为什么在ViewHolder模式中ViewHolder类应该是静态的？

问题描述

我只是想更好地理解我经常用来优化 ListView

I am just trying to have a better understanding of the following pattern I regularly use to optimize ListView

的以下模式我的读物只指出了一个事实，即静态内部类被视为顶级类。与会员类（非静态）相比，这样的事情有什么好处？

My readings only pointed me to the fact that a static inner class is treated as top level class. What is the benefit of such a thing compared to a member class (non static)?

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    Comment comment = getItem(position);
    ViewHolder holder;
    if (convertView == null){
        holder = new ViewHolder();
        convertView = LayoutInflater.from(context).inflate(R.layout.mylayout, null);
        holder.nickname = (TextView) ((ViewGroup) convertView).findViewById(R.id.nickname);
        convertView.setTag(holder);
    }else{
        holder = (ViewHolder) convertView.getTag();
    }

    holder.nickname.setText(comment.getMember_nickname());
    CharSequence
    return convertView;
}

public static class ViewHolder{
    TextView nickname;
}

推荐答案

使用静态内在的一个好处class，是可以从静态方法访问内部类，而不需要外部类的实例。

One benefit of using static inner class, is that the inner class can be accessed from static methods, without having an instance of the outer class.

如果内部类是非静态的：

If the inner class non-static:

class MyOuter {
    private int x = 7;
    public void makeInner() {
        MyInner in = new MyInner();
        in.seeOuter();
    }
    class MyInner {
        public void seeOuter() {
            System.out.println("Outer x is " + x);
        }
    }
}

public static void main(String[] args) {
    MyOuter mo = new MyOuter();
    MyOuter.MyInner inner = mo.new MyInner();
    inner.seeOuter();
}

如果内部类是静态的：

class BigOuter {
    static class Nest {void go() { System.out.println("hi"); } }
}

class Broom {
    static class B2 {void goB2() { System.out.println("hi 2"); } }
    public static void main(String[] args) {
        BigOuter.Nest n = new BigOuter.Nest();
        n.go();
        B2 b2 = new B2();
        b2.goB2();
    }
}

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