boolean type value is true. A valid comparison is between boolean type values, numeric type values, or reference type values.

Errors

  • If a comparison is made between a boolean type value and numeric type value.
  • If a comparison is made between a primitive type value and a reference type value.

Grammar

equality_not_equals: expression '!=' expression;

Promotion
boolean byte short char int long float double Reference def
boolean boolean - - - - - - - - def
byte - int int int int long float double - def
short - int int int int long float double - def
char - int int int int long float double - def
int - int int int int long float double - def
long - long long long long long float double - def
float - float float float float float float double - def
double - double double double double double double double - def
Reference - - - - - - - - Object def
def def def def def def def def def def def

Examples

  • Equality not equals with the boolean type.

    boolean a = true;  <1>
boolean b = false; <2>
a = a != false;    <3>
b = a != b;        <4>
    1. declare boolean a; store boolean true to a
    2. declare boolean b; store boolean false to b
    3. load from a → boolean true; equality not equals boolean true and boolean false → boolean true; store boolean true to a
    4. load from a → boolean true; load from b → boolean false; equality not equals boolean true and boolean false → boolean true; store boolean true to b

  • Equality not equals with primitive types.

    int a = 1;          <1>
double b = 2.0;     <2>
boolean c = a != b; <3>
c = 1 != a;         <4>
    1. declare int a; store int 1 to a
    2. declare double b; store double 1.0 to b
    3. declare boolean c; load from a → int 1; load from b → double 2.0; promote int 1 and double 2.0: result double; implicit cast int 1 to double 1.0 → double1.0; equality not equalsdouble 1.0anddouble 2.0→boolean true; storeboolean truetoc`
    4. load from a → int 1 @1; equality not equals int 1 @0 and int 1 @1 → boolean false; store boolean false to c

  • Equality not equals with reference types.

    List a = new ArrayList(); <1>
List b = new ArrayList(); <2>
a.add(1);                 <3>
boolean c = a == b;       <4>
b.add(1);                 <5>
c = a == b;               <6>
    1. declare List a; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to List reference → List reference; store List reference to a
    2. declare List b; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to List reference → List reference; store List reference to b
    3. load from a → List reference; call add on List reference with arguments (int 1)
    4. declare boolean c; load from a → List reference @0; load from b → List reference @1; call equals on List reference @0 with arguments (List reference @1) → boolean false; boolean not boolean false → boolean true store boolean true to c
    5. load from b → List reference; call add on List reference with arguments (int 1)
    6. load from a → List reference @0; load from b → List reference @1; call equals on List reference @0 with arguments (List reference @1) → boolean true; boolean not boolean true → boolean false; store boolean false to c

  • Equality not equals with null.

    Object a = null;       <1>
Object b = null;       <2>
boolean c = a == null; <3>
c = a == b;            <4>
b = new Object();      <5>
c = a == b;            <6>
    1. declare Object a; store null to a
    2. declare Object b; store null to b
    3. declare boolean c; load from a → null @0; equality not equals null @0 and null @1 → boolean false; store boolean false to c
    4. load from a → null @0; load from b → null @1; equality not equals null @0 and null @1 → boolean false; store boolean false to c
    5. allocate Object instance → Object reference; store Object reference to b
    6. load from a → Object reference; load from b → null; call equals on Object reference with arguments (null) → boolean false; boolean not boolean false → boolean true; store boolean true to c

  • Equality not equals with the def type.

    def a = 0;               <1>
def b = 1;               <2>
boolean c = a == b;      <3>
def d = new HashMap();   <4>
def e = new ArrayList(); <5>
c = d == e;              <6>
    1. declare def a; implicit cast int 0 to def → def; store def to a;
    2. declare def b; implicit cast int 1 to def → def; store def to b;
    3. declare boolean c; load from a → def; implicit cast a to int 0 → int 0; load from b → def; implicit cast b to int 1 → int 1; equality equals int 0 and int 1 → boolean false; store boolean false to c
    4. declare def d; allocate HashMap instance → HashMap reference; implicit cast HashMap reference to def → def store def to d;
    5. declare def e; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to def → def store def to d;
    6. load from d → def; implicit cast def to HashMap reference → HashMap reference; load from e → def; implicit cast def to ArrayList reference → ArrayList reference; call equals on HashMap reference with arguments (ArrayList reference) → boolean false; store boolean false to c

Identity Equals [identity-equals-operator]

Use the identity equals operator '===' to COMPARE two values where a resultant boolean type value is true if the two values are equal and false otherwise. A reference type value is equal to another reference type value if both values refer to same instance on the heap or if both values are null. A valid comparison is between boolean type values, numeric type values, or reference type values.

Errors

  • If a comparison is made between a boolean type value and numeric type value.
  • If a comparison is made between a primitive type value and a reference type value.

Grammar

identity_equals: expression '===' expression;

Promotion
boolean byte short char int long float double Reference def
boolean boolean - - - - - - - - def
byte - int int int int long float double - def
short - int int int int long float double - def
char - int int int int long float double - def
int - int int int int long float double - def
long - long long long long long float double - def
float - float float float float float float double - def
double - double double double double double double double - def
Reference - - - - - - - - Object def
def def def def def def def def def def def

Examples

  • Identity equals with reference types.

    List a = new ArrayList(); <1>
List b = new ArrayList(); <2>
List c = a;               <3>
boolean c = a === b;      <4>
c = a === c;              <5>
    1. declare List a; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to List reference → List reference; store List reference to a
    2. declare List b; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to List reference → List reference; store List reference to b
    3. load from a → List reference; store List reference to c
    4. declare boolean c; load from a → List reference @0; load from b → List reference @1; identity equals List reference @0 and List reference @1 → boolean false store boolean false to c
    5. load from a → List reference @0; load from c → List reference @1; identity equals List reference @0 and List reference @1 → boolean true store boolean true to c (note List reference @0 and List reference @1 refer to the same instance)

  • Identity equals with null.

    Object a = null;        <1>
Object b = null;        <2>
boolean c = a === null; <3>
c = a === b;            <4>
b = new Object();       <5>
c = a === b;            <6>
    1. declare Object a; store null to a
    2. declare Object b; store null to b
    3. declare boolean c; load from a → null @0; identity equals null @0 and null @1 → boolean true; store boolean true to c
    4. load from a → null @0; load from b → null @1; identity equals null @0 and null @1 → boolean true; store boolean true to c
    5. allocate Object instance → Object reference; store Object reference to b
    6. load from a → Object reference; load from b → null; identity equals Object reference and null → boolean false; store boolean false to c

  • Identity equals with the def type.

    def a = new HashMap();   <1>
def b = new ArrayList(); <2>
boolean c = a === b;     <3>
b = a;                   <4>
c = a === b;             <5>
    1. declare def d; allocate HashMap instance → HashMap reference; implicit cast HashMap reference to def → def store def to d
    2. declare def e; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to def → def store def to d
    3. declare boolean c; load from a → def; implicit cast def to HashMap reference → HashMap reference; load from b → def; implicit cast def to ArrayList reference → ArrayList reference; identity equals HashMap reference and ArrayList reference → boolean false; store boolean false to c
    4. load from a → def; store def to b
    5. load from a → def; implicit cast def to HashMap reference @0 → HashMap reference @0; load from b → def; implicit cast def to HashMap reference @1 → HashMap reference @1; identity equals HashMap reference @0 and HashMap reference @1 → boolean true; store boolean true to b; (note HashMap reference @0 and HashMap reference @1 refer to the same instance)

Identity Not Equals [identity-not-equals-operator]

Use the identity not equals operator '!==' to COMPARE two values where a resultant boolean type value is true if the two values are NOT equal and false otherwise. A reference type value is not equal to another reference type value if both values refer to different instances on the heap or if one value is null and the other is not. A valid comparison is between boolean type values, numeric type values, or reference type values.

Errors

  • If a comparison is made between a boolean type value and numeric type value.
  • If a comparison is made between a primitive type value and a reference type value.

Grammar

identity_not_equals: expression '!==' expression;

Promotion
boolean byte short char int long float double Reference def
boolean boolean - - - - - - - - def
byte - int int int int long float double - def
short - int int int int long float double - def
char - int int int int long float double - def
int - int int int int long float double - def
long - long long long long long float double - def
float - float float float float float float double - def
double - double double double double double double double - def
Reference - - - - - - - - Object def
def def def def def def def def def def def

Examples

  • Identity not equals with reference type values.

    List a = new ArrayList(); <1>
List b = new ArrayList(); <2>
List c = a;               <3>
boolean c = a !== b;      <4>
c = a !== c;              <5>
    1. declare List a; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to List reference → List reference; store List reference to a
    2. declare List b; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to List reference → List reference; store List reference to b
    3. load from a → List reference; store List reference to c
    4. declare boolean c; load from a → List reference @0; load from b → List reference @1; identity not equals List reference @0 and List reference @1 → boolean true store boolean true to c
    5. load from a → List reference @0; load from c → List reference @1; identity not equals List reference @0 and List reference @1 → boolean false store boolean false to c (note List reference @0 and List reference @1 refer to the same instance)

  • Identity not equals with null.

    Object a = null;        <1>
Object b = null;        <2>
boolean c = a !== null; <3>
c = a !== b;            <4>
b = new Object();       <5>
c = a !== b;            <6>
    1. declare Object a; store null to a
    2. declare Object b; store null to b
    3. declare boolean c; load from a → null @0; identity not equals null @0 and null @1 → boolean false; store boolean false to c
    4. load from a → null @0; load from b → null @1; identity not equals null @0 and null @1 → boolean false; store boolean false to c
    5. allocate Object instance → Object reference; store Object reference to b
    6. load from a → Object reference; load from b → null; identity not equals Object reference and null → boolean true; store boolean true to c

  • Identity not equals with the def type.

    def a = new HashMap();   <1>
def b = new ArrayList(); <2>
boolean c = a !== b;     <3>
b = a;                   <4>
c = a !== b;             <5>
    1. declare def d; allocate HashMap instance → HashMap reference; implicit cast HashMap reference to def → def store def to d
    2. declare def e; allocate ArrayList instance → ArrayList reference; implicit cast ArrayList reference to def → def store def to d
    3. declare boolean c; load from a → def; implicit cast def to HashMap reference → HashMap reference; load from b → def; implicit cast def to ArrayList reference → ArrayList reference; identity not equals HashMap reference and ArrayList reference → boolean true; store boolean true to c
    4. load from a → def; store def to b
    5. load from a → def; implicit cast def to HashMap reference @0 → HashMap reference @0; load from b → def; implicit cast def to HashMap reference @1 → HashMap reference @1; identity not equals HashMap reference @0 and HashMap reference @1 → boolean false; store boolean false to b; (note HashMap reference @0 and HashMap reference @1 refer to the same instance)

Boolean Xor [boolean-xor-operator]

Use the boolean xor operator '^' to XOR together two boolean type values where if one boolean type value is true and the other is false the resultant boolean type value is true and false otherwise.

Errors

  • If either evaluated value is a value other than a boolean type value or a value that is castable to a boolean type value.

Truth
true false
true false true
false true false

Grammar

boolean_xor: expression '^' expression;

Examples

  • Boolean xor with the boolean type.

    boolean x = false;    <1>
boolean y = x ^ true; <2>
y = y ^ x;            <3>
    1. declare boolean x; store boolean false to x
    2. declare boolean y; load from x → boolean false boolean xor boolean false and boolean true → boolean true; store boolean true to y
    3. load from y → boolean true @0; load from x → boolean true @1; boolean xor boolean true @0 and boolean true @1 → boolean false; store boolean false to y

  • Boolean xor with the def type.

    def x = false;    <1>
def y = x ^ true; <2>
y = y ^ x;        <3>
    1. declare def x; implicit cast boolean false to def → def; store def to x
    2. declare def y; load from x → def; implicit cast def to boolean false → boolean false; boolean xor boolean false and boolean true → boolean true; implicit cast boolean true to def → def; store def to y
    3. load from y → def; implicit cast def to boolean true @0 → boolean true @0; load from x → def; implicit cast def to boolean true @1 → boolean true @1; boolean xor boolean true @0 and boolean true @1 → boolean false; implicit cast boolean false → def; store def to y

Boolean And [boolean-and-operator]

Use the boolean and operator '&&' to AND together two boolean type values where if both boolean type values are true the resultant boolean type value is true and false otherwise.

Errors

  • If either evaluated value is a value other than a boolean type value or a value that is castable to a boolean type value.

Truth
true false
true true false
false false false

Grammar

boolean_and: expression '&&' expression;

Examples

  • Boolean and with the boolean type.

    boolean x = true;      <1>
boolean y = x && true; <2>
x = false;             <3>
y = y && x;            <4>
    1. declare boolean x; store boolean true to x
    2. declare boolean y; load from x → boolean true @0; boolean and boolean true @0 and boolean true @1 → boolean true; store boolean true to y
    3. store boolean false to x
    4. load from y → boolean true; load from x → boolean false; boolean and boolean true and boolean false → boolean false; store boolean false to y

  • Boolean and with the def type.

    def x = true;      <1>
def y = x && true; <2>
x = false;         <3>
y = y && x;        <4>
    1. declare def x; implicit cast boolean true to def → def; store def to x
    2. declare def y; load from x → def; implicit cast def to boolean true @0 → boolean true @0; boolean and boolean true @0 and boolean true @1 → boolean true; implicit cast boolean true to def → def; store def to y
    3. implicit cast boolean false to def → def; store def to x;
    4. load from y → def; implicit cast def to boolean true → boolean true; load from x → def; implicit cast def to boolean false → boolean false; boolean and boolean true and boolean false → boolean false; implicit cast boolean false → def; store def to y

Boolean Or [boolean-or-operator]

Use the boolean or operator '||' to OR together two boolean type values where if either one of the boolean type values is true the resultant boolean type value is true and false otherwise.

Errors

  • If either evaluated value is a value other than a boolean type value or a value that is castable to a boolean type value.

Truth
true false
true true true
false true false

Grammar:

boolean_and: expression '||' expression;

Examples

  • Boolean or with the boolean type.

    boolean x = false;     <1>
boolean y = x || true; <2>
y = false;             <3>
y = y || x;            <4>
    1. declare boolean x; store boolean false to x
    2. declare boolean y; load from x → boolean false; boolean or boolean false and boolean true → boolean true; store boolean true to y
    3. store boolean false to y
    4. load from y → boolean false @0; load from x → boolean false @1; boolean or boolean false @0 and boolean false @1 → boolean false; store boolean false to y

  • Boolean or with the def type.

    def x = false;     <1>
def y = x || true; <2>
y = false;         <3>
y = y || x;        <4>
    1. declare def x; implicit cast boolean false to def → def; store def to x
    2. declare def y; load from x → def; implicit cast def to boolean false → boolean true; boolean or boolean false and boolean true → boolean true; implicit cast boolean true to def → def; store def to y
    3. implicit cast boolean false to def → def; store def to y;
    4. load from y → def; implicit cast def to boolean false @0 → boolean false @0; load from x → def; implicit cast def to boolean false @1 → boolean false @1; boolean or boolean false @0 and boolean false @1 → boolean false; implicit cast boolean false → def; store def to y