问题

Question

我有ListView，如下图所示

每个白框都是一个单独的ListView行。每个ListView行的右上角都有一个Button。

我想要什么

我正在尝试在每行OnClickListener上设置Button。只要单击此Button，我就想删除该行。

每个ListView行中的数据来自Firebase数据库。因此，只要在Button的任意行中点击了交叉ListView，我就会获得Timestamp的值，然后将此Timestamp作为参数传递到单独的搜索方法中在此Timestamp的数据库中。 <{1}}数据库中以Firebase为其子项的任何键都将被删除。

用于删除Timestamp行数据的方法工作正常，因为它删除了与此方法中传递的ListView相关联的数据作为参数。

问题

问题是，当点击任何Timestamp上的按钮时，我得到的Timestamp值是错误的。例如，在上图中，如果我点击ListView ListView Timestamp行的第27-01-2018 05-31-22AM行，而不是Timestamp，我会获得Timestamp ListView的最后一行，因此删除了错误的数据。

以下是相关代码：

onClick（）方法

@Override
public void onClick(View view) {
        //get the parent view i.e. listview row on which delete button is clicked
        ConstraintLayout listviewRow = (ConstraintLayout) btnDeleteMsg.getParent();

        //get the textview containing receiver username from the view on which delete button is clicked
        TextView textviewReceiver = listviewRow.findViewById(R.id.outbox_msgReceiverUsername);

        //get the textview containing timestamp value from the view on which delete button is clicked
        TextView textTimestamp = listviewRow.findViewById(R.id.outbox_msgSentTime);

        //get the values of message receiver username and timestamp
        //timestamp value will be used to determine which message to delete
        //from database
        String receiverUsername = textviewReceiver.getText().toString();
        String timestamp = textTimestamp.getText().toString();

        //call delSentMsg() method in SentMessages Fragment using SentMessages Fragment
        //instance passed in the constructor of this class
        sentMsgsFragment.deleteSentMsg(receiverUsername, timestamp);
}

ListView行布局

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:padding="15dp"
    android:background="#fff">

    <Button
        android:id="@+id/btn_deleteMsg_SMF"
        android:layout_width="17dp"
        android:layout_height="17dp"
        android:background="@drawable/cross_image"
        app:layout_constraintRight_toRightOf="parent" />

    <TextView
        android:id="@+id/outbox_msgText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="#000"
        android:textSize="22sp"
        android:paddingTop="10dp"
        app:layout_constraintTop_toBottomOf="@id/btn_deleteMsg_SMF"/>

    <TextView
        android:id="@+id/outbox_msgReceiverLabel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/to_text_label"
        android:textColor="#000"
        android:textSize="18sp"
        app:layout_constraintTop_toBottomOf="@id/outbox_msgText"
        app:layout_constraintLeft_toLeftOf="parent"
        android:paddingTop="10dp"/>

    <TextView
        android:id="@+id/outbox_msgReceiverUsername"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        app:layout_constraintLeft_toRightOf="@id/outbox_msgReceiverLabel"
        android:layout_marginLeft="10dp"
        app:layout_constraintTop_toBottomOf="@id/outbox_msgText"
        android:paddingTop="10dp"/>

    <TextView
        android:id="@+id/outbox_msgDateLabel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/sent_on_label"
        android:textColor="#000"
        android:textSize="18sp"
        app:layout_constraintTop_toBottomOf="@id/outbox_msgReceiverLabel"
        app:layout_constraintLeft_toLeftOf="parent"
        android:paddingTop="10dp"/>

    <TextView
        android:id="@+id/outbox_msgSentTime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="16sp"
        app:layout_constraintLeft_toRightOf="@id/outbox_msgDateLabel"
        app:layout_constraintTop_toBottomOf="@id/outbox_msgReceiverLabel"
        android:layout_marginLeft="10dp"
        app:layout_constraintBaseline_toBaselineOf="@id/outbox_msgDateLabel"
        android:paddingTop="10dp"/>

</android.support.constraint.ConstraintLayout>

ListView适配器类

public class CustomOutboxListAdapter extends BaseAdapter implements View.OnClickListener{

    private ArrayList<SentMessageTemplate> sentMsgsList;
    private Context context;
    private Button btnDeleteMsg;
    private SentMessages sentMsgsFragment;

    public CustomOutboxListAdapter(ArrayList<SentMessageTemplate> list, Context cont, SentMessages sm){
        this.sentMsgsList = list;
        this.context = cont;
        this.sentMsgsFragment = sm;
    }

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

    @Override
    public Object getItem(int position) {
        return this.sentMsgsList.get(position);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;

        if(convertView == null){
            LayoutInflater inf = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inf.inflate(R.layout.listview_outbox_messages_row, null);

            //private inner class used to minimize the calls to "findViewById" method
            holder = new ViewHolder();
            holder.datetimeText = convertView.findViewById(R.id.outbox_msgSentTime);
            holder.messageText = convertView.findViewById(R.id.outbox_msgText);
            holder.receiverUsernameText = convertView.findViewById(R.id.outbox_msgReceiverUsername);

            convertView.setTag(holder);

            //click listener for delete button
            btnDeleteMsg = convertView.findViewById(R.id.btn_deleteMsg_SMF);
            btnDeleteMsg.setOnClickListener(this);
        }
        else {
            holder = (ViewHolder)convertView.getTag();
        }

