java - 用于不止一种类类型的 ArrayAdapter

Question

拥有可以处理多种对象类型的数组适配器的最佳实践是什么？

Adapter extends ArrayAdapter<?>

我有 3 种类型的类(class) A.class , B.class , C.class适配器中的逻辑是相同的。

public class Adapter extends ArrayAdapter<A,B,C ?> {

private int viewResourceId;
private LayoutInflater inflater;
private ArrayList<A,B,C ?> list;

public Adapter(Context context, int viewResourceId, ArrayList<A,B,C ?> list) {
    super(context, viewResourceId, list);
    this.viewResourceId = viewResourceId;
    this.list = list;

    inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

@Override
public int getCount() {
    return list.size();
}

@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
    Holder holder;

    if (arg1 == null || arg1.getTag() == null) {
        holder = new Holder();

        arg1 = inflater.inflate(viewResourceId, null);
        arg1.setTag(holder);

        holder.textView = (TextView) arg1.findViewById(R.id.textView);
    } else {
        holder = (Holder) arg1.getTag();
    }

    // A,B,C
    holder.textView.setText(list.get(arg0).getName());

    return arg1;
}

static class Holder {
    TextView textView;
}

}

现在我为每个类类型提供了 3 个不同的适配器，并将其设置为列表

listView.setAdapter(new Adapter(this, R.layout.row_item, list<A,B,C ?>))

Answer 1

你可以让它通用 -

    public class Adapter<T> extends ArrayAdapter<T> {

    private int viewResourceId;
    private LayoutInflater inflater;
    private ArrayList<T> list;

    public Adapter(Context context, int viewResourceId, ArrayList<T> list) {
        super(context, viewResourceId, list);
        this.viewResourceId = viewResourceId;
        this.list = list;

        inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public View getView(int arg0, View arg1, ViewGroup arg2) {
        Holder holder;

        if (arg1 == null || arg1.getTag() == null) {
            holder = new Holder();

            arg1 = inflater.inflate(viewResourceId, null);
            arg1.setTag(holder);

            holder.textView = (TextView) arg1.findViewById(R.id.txtUse);
        } else {
            holder = (Holder) arg1.getTag();
        }

        // A,B,C
        if(list.get(arg0)  instanceof A){
            //User A's property to set TextView text
        } else if(list.get(arg0) instanceof B){
            //User B's property to set TextView text
        } else if(list.get(arg0) instanceof C){
            //User C's property to set TextView text
        }

        return arg1;
    }

    static class Holder {
        TextView textView;
    }
}