我正在尝试设置自定义适配器，以便在列表视图上使用演示聊天应用程序向用户显示消息，但在我的自定义列表适配器的getView方法中接收错误。
错误在线：
holder.message.setText("lol");
自定义适配器的getView（）中可能出现的错误是什么？感谢任何提示和帮助提前。
我的自定义适配器：
import java.util.ArrayList;
import android.content.Context;
import android.support.v4.view.ViewPager.LayoutParams;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class ChattingAdapter extends BaseAdapter{
private Context mContext;
private ArrayList<ChatMessage> mMessages;
public ChattingAdapter(Context context, ArrayList<ChatMessage> messages) {
super();
this.mContext = context;
this.mMessages = messages;
}
@Override
public int getCount() {
return mMessages.size();
}
@Override
public Object getItem(int position) {
return mMessages.get(position);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ChatMessage message = (ChatMessage) this.getItem(position);
ViewHolder holder;
if(convertView == null)
{
holder = new ViewHolder();
convertView = LayoutInflater.from(mContext).inflate(R.layout.listener, parent, false);
holder.message = (TextView) convertView.findViewById(R.id.text1);
convertView.setTag(holder);
}
else
holder = (ViewHolder) convertView.getTag();
Log.wtf("message", message.getMessage());
//holder.message.setText(message.getMessage());
holder.message.setText("lol");
LayoutParams lp = (LayoutParams) holder.message.getLayoutParams();
//Check whether message is mine to show green background and align to right
if(message.isMine())
{
holder.message.setBackgroundResource(R.drawable.speech_bubble_green);
lp.gravity = Gravity.RIGHT;
}
//If not mine then it is from sender to show orange background and align to left
else
{
holder.message.setBackgroundResource(R.drawable.speech_bubble_orange);
lp.gravity = Gravity.LEFT;
}
holder.message.setLayoutParams(lp);
//holder.message.setTextColor(R.color.textColor);
return convertView;
}
private static class ViewHolder
{
TextView message;
}
@Override
public long getItemId(int position) {
//Unimplemented, because we aren't using Sqlite.
return position;
}
}
我的调试器导致变量：
holder ChattingAdapter$ViewHolder (id=830019560368)
this ChattingAdapter (id=830019493992)
message ChatMessage (id=830019492960)
position 0
convertView LinearLayout (id=830019561504)
parent ListView (id=830018556296)
我的Xml布局： listitem.xml
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/text1"
android:background="@drawable/speech_bubble_green"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:singleLine="false"
android:textStyle="bold" />
listener.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:padding="10dip"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ListView
android:id="@android:id/list"
android:layout_width="wrap_content"
android:layout_height="0px"
android:layout_weight="1"
android:transcriptMode="normal"
android:stackFromBottom="true"
android:fadingEdge="none" android:padding="4dp"
android:fastScrollEnabled="true" android:smoothScrollbar="false"
android:focusable="true"/>
<LinearLayout android:layout_width="fill_parent"
android:layout_height="wrap_content" android:orientation="horizontal"
android:gravity="center_vertical"
android:padding="4dp">
<EditText android:id="@+id/chat_input"
android:layout_width="0dip"
android:layout_height="fill_parent"
android:layout_weight="1"
android:maxLines="5"
android:inputType="textShortMessage|textAutoCorrect|textMultiLine|textCapSentences"
android:imeOptions="actionSend|flagNoExtractUi"
android:cursorVisible="true"
android:hint="Enter message" />
<Button android:id="@+id/chat_send_message"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="send" />
</LinearLayout>
</LinearLayout>
我的堆栈跟踪：
02-21 16:48:36.008: E/Trace(18696): error opening trace file: No such file or directory (2)
02-21 16:49:00.008: A/Service(18696): connected
02-21 16:52:07.508: A/message(18696): Hello
02-21 16:52:26.018: E/AndroidRuntime(18696): FATAL EXCEPTION: main
02-21 16:52:26.018: E/AndroidRuntime(18696): java.lang.NullPointerException
02-21 16:52:26.018: E/AndroidRuntime(18696): at com.example.konnect.ChattingAdapter.getView(ChattingAdapter.java:49)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.AbsListView.obtainView(AbsListView.java:2273)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.ListView.makeAndAddView(ListView.java:1769)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.ListView.fillUp(ListView.java:706)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.ListView.layoutChildren(ListView.java:1626)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.AbsListView.onLayout(AbsListView.java:2108)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.View.layout(View.java:13754)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.ViewGroup.layout(ViewGroup.java:4364)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1649)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1507)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.LinearLayout.onLayout(LinearLayout.java:1420)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.View.layout(View.java:13754)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.ViewGroup.layout(ViewGroup.java:4364)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.View.layout(View.java:13754)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.ViewGroup.layout(ViewGroup.java:4364)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1649)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1507)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.LinearLayout.onLayout(LinearLayout.java:1420)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.View.layout(View.java:13754)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.ViewGroup.layout(ViewGroup.java:4364)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.View.layout(View.java:13754)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.ViewGroup.layout(ViewGroup.java:4364)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1868)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1689)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4214)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.Choreographer.doCallbacks(Choreographer.java:555)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.Choreographer.doFrame(Choreographer.java:525)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.os.Handler.handleCallback(Handler.java:615)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.os.Handler.dispatchMessage(Handler.java:92)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.os.Looper.loop(Looper.java:137)
02-21 16:52:26.018: E/AndroidRuntime(18696): at android.app.ActivityThread.main(ActivityThread.java:4931)
02-21 16:52:26.018: E/AndroidRuntime(18696): at java.lang.reflect.Method.invokeNative(Native Method)
02-21 16:52:26.018: E/AndroidRuntime(18696): at java.lang.reflect.Method.invoke(Method.java:511)
02-21 16:52:26.018: E/AndroidRuntime(18696): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
02-21 16:52:26.018: E/AndroidRuntime(18696): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558)
02-21 16:52:26.018: E/AndroidRuntime(18696): at dalvik.system.NativeStart.main(Native Method)
02-21 16:52:31.008: E/Trace(18898): error opening trace file: No such file or directory (2)
在添加新消息时调用自定义适配器的函数：
ArrayList<ChatMessage> messagex= new ArrayList<ChatMessage>();;
ChattingAdapter adaptex;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listener);
messagex.add(new ChatMessage("Hello", false));
adaptex = new ChattingAdapter(getApplicationContext(),messagex);
setListAdapter(adaptex);
Button send_button = (Button) findViewById(R.id.chat_send_message);
sender_message = (EditText) findViewById(R.id.chat_input);
send_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
msg = sender_message.getText().toString();
if(!(msg.length()==0)){
messagex.add(new ChatMessage(msg, true));
//addNewMessage(new ChatMessage(msg, true));
adaptex.notifyDataSetChanged();
getListView().setSelection(messagex.size()-1);
}
}});
ChatMessage类：
public class ChatMessage {
String message;
/**
* boolean to determine, who is sender of this message
*/
boolean isMine;
// boolean isStatusMessage;
/**
* Constructor to make a Message object
*/
public ChatMessage(String message, boolean isMine) {
super();
this.message = message;
this.isMine = isMine;
// this.isStatusMessage = false;
}
/**
* Constructor to make a status Message object
* consider the parameters are swaped from default Message constructor,
* not a good approach but have to go with it.
*/
public ChatMessage(boolean status, String message) {
super();
this.message = message;
this.isMine = false;
//this.isStatusMessage = status;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public boolean isMine() {
return isMine;
}
public void setMine(boolean isMine) {
this.isMine = isMine;
}
/**
public boolean isStatusMessage() {
return isStatusMessage;
}
public void setStatusMessage(boolean isStatusMessage) {
this.isStatusMessage = isStatusMessage;
}
*/
}
答案 0 :(得分：6)
你有
convertView = LayoutInflater.from(mContext).inflate(R.layout.listener, parent, false);
然后
holder.message = (TextView) convertView.findViewById(R.id.text1);
但是您的listitem.xml而非listener.xml中的id text1的文字视图会膨胀。
listitem.xml
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/text1"
因此您初始化失败
holder.message = (TextView) convertView.findViewById(R.id.text1);
因此NullPointerException @
holder.message.setText("lol");
解决方案：转到
convertView = LayoutInflater.from(mContext).inflate(R.layout.listitem, parent, false);
答案 1 :(得分：1)
更改：
convertView = LayoutInflater.from(mContext).inflate(R.layout.listener, parent, false);
到：
convertView = LayoutInflater.from(mContext).inflate(R.layout.listitem, parent, false);