casting

问题 Consider this Minimal, Reproducible Example : interface Code { static void main(String[] args) { symbol( String.valueOf( true ? 'a' : true ? 'b' : true ? 'c' : fail() ) ); } private static void symbol(String symbol) { System.out.println(symbol); } private static <R> R fail() { throw null; } } (Being near minimal, true is a stand in for a useful boolean expression. We can ignore beyond the first ? : (in the real code, there are lots).) This 'obviously' gives the error. 4: reference to valueOf

问题 Consider this Minimal, Reproducible Example : interface Code { static void main(String[] args) { symbol( String.valueOf( true ? 'a' : true ? 'b' : true ? 'c' : fail() ) ); } private static void symbol(String symbol) { System.out.println(symbol); } private static <R> R fail() { throw null; } } (Being near minimal, true is a stand in for a useful boolean expression. We can ignore beyond the first ? : (in the real code, there are lots).) This 'obviously' gives the error. 4: reference to valueOf

问题 I have this code: List<Widget> _elementsHere = _locationsRegister .map((e) => ShowingLocation( num: e.num, name: e.name, icon: e.icon, )) .toList(); I have specified List<Widget> , but if I print _elementsHere.runtimeType.toString() in console, I can see List<ShowingLocation> . In fact if I add this code: _elementsHere.insert(0, Text('hello')); I receive error that Text isn't a subtype of ShowingLocation , despite it's a Widget. I want _elementsHere as List<Widget> instead of List

问题 Why is it that casting (int) can convert chars of a symbol to int properly, but "Character.getNumericValue('someSymbolCharValue');" can't? E.g. "Character.getNumericValue('?');" will return -1 even though the char can be presented as int with " (int) '?' " where it will return 63 回答1: A character's "numeric value" is not its ASCII/Unicode index value. The Character.getNumericValue method will attempt to convert the char to an int by applying the character's numeric meaning: Returns the int

问题 Why is it that casting (int) can convert chars of a symbol to int properly, but "Character.getNumericValue('someSymbolCharValue');" can't? E.g. "Character.getNumericValue('?');" will return -1 even though the char can be presented as int with " (int) '?' " where it will return 63 回答1: A character's "numeric value" is not its ASCII/Unicode index value. The Character.getNumericValue method will attempt to convert the char to an int by applying the character's numeric meaning: Returns the int

问题 I want to sort floats in C with radix. Below is the code I have. However, my output is not correct. For example, if I run the code with 3.1, -5, and 1 my sorted values are printed as 3.000000, -5.000000, and 1.000000. I know to cast correctly from a float to an int back to a float, I need to apply the following logic but I am not sure how to integrate this into rfloat() because I tried and am getting many errors. How would I be able to correctly apply a bitwise radix sort to floats? float x =

问题 There does not seem to be an obvious way: select 'a123'::text::jsonb = ERROR: invalid input syntax for type json select '"a123"'::text::jsonb = BAD string because quoted check select '"a123"'::text::jsonb = ('{"x":"a123"}'::jsonb)->'x' to see that non-quoted is the correct . select '123'::text::jsonb = ('{"x":123}'::jsonb)->'x'; = NOT string I need '123' and 'a123' as pure JSONb strings . PS: it is not a duplicate of generic automatic-anything conversion. 回答1: To convert untyped string

问题 There does not seem to be an obvious way: select 'a123'::text::jsonb = ERROR: invalid input syntax for type json select '"a123"'::text::jsonb = BAD string because quoted check select '"a123"'::text::jsonb = ('{"x":"a123"}'::jsonb)->'x' to see that non-quoted is the correct . select '123'::text::jsonb = ('{"x":123}'::jsonb)->'x'; = NOT string I need '123' and 'a123' as pure JSONb strings . PS: it is not a duplicate of generic automatic-anything conversion. 回答1: To convert untyped string

问题 There does not seem to be an obvious way: select 'a123'::text::jsonb = ERROR: invalid input syntax for type json select '"a123"'::text::jsonb = BAD string because quoted check select '"a123"'::text::jsonb = ('{"x":"a123"}'::jsonb)->'x' to see that non-quoted is the correct . select '123'::text::jsonb = ('{"x":123}'::jsonb)->'x'; = NOT string I need '123' and 'a123' as pure JSONb strings . PS: it is not a duplicate of generic automatic-anything conversion. 回答1: To convert untyped string

问题 There does not seem to be an obvious way: select 'a123'::text::jsonb = ERROR: invalid input syntax for type json select '"a123"'::text::jsonb = BAD string because quoted check select '"a123"'::text::jsonb = ('{"x":"a123"}'::jsonb)->'x' to see that non-quoted is the correct . select '123'::text::jsonb = ('{"x":123}'::jsonb)->'x'; = NOT string I need '123' and 'a123' as pure JSONb strings . PS: it is not a duplicate of generic automatic-anything conversion. 回答1: To convert untyped string