android - ListView 未使用 notifydatasetchanged() 调用进行更新

Question

这是我的代码

listview =(ListView) findViewById(R.id.lv1);


    ArrayList<SClass> Monday = new ArrayList<SClass>();

    SClass s1=new SClass();
    s1.sName="samp";
    s1.salary=1000;
    Monday.add(s1);
    temp=Monday;
    adapter = new CustomAdap(this, temp);
    listview.setAdapter(adapter);

上面的代码工作正常。但是当我把我的代码改成这个时

    listview =(ListView) findViewById(R.id.lv1);


    adapter = new CustomAdap(this, temp);

    SClass s1=new SClass();
    s1.sName="samp";
    s1.salary=1000;
    Monday.add(s1);
    temp=Monday;

    listview.setAdapter(adapter);
    adapter.notifyDataSetChanged();

Listview 不显示任何内容。问题是什么？

Answer 1

看起来您正在更改用于初始化适配器的集合。我会以这种方式更改您的代码:

// initial setup
listview =(ListView) findViewById(R.id.lv1);
ArrayList<SClass> Monday = new ArrayList<SClass>();
adapter = new CustomAdap(this, Monday);
listview.setAdapter(adapter);

// change your model Monday here, since it is what the adapter is observing
SClass s1=new SubjectClass();
s1.sName="samp";
s1.salary=1000;
Monday.add(s1);

// notify the list that the underlying model has changed
adapter.notifyDataSetChanged();

请注意，如果您的 CustomAdap 是 ArrayAdapter 的子类，您也可以这样做

// change your array adapter here
SClass s1=new SubjectClass();
s1.sName="samp";
s1.salary=1000;
adapter.add(s1);

// notify the list that the underlying model has changed
adapter.notifyDataSetChanged();

编辑:感谢您的评论，我更了解您现在想做什么。您可能希望让适配器用您的不同 ArrayLists 替换它的内容。我会让您的 CustomAdap 成为 ArrayAdapter 的子类。

然后你可以这样使用它:

// replace the array adapters contents with the ArrayList corresponding to the day
adapter.clear();
adapter.addAll(MONDAY);

// notify the list that the underlying model has changed
adapter.notifyDataSetChanged();