        SentMessageTemplate stu = sentMsgsList.get(position);
        holder.datetimeText.setText(stu.getTimestamp());
        holder.messageText.setText(stu.getMessageContent());
        holder.receiverUsernameText.setText(stu.getMsgReceiver());

        return convertView;
    }

    @Override
    public void onClick(View view) {
        //get the parent view i.e. listview row on which delete button is clicked
        ConstraintLayout listviewRow = (ConstraintLayout) btnDeleteMsg.getParent();
        //get the textview containing receiver username from the view on which delete button is clicked
        TextView textviewReceiver = listviewRow.findViewById(R.id.outbox_msgReceiverUsername);
        //get the textview containing timestamp value from the view on which delete button is clicked
        TextView textTimestamp = listviewRow.findViewById(R.id.outbox_msgSentTime);
        //get the values of message receiver username and timestamp
        //timestamp value will be used to determine which message to delete
        //from database
        String receiverUsername = textviewReceiver.getText().toString();
        String timestamp = textTimestamp.getText().toString();
        //call delSentMsg() method in SentMessages Fragment using SentMessages Fragment
        //instance passed in the constructor of this class
        sentMsgsFragment.deleteSentMsg(receiverUsername, timestamp);
    }

    private static class ViewHolder{
        public TextView datetimeText;
        public TextView messageText;
        public TextView receiverUsernameText;
    }
}

问题

我认为问题是我无法正确获取点击了十字按钮的ListView行。如何在单击按钮时确定ListView行？

Answer 1

尝试对CustomOutboxListAdapter课程进行这些更改。

在CustomOutboxListAdapter中未执行View.OnClickListener。从：

更改它的类声明

public class CustomOutboxListAdapter extends BaseAdapter implements View.OnClickListener{

为：

public class CustomOutboxListAdapter extends BaseAdapter {

删除里面的onClick方法：

@Override
public void onClick(View view) {

将public View getView(int position, View convertView, ViewGroup parent)替换为：

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder = null;

    if(convertView == null){
        LayoutInflater inf = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inf.inflate(R.layout.listview_outbox_messages_row, null);

        //private inner class used to minimize the calls to "findViewById" method
        holder = new ViewHolder();
        holder.datetimeText = convertView.findViewById(R.id.outbox_msgSentTime);
        holder.messageText = convertView.findViewById(R.id.outbox_msgText);
        holder.receiverUsernameText = convertView.findViewById(R.id.outbox_msgReceiverUsername);

        convertView.setTag(holder);
    }
    else {
        holder = (ViewHolder)convertView.getTag();
    }

    SentMessageTemplate stu = sentMsgsList.get(position);
    holder.datetimeText.setText(stu.getTimestamp());
    holder.messageText.setText(stu.getMessageContent());
    holder.receiverUsernameText.setText(stu.getMsgReceiver());


    // use local variable so it is always referenced correctly
    Button deleteBtn = convertView.findViewById(R.id.btn_deleteMsg_SMF);
    // Cache row position inside the button using `setTag`
    deleteBtn.setTag(position); 

    // Attach the click event handler
    deleteBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            int position = (Integer) view.getTag();

            // Access the row position here to get the correct data item
            SentMessageTemplate sentMessageTemplate = getItem(position);

            String receiverUsername = sentMessageTemplate.getTimestamp();
            String timestamp = sentMessageTemplate.getMsgReceiver();

            sentMsgsFragment.deleteSentMsg(receiverUsername, timestamp);
        }
    });

    return convertView;
}

只需删除不再使用的成员变量private Button btnDeleteMsg;。

对于getItemId(int i)实施，我认为应该是这样的：

@Override
public long getItemId( int position ) {
    return this.sentMsgsList.get(position).getId();
}

然后在SentMessageTemplate类中，它应该实现：

public int getId() {
    // return unique ID for object
    ....
}

Answer 2

错误是只有当适配器为> react-app-rewired build sh: 1: react-app-rewired: not found npm ERR! file sh npm ERR! code ELIFECYCLE npm ERR! errno ENOENT npm ERR! syscall spawn npm ERR! client@0.1.0 build: `react-app-rewired build` npm ERR! spawn ENOENT npm ERR! npm ERR! Failed at the client@0.1.0 build script. npm ERR! This is probably not a problem with npm. There is likely additional logging output above. npm ERR! A complete log of this run can be found in: npm ERR! /app/.npm/_logs/2018-01-27T03_26_58_947Z-debug.log npm ERR! code ELIFECYCLE npm ERR! errno 1 npm ERR! infinity2o_server@1.0.0 heroku-postbuild: `NPM_CONFIG_PRODUCTION=false npm install --prefix client && npm run build --prefix client` npm ERR! Exit status 1 npm ERR! npm ERR! Failed at the infinity2o_server@1.0.0 heroku-postbuild script.创建新视图时才调用btnDeleteMsg.setOnClickListener(this);。它仅在应用程序启动时发生，在ListView重用视图之后并且不调用ListView。因此，要解决您的问题，请将此行移至btnDeleteMsg.setOnClickListener(this);

下方

如下所示

holder.receiverUsernameText.setText(stu.getMsgReceiver());

Answer 3

我不确定我完全理解这个问题但是：

您可以通过在视图上调用setId来设置ID。为您的行提供唯一的数字。然后使用onClick函数中的getId检索ID，以了解单击了哪一行，以便删除它。这比使用Timestamp更好，因为它们可能巧合地重叠，而你可以确保ID都是不同的。

在Listview行布局中的按钮上设置单击侦听器

我想要什么

问题

问题

3 个答案: