Chained invocation in Java 7?

Question

I was just reading a Java 7 preview presentation (pdf) and there was a slide on Chained Invocation. Here is the example used in the slide: ``` // Construction with setters DrinkBuilder margarita = new DrinkBuilder(); margarita.add("tequila"); margarita.add("orange liqueur"); margarita.add("lime juice"); margarita.withRocks(); margarita.withSalt(); Drink drink = margarita.drink(); // Construction with chained invocation Drink margarita = new DrinkBuilder() .add("tequila") .add("orange liqueur") .add("lime juice") .withRocks() .withSalt() .drink(); ``` And I have mixed feelings about this. One shouldn't chain too many method invocations into one statement. On the other hand, writing `margarita.this()` and `margarita.that()` isn't too convenient either. Now, I am coming to Java from Delphi world. And in Delphi there is the `with` language construct. This is cherished by a few and loathed by many (or is it the other way around?). I find `with` to be more elegant than the idea of chained i…

Accepted Answer

the with statement can be translated in Java using anonymous classes with initializer:

```
Drink margarita = new DrinkBuilder() {{
    add(“tequila”);
    add(“orange liqueur”);
    add(“lime juice”);
    withRocks();
    withSalt();
}}.drink();
```

the downsides of using this idiom are well documented here.

Chained Invocation is an alias for Method Chaining. That is well known idiom and works with any version of Java:

```
class Chained {

public Chained withFoo() { 
        // ...
        return this;
    }

public Chained withBar() { 
        // ...
        return this;
    }
}    
```

a proposal for JDK 7 is allowing of chaining method also for void return type:

```
class ChainedJava7 {

public void withFoo() { 
        // ...
    }

public void withBar() { 
        // ...
    }
}    
```

Chained invocation in Java 7?

Solution

Problem

Related problems