CODEWITHSUNDEEP
genericsjavafx-2
Peter Hull
Peter Hull

Reputation: 7067

JavaFX builders/Java Generics

I want to re-use a Builder instance to create several controls but I'm getting compile errors which I don't understand. I think they're caused by me not understanding generics properly. Can anyone help?

ButtonBuilder builder = ButtonBuilder.create().minHeight(40.0).minWidth(40.0);
Button button1 = builder.onAction(clickHandler).build(); // Error
Button button2 = ButtonBuilder.create().minHeight(40.0).minWidth(40.0).onAction(clickHandler).build(); //OK

where clickHandler is a EventHandler<ActionEvent>

The error I get is 

error: cannot find symbol
    Button button1 = builder.onAction(clickHandler).build();
                                                   ^
symbol:   method build()
location: class ButtonBaseBuilder

ButtonBaseBuilder implements Builder so it should have a build() method, shouldn't it? Also if I run everything together (as in button2) it is OK.

This is on JDK 7.0u4 and JavaFX SDK 2.1

Thanks in advance, Pete

Upvotes: 2

Views: 813

Answers (2)

Sergey Grinev
Sergey Grinev

Reputation: 34508

You need to pass ButtonBuilder generic parameter to use builders that way:

    ButtonBuilder<? extends ButtonBuilder> builder =
                     ButtonBuilder.create().minHeight(40.0).minWidth(40.0);
    Button button1 = builder.onAction(clickHandler).build();

Upvotes: 2

assylias
assylias

Reputation: 328639

ButtonBaseBuilder does not have a build method. ButtonBuilder, which extends ButtonBaseBuilder, has one because it implements Builder<Button>.

This should work:

Button button1 = ((ButtonBuilder) builder.onAction(clickHandler)).build();

Upvotes: 2

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