Question

我们想在另一个类中调用列表视图'm_vwList'，这样当按下签出按钮（在另一个类中）时，列表将从快速订单类中清除。

有人可以告诉如何在另一个类中调用列表视图，然后在单击按钮后清除它。我们知道按钮功能，但不知道如何清除列表

    package com.zing.basket;

    import android.app.Fragment;
    import android.os.Bundle;
    import android.view.KeyEvent;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ArrayAdapter;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.ListView;

    /**
      * Created by Student on 18/03/2016.
      */
     public class QuickOrder  extends android.support.v4.app.Fragment implements View.OnClickListener, View.OnKeyListener {

    private EditText m_vwEditText;
    private Button m_vwButton;
    private ListView m_vwList;
    private ArrayAdapter<String> m_adapter;

    View myFragmentView;


    @Override
    public void onCreate(Bundle savedInstanceState)
    {

        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {


        myFragmentView = inflater.inflate(R.layout.fragment_quickorder, container, false);


        m_vwEditText = (EditText) myFragmentView.findViewById(R.id.editText);
        m_vwButton = (Button) myFragmentView.findViewById(R.id.button);
        m_vwList = (ListView) myFragmentView.findViewById(R.id.list);

        m_adapter = new ArrayAdapter<String>(getActivity(), R.layout.textview);
        String[] listItems = getResources().getStringArray(R.array.listitems);
        for (String item : listItems) {
            m_adapter.add(item);
        }
        m_vwList.setAdapter(m_adapter);

        m_vwButton.setOnClickListener(this);
        m_vwEditText.setOnKeyListener(this);


        return myFragmentView;
    }



    /** Called when the Button is clicked */

    public void onClick(View v) {
        String item = m_vwEditText.getText().toString();
        m_vwEditText.setText("");
        if (!item.equals("")) m_adapter.add(item);
    }

    /** Called whena key is pressed while the EditText view has focus */

    public boolean onKey(View v, int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER || keyCode == KeyEvent.KEYCODE_ENTER) {
            if (event.getAction() == KeyEvent.ACTION_UP) {
                String item = m_vwEditText.getText().toString();
                m_vwEditText.setText("");
                if (!item.equals("")) m_adapter.add(item);
            }
            return true;
        }
        return false;
    }



}

Answer 1

要调用其他类的ListView，您需要获取该类的实例并检查它是否为null。更多关注：

  if (MainActivity.getInstance() != null) {
     MainActivity.getInstance().mDrawerList.invalidateViews();
     }

如何在另一个类中调用列表视图，然后清除它

1 个答案: