Java中初始化代码的抽象与重构：避免构造器调用抽象方法陷阱

// 示例1: 原始的重复初始化代码
public class LoadElement {
    LoadingElementBinding binding;

    public LoadElement(ViewGroup parent) {
        binding = LoadingElementBinding.inflate(
                       LayoutInflater.from(parent.getContext()),
                       parent,
                       false);
        binding.setLifecycleOwner(ViewTreeLifecycleOwner.get(parent));
    }

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

public class ErrorElement {
    ErrorElementBinding binding;

    public ErrorElement(ViewGroup parent) {
        binding = ErrorElementBinding.inflate(
                       LayoutInflater.from(parent.getContext()),
                       parent,
                       false);
        binding.setLifecycleOwner(ViewTreeLifecycleOwner.get(parent));
    }

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

// 示例2: 尝试使用抽象方法在构造器中初始化 (错误示例)
public abstract class BindingElement <T extends ViewDataBinding>{
    T binding; // 声明为protected可能更合适，以便子类访问

    public BindingElement (ViewGroup parent) {
        // 在构造器中调用抽象方法 createBinding
        binding = createBinding(LayoutInflater.from(parent.getContext()), parent);
        binding.setLifecycleOwner(ViewTreeLifecycleOwner.get(parent));
    }

    // 抽象方法，由子类实现具体的绑定创建逻辑
    abstract T createBinding(LayoutInflater inflater, ViewGroup parent);

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

public class LoadElement extends BindingElement<LoadingElementBinding>{
    public LoadElement(ViewGroup parent) {
        super(parent);
    }

    @Override
    LoadingElementBinding createBinding(LayoutInflater inflater, ViewGroup parent){
       return LoadingElementBinding.inflate(inflater, parent, false);
    }
}

public class ErrorElement extends BindingElement<ErrorElementBinding>{
    public ErrorElement(ViewGroup parent) {
        super(parent);
    }

    @Override
    ErrorElementBinding createBinding(LayoutInflater inflater, ViewGroup parent){
       return ErrorElementBinding.inflate(inflater, parent, false);
    }
}

// 示例3.1: 定义函数式接口
@FunctionalInterface
public interface BindingCreator<T extends ViewDataBinding>{
    /**
     * 创建并返回一个ViewDataBinding实例。
     * @param inflater 用于膨胀布局的LayoutInflater。
     * @param parent 绑定的父视图组。
     * @param attachToParent 是否将布局附加到父视图组。
     * @return 创建的ViewDataBinding实例。
     */
    T createBinding(LayoutInflater inflater, ViewGroup parent, boolean attachToParent);
}

// 示例3.2: 修改抽象基类，接受BindingCreator
public abstract class BindingElement <T extends ViewDataBinding>{
    protected T binding; // 建议将binding声明为protected，便于子类直接访问

    public BindingElement(ViewGroup parent, BindingCreator<T> bindingCreator){
        // 通过传入的bindingCreator来创建绑定实例
        binding = bindingCreator.createBinding(
                       LayoutInflater.from(parent.getContext()),
                       parent,
                       false); // 这里的false通常是 inflate 方法的第三个参数
        binding.setLifecycleOwner(ViewTreeLifecycleOwner.get(parent));
    }

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

// 示例3.3: 子类使用方法引用实现
public class LoadElement extends BindingElement<LoadingElementBinding>{
    public LoadElement(ViewGroup parent) {
        // 将LoadingElementBinding::inflate 方法引用作为BindingCreator传递给父类
        super(parent, LoadingElementBinding::inflate);
    }
    // 其他LoadElement特有的方法
}

public class ErrorElement extends BindingElement<ErrorElementBinding>{
    public ErrorElement(ViewGroup parent) {
        // 将ErrorElementBinding::inflate 方法引用作为BindingCreator传递给父类
        super(parent, ErrorElementBinding::inflate);
    }
    // 其他ErrorElement特有的方法
}