Question

我正在尝试将元素添加到ArrayList<Movements>movement作为构建器模式的一部分。

Movement类包含int movementId和String movementName，我希望用户使用构建器模式将这些添加到合成中。

我正在努力实施，见下文：

    public static class CompositionBuilder{
        private final String compositionId;
        private List<Movements> movement = new ArrayList<Movements>();
        private final String compositionName;
        private final String composerName;

    public CompositionBuilder(String compositionId, String compositionName, String composerName){
        this.compositionId = compositionId;
        this.compositionName = compositionName;
        this.composerName = composerName;
    }

    //this part is where I am struggling. I don't know how to populate the ArrayList
    public CompositionBuilder movement(Movements...movement){       
        for (Movements i : movement){ 
            this.movement.add(i);
        }
        return this;
    }

    public Composition build(){
        return new Composition(this);
    }
}

我希望能够使用

构建合成

public class CompositionBuilderTest {

    public static void main (String[] args){        

        Composition composition1 = new Composition.CompositionBuilder("1", "CompositionOne", "John Doe")
                                                                .movement()//enter movement values here
                                                                .build();
        System.out.println(composition1);
    }
}

组合构造函数：

    private Composition(CompositionBuilder builder){
        this.compositionId = builder.compositionId;
        this.movement = builder.movement;
        this.compositionName = builder.compositionName;
        this.composerName = builder.composerName;
}

Answer 1

使用CompositionBuilder创建Movement实例将违反SRP（您需要修改构建器中movement方法的签名）。相反，您应该将Movement的实例传递给movement(Movement...movements)方法，调用构造函数或工厂

Composition composition1 = new Composition.CompositionBuilder("1", "CompositionOne", "John Doe")
                                                            .movement(Movement.newInstance(id, name), Movement.newInstance(id2, name2))
                                                            .build();

使用Java中的构建器模式向ArrayList添加元素

1 个答案: