Return first element of array, in a def
Can you please help me understand, why the second def is not compiling, and how to write the second def for that it is compiling (return first entry of Array in one line). Thanks!
import java.awt.{GraphicsDevice, GraphicsEnvironment}
class SeparatedTestCase {
def does_compile: GraphicsDevice = {
val ge: GraphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment
val devices: Array[GraphicsDevice] = ge.getScreenDevices
devices(0)
}
def does_not_compile: GraphicsDevice = {
val ge: GraphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment
val device0: GraphicsDevice = (ge.getScreenDevices)(0) // <---- compile error
device0
}
}
//Error:(13, 59) no arguments allowed for nullary method getScreenDevices: ()Array[java.awt.GraphicsDevice]
//val device0: GraphicsDevice = (ge.getScreenDevices)(0)
scala
asked Nov 14 '18 at 1:03
Hartmut P.Hartmut P.
2,03722429
add a comment |
Can you please help me understand, why the second def is not compiling, and how to write the second def for that it is compiling (return first entry of Array in one line). Thanks!
import java.awt.{GraphicsDevice, GraphicsEnvironment}
class SeparatedTestCase {
def does_compile: GraphicsDevice = {
val ge: GraphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment
val devices: Array[GraphicsDevice] = ge.getScreenDevices
devices(0)
}
def does_not_compile: GraphicsDevice = {
val ge: GraphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment
val device0: GraphicsDevice = (ge.getScreenDevices)(0) // <---- compile error
device0
}
}
//Error:(13, 59) no arguments allowed for nullary method getScreenDevices: ()Array[java.awt.GraphicsDevice]
//val device0: GraphicsDevice = (ge.getScreenDevices)(0)
scala
asked Nov 14 '18 at 1:03
Hartmut P.Hartmut P.
2,03722429
add a comment |
Can you please help me understand, why the second def is not compiling, and how to write the second def for that it is compiling (return first entry of Array in one line). Thanks!
import java.awt.{GraphicsDevice, GraphicsEnvironment}
class SeparatedTestCase {
def does_compile: GraphicsDevice = {
val ge: GraphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment
val devices: Array[GraphicsDevice] = ge.getScreenDevices
devices(0)
}
def does_not_compile: GraphicsDevice = {
val ge: GraphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment
val device0: GraphicsDevice = (ge.getScreenDevices)(0) // <---- compile error
device0
}
}
//Error:(13, 59) no arguments allowed for nullary method getScreenDevices: ()Array[java.awt.GraphicsDevice]
//val device0: GraphicsDevice = (ge.getScreenDevices)(0)
scala
asked Nov 14 '18 at 1:03
Hartmut P.Hartmut P.
2,03722429
Can you please help me understand, why the second def is not compiling, and how to write the second def for that it is compiling (return first entry of Array in one line). Thanks!
import java.awt.{GraphicsDevice, GraphicsEnvironment}
class SeparatedTestCase {
def does_compile: GraphicsDevice = {
val ge: GraphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment
val devices: Array[GraphicsDevice] = ge.getScreenDevices
devices(0)
}
def does_not_compile: GraphicsDevice = {
val ge: GraphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment
val device0: GraphicsDevice = (ge.getScreenDevices)(0) // <---- compile error
device0
}
}
//Error:(13, 59) no arguments allowed for nullary method getScreenDevices: ()Array[java.awt.GraphicsDevice]
//val device0: GraphicsDevice = (ge.getScreenDevices)(0)
scala
scala
asked Nov 14 '18 at 1:03
Hartmut P.Hartmut P.
2,03722429
asked Nov 14 '18 at 1:03
Hartmut P.Hartmut P.
2,03722429
asked Nov 14 '18 at 1:03
Hartmut P.Hartmut P.
2,03722429
asked Nov 14 '18 at 1:03
Hartmut P.Hartmut P.
2,03722429
asked Nov 14 '18 at 1:03
Hartmut P.Hartmut P.
2,03722429
2,03722429
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
You have to invoke the method with explicit parentheses:
ge.getScreenDevices()(0)
This does not compile, because your second invocation means the same as
ge.getScreenDevices(0)
which does not do what you want because getScreenDevices is a Java null-ary method which can be invoked either with parentheses or not, and if you specify one set of parentheses, Scala assumes that you want to invoke this method with these parameters, which of course won't work since it does not accept any arguments.
answered Nov 14 '18 at 1:05
Vladimir MatveevVladimir Matveev
69.8k15170213
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You have to invoke the method with explicit parentheses:
ge.getScreenDevices()(0)
This does not compile, because your second invocation means the same as
ge.getScreenDevices(0)
which does not do what you want because getScreenDevices is a Java null-ary method which can be invoked either with parentheses or not, and if you specify one set of parentheses, Scala assumes that you want to invoke this method with these parameters, which of course won't work since it does not accept any arguments.
answered Nov 14 '18 at 1:05
Vladimir MatveevVladimir Matveev
69.8k15170213
add a comment |
You have to invoke the method with explicit parentheses:
ge.getScreenDevices()(0)
This does not compile, because your second invocation means the same as
ge.getScreenDevices(0)
which does not do what you want because getScreenDevices is a Java null-ary method which can be invoked either with parentheses or not, and if you specify one set of parentheses, Scala assumes that you want to invoke this method with these parameters, which of course won't work since it does not accept any arguments.
answered Nov 14 '18 at 1:05
Vladimir MatveevVladimir Matveev
69.8k15170213
add a comment |
You have to invoke the method with explicit parentheses:
ge.getScreenDevices()(0)
This does not compile, because your second invocation means the same as
ge.getScreenDevices(0)
which does not do what you want because getScreenDevices is a Java null-ary method which can be invoked either with parentheses or not, and if you specify one set of parentheses, Scala assumes that you want to invoke this method with these parameters, which of course won't work since it does not accept any arguments.
answered Nov 14 '18 at 1:05
Vladimir MatveevVladimir Matveev
69.8k15170213
You have to invoke the method with explicit parentheses:
ge.getScreenDevices()(0)
This does not compile, because your second invocation means the same as
ge.getScreenDevices(0)
which does not do what you want because getScreenDevices is a Java null-ary method which can be invoked either with parentheses or not, and if you specify one set of parentheses, Scala assumes that you want to invoke this method with these parameters, which of course won't work since it does not accept any arguments.
answered Nov 14 '18 at 1:05
Vladimir MatveevVladimir Matveev
69.8k15170213
answered Nov 14 '18 at 1:05
Vladimir MatveevVladimir Matveev
69.8k15170213
answered Nov 14 '18 at 1:05
Vladimir MatveevVladimir Matveev
69.8k15170213
answered Nov 14 '18 at 1:05
Vladimir MatveevVladimir Matveev
69.8k15170213
69.8k15170213
add a comment |
add a comment |
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