Java 使用带有自定义类的setadapter的nullpointerexception
我试图显示imageview和textview的组合，但在实际显示数据时不断出错 我试图从用户那里获取输入以搜索一些东西，然后运行一些后台方法来提取数据。然后，我将有两个充满数据的数组，然后创建Item对象并将其传递给我的自定义适配器类 我正试图利用方形毕加索从URL加载一些图像。我认为这可能是问题所在，但错误表明它来自setadapter 很抱歉发布了这么多代码 这是我的MainActivity.javaJava 使用带有自定义类的setadapter的nullpointerexception,java,android,nullpointerexception,Java,Android,Nullpointerexception,我试图显示imageview和textview的组合，但在实际显示数据时不断出错 我试图从用户那里获取输入以搜索一些东西，然后运行一些后台方法来提取数据。然后，我将有两个充满数据的数组，然后创建Item对象并将其传递给我的自定义适配器类 我正试图利用方形毕加索从URL加载一些图像。我认为这可能是问题所在，但错误表明它来自setadapter 很抱歉发布了这么多代码 这是我的MainActivity.java public class MainActivity extends ActionBarA
public class MainActivity extends ActionBarActivity {
String url = "https://www.google.com/search?hl=en&tbm=shop&q=";
ProgressDialog mProgressDialog;
float x1,x2;
float y1, y2;
ImageButton button;
int buttonPressed = 0;
private ListView listView1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (ImageButton) findViewById(R.id.search_button);
button.setOnClickListener(new OnClickListener()
{
public void onClick(View arg0)
{
new Search().execute();
}
});
}
private class Search extends AsyncTask<Void, Void, Void> {
String title = "blah";
String prices[] = new String[10];
String description[] = new String[10];
String stores[] = new String[10];
String full[] = new String[10]; // change this 40
String linksContainer[] = new String[10];
String imgContainer[] = new String[10];
@Override
protected void onPreExecute() {
super.onPreExecute();
mProgressDialog = new ProgressDialog(MainActivity.this);
mProgressDialog.setTitle("Salert");
mProgressDialog.setMessage("Searching...");
mProgressDialog.setIndeterminate(false);
mProgressDialog.show();
}
@Override
protected Void doInBackground(Void... params) {
try {
EditText edit = (EditText) findViewById(R.id.search_field);
String search = edit.getText().toString().replaceAll("\\s","\\+");
// Connect to the web site
Document document = Jsoup.connect(url+search).get();
// Get the html document title
Elements stuff = document.select("div[class=psgicont]");
Iterator<Element> iter = stuff.iterator();
Element temp;
//String str = "";
//int index, index2;
Elements links = document.select("a[class=psgiimg]");
Iterator<Element> iterImage = links.iterator();
Element tempImage;
for(int i = 0; i < 10; i++) // change this to 40
{
temp = iter.next();
full[i] = temp.text();
/*
index = str.indexOf('$');
index2 = str.indexOf("from");
description[i] = str.substring(0, index - 1);
prices[i] = str.substring(index,index2 - 1);
stores[i] = str.substring(index2 + 5, str.length());
full[i] = description[i] + "\n" + prices[i] + " from " + stores[i];
*/
}
for(int j=0; j < 10; j++)
{
tempImage = iterImage.next();
linksContainer[j] = tempImage.attr("abs:href");
//Log.d("message", linksContainer[j]);
}
for (int k=0; k < 10; k++)
{
String url = linksContainer[k];
Document document2 = Jsoup.connect(url).get();
Elements link = document2.select("div[id=pp-altimg-init-main] > img");
imgContainer[k] = link.attr("src");
Log.d("img link", imgContainer[k]);
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void result)
{
/*
ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this,
R.layout.list_view, R.id.label, full);
ListView listView = (ListView) findViewById(R.id.list);
listView.setAdapter(adapter);*/
Item item_data[] = new Item[]
{
new Item(imgContainer[0], full[0]),
new Item(imgContainer[1], full[1]),
new Item(imgContainer[2], full[2]),
new Item(imgContainer[3], full[3]),
new Item(imgContainer[4], full[4]),
new Item(imgContainer[5], full[5]),
new Item(imgContainer[6], full[6]),
new Item(imgContainer[7], full[7]),
new Item(imgContainer[8], full[8]),
new Item(imgContainer[9], full[9])
};
ItemAdapter adapter = new ItemAdapter(MainActivity.this, R.layout.list_view, item_data);
listView1 = (ListView)findViewById(R.id.listView1);
listView1.setAdapter(adapter);
mProgressDialog.dismiss();
buttonPressed ++;
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#303541"
android:id="@+id/listView1">
<ImageView android:id="@+id/img"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:gravity="center_vertical"
android:layout_alignParentTop="true"
android:layout_alignParentBottom="true"
android:layout_marginRight="15dp"
android:layout_marginTop="5dp"
android:layout_marginBottom="5dp"
/>
<TextView android:id="@+id/label"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center_vertical"
android:layout_alignParentTop="true"
android:layout_alignParentBottom="true"
android:textStyle="bold"
android:textSize="22dp"
android:textColor="#000000"
android:layout_marginTop="5dp"
android:layout_marginBottom="5dp" />
<Button android:text="@string/add"
android:id="@+id/addButton"
android:layout_marginTop="2dip"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="addItemHandler"
android:gravity="right" />
</ListView>
更新问题可能来自ItemAdapter类中的picasso.withcontext行。这就是我实际显示url图像的地方。在活动xml中，您声明了一个id为android:id=@+id/list的ListView，但在AsyncTask中，您正在查找listView1=ListViewfindViewByIdR.id.listView1；您正在将其用作行_item.xml的根。我猜你想改变 listView1=ListViewfindViewByIdR.id.listView1 与 listView1=ListViewfindViewByIdR.id.list
并去掉list_view.xml中的ListView，添加了logcat。上面的几行仅仅是获取数据的后台执行。@JeffNguyen MainActivity.java？listView1.setAdapteradapter中的第174行是什么；我从未见过在列表中包含子对象的列表视图xml@JeffNguyenlistview1为空。有子元素的listview？是的，我试过更改那一行的id。如果我没有列出，它会给我错误LinearLayout无法转换为android.widget.ImageView为什么要将LinearLayout转换为ImageView？摆脱getView中的强制转换，使用膨胀视图检索itI中的项目我这样做是因为在我的ItemAdapter类中-我使用Picasso.withcontext的行中。。。原始视图有问题-因此我使用ImageView。我将上面的ItemAdapter.is Picasso.更新为需要ImageView？然后他应该在支架内添加ImageView，而不是提供行，他应该传递holderInstance.ImageView@拉古南丹：谢谢你的纪录片
package com.example.salert;
public class Item{
public String url;
public String description;
public Item(){
super();
}
public Item(String url, String description){
super();
this.url = url;
this.description = description;
}
}
<?xml version="1.0" encoding="utf-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#303541"
android:id="@+id/listView1">
<ImageView android:id="@+id/img"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:gravity="center_vertical"
android:layout_alignParentTop="true"
android:layout_alignParentBottom="true"
android:layout_marginRight="15dp"
android:layout_marginTop="5dp"
android:layout_marginBottom="5dp"
/>
<TextView android:id="@+id/label"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center_vertical"
android:layout_alignParentTop="true"
android:layout_alignParentBottom="true"
android:textStyle="bold"
android:textSize="22dp"
android:textColor="#000000"
android:layout_marginTop="5dp"
android:layout_marginBottom="5dp" />
<Button android:text="@string/add"
android:id="@+id/addButton"
android:layout_marginTop="2dip"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="addItemHandler"
android:gravity="right" />
</ListView>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.bigbang.salertapp.MainActivity"
android:background ="@drawable/logo" >
<EditText
android:id="@+id/search_field"
android:layout_alignParentLeft="true"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingLeft="12dp"
android:singleLine="true"
android:textColor="#737373"
android:background="@drawable/search"
android:hint="@string/search"
/>
<ImageButton android:id="@+id/search_button"
android:layout_width="20dip"
android:layout_height="20dip"
android:layout_marginRight="12dip"
android:layout_marginTop="2dip"
android:layout_alignRight="@+id/search_field"
android:layout_alignTop="@+id/search_field"
android:layout_alignParentRight="true"
android:contentDescription="@string/searchbuttonCD"
android:background="@drawable/sbicon1"
/>
<ListView
android:layout_marginTop="2dip"
android:id="@+id/list"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/search_field"
android:background="#303541"/>
</RelativeLayout>
07-24 02:41:21.014: W/dalvikvm(6505): threadid=1: thread exiting with uncaught exception (group=0x413e2438)
07-24 02:41:21.024: E/AndroidRuntime(6505): FATAL EXCEPTION: main
07-24 02:41:21.024: E/AndroidRuntime(6505): java.lang.NullPointerException
07-24 02:41:21.024: E/AndroidRuntime(6505): at com.example.salert.MainActivity$Search.onPostExecute(MainActivity.java:174)
07-24 02:41:21.024: E/AndroidRuntime(6505): at com.example.salert.MainActivity$Search.onPostExecute(MainActivity.java:1)
07-24 02:41:21.024: E/AndroidRuntime(6505): at android.os.AsyncTask.finish(AsyncTask.java:631)
07-24 02:41:21.024: E/AndroidRuntime(6505): at android.os.AsyncTask.access$600(AsyncTask.java:177)
07-24 02:41:21.024: E/AndroidRuntime(6505): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
07-24 02:41:21.024: E/AndroidRuntime(6505): at android.os.Handler.dispatchMessage(Handler.java:99)
07-24 02:41:21.024: E/AndroidRuntime(6505): at android.os.Looper.loop(Looper.java:137)
07-24 02:41:21.024: E/AndroidRuntime(6505): at android.app.ActivityThread.main(ActivityThread.java:4905)
07-24 02:41:21.024: E/AndroidRuntime(6505): at java.lang.reflect.Method.invokeNative(Native Method)
07-24 02:41:21.024: E/AndroidRuntime(6505): at java.lang.reflect.Method.invoke(Method.java:511)
07-24 02:41:21.024: E/AndroidRuntime(6505): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
07-24 02:41:21.024: E/AndroidRuntime(6505): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
07-24 02:41:21.024: E/AndroidRuntime(6505): at dalvik.system.NativeStart.main(Native Method)