Whats the meaning of Java::JavaxSwingJTable.new

Ruby JRuby
1

Since I just stumbled over this I would like to know why I’m able to do
something like Java::JavaxSwingJTable.new instead of
Java::JavaxSwing.JTable.new

Shouldn’t that be an error ?

Regards
Roger

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2

On Sat, Jun 5, 2010 at 11:28 AM, Roger G. [email protected] wrote:

Since I just stumbled over this I would like to know why I’m able to do something like Java::JavaxSwingJTable.new instead of Java::JavaxSwing.JTable.new

Since Java packages are lower case and classes are upper case, it is
easy to figure what you need.

For instance, this works

Java::javax.swing.JTable.new

but this doesn’t

Java::javax.Swing.JTable.new (no JRE package by that name)

but this does

Java::Javax.swing.JTable.new (top level package - in JRE it has to
be lower case)

The down side is it takes extra time - up to factor a of 20-30 longer.

The error is the time penalty.

Also, with Java:: for JRE packages, you only need

require ‘java’

you don’t need to include the classes.

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3

What do you mean when you say it’s a factor of 20-30 longer for one or
the other? They should be identical

~/projects/jruby âž” time jruby -rjava -e “p Java::Javax.swing.JTable.new”
#Java::JavaxSwing::JTable:0x1f07597

real 0m2.885s
user 0m1.152s
sys 0m0.167s

~/projects/jruby âž” time jruby -rjava -e “p Java::javax.swing.JTable.new”
#Java::JavaxSwing::JTable:0x54824

real 0m2.638s
user 0m1.118s
sys 0m0.156s

Obviously the one that errors runs much faster because it doesn’t do
anything…

On Sat, Jun 5, 2010 at 2:27 PM, Agile A. [email protected]
wrote:

but this doesn’t
The error is the time penalty.

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4

On Sat, Jun 5, 2010 at 2:36 PM, Roger G. [email protected] wrote:

Since Java packages are lower case and classes are upper case, it is
easy to figure what you need.

Thats true. But I do not understand why something like
Java::javax.swingJTable.new even executes. It seems to be a module. But who
defined it ? Is it automaticaly created by JRuby ? What is it good for ?

Sorry, I have no idea - I just poke it and see what falls out.

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5

Since Java packages are lower case and classes are upper case, it is
easy to figure what you need.

Thats true. But I do not understand why something like
Java::javax.swingJTable.new even executes. It seems to be a module. But
who defined it ? Is it automaticaly created by JRuby ? What is it good
for ?

the down side is it takes extra time - up to factor a of 20-30 longer.

Couldn’t reproduce it either.

Regards
Roger

6

On Sat, Jun 5, 2010 at 3:17 PM, Cinaed S. [email protected]
wrote:

the down side is it takes extra time - up to factor a of 20-30 longer.

Couldn’t reproduce it either.

Hi - not sure if this email was sent from GMail - could’t find the sent
email.

If it was sent I apologize for the noise.

I’m running this in JRuby 1.4 (on CentOS 5 on a netbook.)

Case 1:

require ‘java’

t1 = Time.new

1.upto 1000 do
x=Java::JTable.new
y=Java::JLabel.new
b=Java::JButton.new
a=Java::Class.new
end

puts (Time.now - t1) * 1000

TIME=124

Case 2:

require ‘java’

t1 = Time.new

1.upto 1000 do
x = Java::javax.swing.JTable.new
y = Java::javax.swing.JLabel.new
b = Java::javax.swing.JButton.new
a = x.getClass().name
end

puts (Time.now - t1) * 1000

TIME=3163

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7

Regarding case 1.

You don’t create a JTable here. It’s a module. For more strangeness
try:

require “java”

x=Java::JTable.new

puts x.getRowCount()

Regarding case 2 + 3: They need about the same time to finish here (1.6
seconds)

Regards
Roger

Am 06.06.2010 um 01:11 schrieb Agile A.:

1.upto 1000 do
Bottom line, if you mix Java:: with JRE’s package name, e.g.,
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8

Dang, I forgot Case 3 - which has the same time as Case 1 but only
uses JRE’s package names.

Case 3:

require ‘java’

t1 = Time.new

1.upto 1000 do
x = javax.swing.JTable.new
y = javax.swing.JLabel.new
b = javax.swing.JButton.new
a = x.getClass().name
end

puts (Time.now - t1) * 1000

TIME=124

Bottom line, if you mix Java:: with JRE’s package name, e.g.,
Java::javax.swing.JTable, then you may take a performance hit (but for
a single invocation the time differences appears to be small.)

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