Question

我正在尝试在用户旋转屏幕时恢复RecyclerView数据。这是我的代码：的 __ MESSAGE_Item.java：

public class __MESSAGE_Item implements Serializable {
    private String title, writer, message, index, parent;
    int time, level;

    public __MESSAGE_Item() {
    }

    public __MESSAGE_Item(String title, int time, String writer, String message, String index, String parent, int level) {
        this.title = title;
        this.time = time;
        this.writer = writer;
        this.message = message;
        this.index = index;
        this.parent = parent;
        this.level = level;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public int getTime() {
        return time;
    }

    public void setTime(int time) {
        this.time = time;
    }

    public String getWriter() {
        return writer;
    }

    public void setWriter(String writer) {
        this.writer = writer;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public String getIndex() {
        return index;
    }

    public void setIndex(String index) {
        this.index = index;
    }

    public String getParent()
    {
        return parent;
    }

    public void setParent(String parent)
    {
        this.parent = "בתגובה להודעה " + parent;
    }

    public int getLevel()
    {
        return level;
    }

    public void setLevel(int level)
    {
        this.level = level;
    }
}

MainActivity.java：

private ArrayList<__MESSAGE_Item> MessageList = new ArrayList<__MESSAGE_Item>();
...
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        LVM = (RecyclerView) findViewById(R.id.LVM);
        adapter = new __MESSAGE_ListAdapter(MessageList, getApplicationContext());
        if (savedInstanceState == null) {
            //Call The AsyncTask
            new GetAllMessages().execute();
        }
        .....
}
@Override
    protected void onSaveInstanceState(Bundle savedInstanceState) {
        savedInstanceState.putSerializable("LVMData", MessageList);
        super.onSaveInstanceState(savedInstanceState);
    }

    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        // Always call the superclass so it can restore the view hierarchy
        super.onRestoreInstanceState(savedInstanceState);

        if (savedInstanceState != null) {
            MessageList = (ArrayList<__MESSAGE_Item>) savedInstanceState.getSerializable("LVMData");
            adapter.notifyDataSetChanged();
        }
    }

当我尝试恢复时，数据传递良好，但RecyclerView为空。我做错了什么？

Answer 1

仅当您的活动被杀死时才会调用

onRestoreInstanceState，因此在旋转屏幕时可能不会调用它。您需要在else方法中添加onCreate条件，并在其中添加内容。

Answer 2

@Override
protected void onSaveInstanceState(Bundle savedInstanceState) {
    savedInstanceState.putSerializable("LVMData", MessageList);
    super.onSaveInstanceState(savedInstanceState);
}

这应该是

@Override
protected void onSaveInstanceState(Bundle savedInstanceState) {

    super.onSaveInstanceState(savedInstanceState);
    savedInstanceState.putSerializable("LVMData", MessageList);
}

恢复savedInstanceState不起作用

2 个答案: