```ruby
require 'java'

class ASTTreeViewBuilder
  include JRubyFX
  attr_accessor :tree_view
  
  def initialize(tree_view)
    @tree_view = tree_view
  end
  
  def build_tree_item(node)
    node_information = node.respond_to?(:name) ? ":#{node.name}" : ""
    node_string = "#{node.node_name}#{node_information} #{node.position.start_line}"
    TreeItem.new(node_string)
  end
  
  def build_view(node, parent_node=nil)
    if parent_node.nil?
      # root node
      parent_node = @tree_view.root = build_tree_item(node)
    else
      # non root node
      node_tree_item = build_tree_item(node)
      parent_node.children << node_tree_item
      parent_node = node_tree_item
    end
    
    node.child_nodes.each { |child| build_view(child, parent_node) }
  end
end

if __FILE__ == $0
  require 'jruby'
  root = JRuby.parse("def foo; 42; end; foo")
  builder = ASTTreeViewBuilder.new(nil)
  builder.build_view(root)
end
```

Use inner method to remove conditional
user
```ruby
require 'java'

class ASTTreeViewBuilder
  include JRubyFX
  attr_accessor :tree_view
  
  def initialize(tree_view)
    @tree_view = tree_view
  end
  
  def build_tree_item(node)
    node_information = node.respond_to?(:name) ? ":#{node.name}" : ""
    node_string = "#{node.node_name}#{node_information} #{node.position.start_line}"
    TreeItem.new(node_string)
  end

  def build_view(root)
    @tree_view.root = build_tree_item(root)
    root.child_nodes.each { |child| build_view_inner(child, @tree_view.root) }
  end
  
  def build_view_inner(node, parent_item)
    tree_item = build_tree_item(node)
    parent_item.children << tree_item
    node.child_nodes.each { |child| build_view_inner(child, tree_item) }
  end
  private :build_view_inner
end

if __FILE__ == $0
  require 'jruby'
  root = JRuby.parse("def foo; 42; end; foo")
  builder = ASTTreeViewBuilder.new(nil)
  builder.build_view(root)
end
```
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