Question

当我按下后退按钮时，此ShoppingActivity会被破坏，当我再次访问该活动时，我发现我的回收者视图项目被替换了两次。我该如何解决这个问题？

ShoppingActivity.java 当我再次按下并再次访问该活动时，这里写的所有代码和volley类也被调用，我发现我的回收器视图项被替换了 @覆盖 protected void onCreate（Bundle savedInstanceState）{ super.onCreate（savedInstanceState）; 的setContentView（R.layout.activity_shopping）;

public class Animal {

private Room currentRoom;
private String name;

public Animal() {
}

public Animal(String name) {
setName(name);
}

public void setName(String name) {
this.name = name;
}

public String toString() {
return "\t" + name;
}

public void look() {
    System.out.println(name + " is currently in " + getCurrentRoom());
//getCurrentRoom().toString();
}

public Room getCurrentRoom() {
return this.currentRoom;
}

public void setCurrentRoom(Room currentRoom) {
this.currentRoom = currentRoom;
}
}

这是我的DetailsViewActivity.java

    recyclerView = (RecyclerView) findViewById(R.id.rv_recycler_view);
    layoutManager = new LinearLayoutManager(this);

    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(layoutManager);

    btn_sort_name = (Button) findViewById(R.id.btn_name);
    btn_sort_price = (Button) findViewById(R.id.btn_price);

    tv_total_products = (TextView) findViewById(R.id.totalproduct);
    tv_apihits = (TextView) findViewById(R.id.apihits);

    tv_total_products.setText(null);

    if(savedInstanceState==null){
    final JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Request.Method.GET,
            BaseUrl,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {
                    int index = 0;
                    arrayList.clear();
                    while (index < response.length()) {
                        try {
                            JSONObject jsonObject = response.getJSONObject(index);
                            arrayList.add(new Items(jsonObject.getString("name"),
                                    jsonObject.getString("description"),
                                    jsonObject.getString("category"),
                                    jsonObject.getDouble("price"),
                                    jsonObject.getInt("quantity"),
                                    jsonObject.getString("shipping"),
                                    jsonObject.getString("location"),
                                    jsonObject.getString("color"),
                                    jsonObject.getString("link")));
                            da = jsonObject.getString("name");
                            Log.d(TAG, da);
                            index++;
                            total_products = index;
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }

                    }

                    recyclerViewAdapter = new RecyclerViewAdapter(arrayList, ShoppingActivity.this);
                    recyclerView.setAdapter(recyclerViewAdapter);
                    tv_total_products.append(String.valueOf(total_products));

                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.d(TAG, "Error");
                }
            });

    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(jsonArrayRequest);
}

    recyclerView.addOnItemTouchListener(new RecyclerViewAdapter.ViewItemClick(getApplicationContext(), recyclerView,
            new RecyclerViewAdapter.ItemClickListener() {
                @Override
                public void clickedItem(View view, int position) {

                    name = arrayList.get(position).getName();
                    description = arrayList.get(position).getDescription();
                    category = arrayList.get(position).getCategory();
                    shipping = arrayList.get(position).getShipping();
                    location = arrayList.get(position).getLocation();
                    color = arrayList.get(position).getColor();
                    link = arrayList.get(position).getLink();
                    price = arrayList.get(position).getPrice();
                    quantity = arrayList.get(position).getQuantity();
                    DataParcel dataParcel = new DataParcel(name, description, category, shipping, location, color, link, price, quantity);

                    Intent intent = new Intent(ShoppingActivity.this, DetailsViewActivity.class);
                    intent.putExtra("data", dataParcel);
                    startActivity(intent);

                }
            }));

}

@Override
public void onBackPressed() {

    super.onBackPressed();
    finish();
}

Answer 1

问题在于您的活动的生命周期，您可以检查从另一个活动返回时第一个活动的实例是否仍然存在。为了快速修复，您可以在填充数据之前清除您的arraylist，这将清除从其他活动返回时以前添加的数据，您可以将其作为

var mainUIView: UIView!

var scrollView: UIScrollView!
var arrayOfView: [UIView]?


override init(frame: CGRect) {
    super.init(frame: frame)

    self.setupView()
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

fileprivate func setupView() {
    // MainUiView
    self.mainUIView = UIView(frame: self.frame)
    self.addSubview(mainUIView)

    // ScrollView
    self.scrollView = UIScrollView(frame: self.frame)
    self.scrollView.delegate = self
    self.addSubview(self.scrollView)
}

func reloadViews(postArray:[Post]?) {
    if let postArray = postArray {
        print("UIFreeView::reloadVIew.postArraySize = \(postArray.count)")
        let size: CGFloat = 80.0
        let margin: CGFloat = 20.0
        scrollView.contentSize.width = (size * CGFloat(postArray.count))+(margin*CGFloat(postArray.count))
        scrollView.contentSize.height = (size * CGFloat(postArray.count))+(margin*CGFloat(postArray.count))

        for item in postArray {
            let view = buildPostView(item)

            self.scrollView.addSubview(view)
        }
    }

}

fileprivate func buildPostView(_ item:Post) -> UIView {
    // Const
    let size: CGFloat = 80.0
    let margin: CGFloat = 5.0

    // Var
    let view = UIView()
    let textView = UITextView()
    let backgroundImageView = UIImageView()
    // Setup view

    let x = CGFloat(UInt64.random(lower: UInt64(0), upper: UInt64(self.scrollView.contentSize.width)))
    let y = CGFloat(UInt64.random(lower: UInt64(0), upper: UInt64(self.scrollView.contentSize.height)))


    view.frame = CGRect(x: x,
                        y: y,
                        width: size,
                        height: size)

    // Setup background view
    backgroundImageView.frame = CGRect(x: 0,
                                       y: 0,
                                       width: view.frame.size.width,
                                       height: view.frame.size.height)
    var bgName = ""
    if (item.isFromCurrentUser) {
        bgName = "post-it-orange"
    } else {
        bgName = "post-it-white"
    }
    backgroundImageView.contentMode = .scaleAspectFit
    backgroundImageView.image = UIImage(named: bgName)
    view.addSubview(backgroundImageView)

    // Setup text view 
    textView.frame = CGRect(x: margin,
                            y: margin,
                            width: view.frame.size.width - margin*2,
                            height: view.frame.size.height - margin*2)
    textView.backgroundColor = UIColor.clear
    textView.text = item.content
    textView.isEditable = false
    textView.isSelectable = false
    textView.isUserInteractionEnabled = false

    view.addSubview(textView)

    let gestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
    view.addGestureRecognizer(gestureRecognizer)

    return view
}

func viewForZooming(in scrollView: UIScrollView) -> UIView? {
    return self.scrollView
}

func handlePan(_ gestureRecognizer: UIPanGestureRecognizer) {
    if gestureRecognizer.state == .began || gestureRecognizer.state == .changed {

        let translation = gestureRecognizer.translation(in: self.scrollView)
        // note: 'view' is optional and need to be unwrapped
        gestureRecognizer.view!.center = CGPoint(x: gestureRecognizer.view!.center.x + translation.x, y: gestureRecognizer.view!.center.y + translation.y)
        gestureRecognizer.setTranslation(CGPoint.zero, in: self.scrollView)
    }
}

/*
// Only override draw() if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func draw(_ rect: CGRect) {
    // Drawing code
}
*/

前

arrayList.clear();

在响应块上。但这只是一个快速修复，而不是实际的解决方案，所以更好的想法是检查类的实例。

Recycler Item视图未正确显示数据

1 个答案: