Question

我正在编写推特应用程序。我正在为usernames / hashtags创建一个搜索栏，我在将从XML生成的视图添加到当前现有的LinearLayout时遇到了一些麻烦。

这里是Search.java

public class Search extends Activity{

String searchType = "username";

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_search);

    EditText t = (EditText)findViewById(R.id.search_content);
    t.setOnClickListener(onClickSearch);
    t.setWidth(225);

    Button b = (Button)findViewById(R.id.search_button_search);
    b.setOnClickListener(onClickButton);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_search, menu);
    return true;
}

OnClickListener onClickSearch = new OnClickListener(){

    public void onClick(View v) {
        EditText searchContent = (EditText)findViewById(R.id.search_content);
        EditText clickedContent = (EditText)v;
        if((EditText)findViewById(R.id.search_content) == (EditText)v){
            EditText t = (EditText)v;
            t.setText("");
        }

        //EditText searchContent = (EditText)findViewById(R.id.search_content);
        //EditText clickedContent = (EditText)v;

        /*if((Button)v == (Button)findViewById(R.id.search_button_type)){
            EditText t = (EditText)findViewById(R.id.search_content);
            Search.this.searchByUserName(t.getText().toString());
        }

        if((Button)v == (Button)findViewById(R.id.search_button_search)){

        }*/
    }

};

OnClickListener onClickButton = new OnClickListener(){

    public void onClick(View v) {
        //if((Button)v == (Button)findViewById(R.id.search_button_search)){
            EditText t = (EditText)findViewById(R.id.search_content);
            Search s = new Search();
            s.searchByUserName(t.getText().toString());
        //}

        //if((Button)v == (Button)findViewById(R.id.search_button_search)){

        //}
    }

};

public void searchByUserName(String userName){
    //System.out.println("beginning->searchByUserName");
    TwitterHandler handler = new TwitterHandler();
    List<View> views = handler.queryUserName(userName, this);

    LinearLayout ll = (LinearLayout)findViewById(R.id.search_panel);
    for(int i = 0; i < views.size(); i++){
        ll.addView(views.get(i));
    }
}

}

这是XML

<LinearLayout 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:id="@+id/search_panel" >
    <Button
       android:id="@+id/search_button_type"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Search Type"/>

    <EditText
        android:id="@+id/search_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Search Here" >
    </EditText>

    <Button
        android:id="@+id/search_button_search"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Search"/>
</LinearLayout>

我的LogCat告诉我有一个NullPointerException，该进程被强制退出android虚拟设备。请帮助!!!

这是TwitterHandler

public class TwitterHandler extends DefaultHandler{
private final String USER_SEARCH = "https://api.twitter.com/1/users/lookup.xml?screen_name=";

public List<View> queryUserName(String userName, Context context){
    System.out.println("beginning->queryUserName");
    String url = USER_SEARCH + userName;
    //ListView view = new ListView(context);
    List<View> views = new ArrayList<View>();
    Document doc = null;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try {
        System.out.println("in try statement->queryUserName");
        DocumentBuilder db = dbf.newDocumentBuilder();

        InputSource is = new InputSource();
        is.setCharacterStream(new StringReader(url));
        doc = db.parse(is); 

        NodeList nl = doc.getChildNodes();

        for(int i = 0; i < nl.getLength(); i++){
            Element e = (Element)nl.item(i);
            TextView t = new TextView(context);

            String name = "";
            String screenName = "";
            Bitmap bitmap = null;

            Node n = (Node)e.getChild("name");
            name = n.getTextContent();
            t.setText(name);
            views.add(t);

            t = new TextView(context);
            n = (Node)e.getChild("screen_name");
            screenName = n.getTextContent();
            t.setText(screenName);
            views.add(t);

            n = (Node)e.getChild("profile_image_url");
            bitmap = getBitmap(n.getTextContent());
            ImageView imageView = new ImageView(context);
            imageView.setImageBitmap(bitmap);
            views.add(imageView);

        }

    }catch(Exception e){ }
    return views;
}

private Bitmap getBitmap(String imageUrl) throws IOException{
InputStream inputStream = null;
 URL u = new URL(imageUrl);
 URLConnection conn = u.openConnection();

 try{
      HttpURLConnection httpConn = (HttpURLConnection)conn;
      httpConn.setRequestMethod("GET");
      httpConn.connect();

      if (httpConn.getResponseCode() == HttpURLConnection.HTTP_OK) {
          inputStream = httpConn.getInputStream();
      }
 }
 catch (Exception ex) { }

return BitmapFactory.decodeStream(inputStream);

}

}

这是Log

07-26 17:00:24.523: D/AndroidRuntime(335): Shutting down VM
07-26 17:00:24.523: W/dalvikvm(335): threadid=1: thread exiting with uncaught exception     (group=0x40015560)
07-26 17:00:24.533: E/AndroidRuntime(335): FATAL EXCEPTION: main
07-26 17:00:24.533: E/AndroidRuntime(335): java.lang.ClassCastException:   java.util.AbstractList$SubAbstractListRandomAccess
07-26 17:00:24.533: E/AndroidRuntime(335):  at    com.example.twitter.viewer.Search.searchByUserName(Search.java:84)
07-26 17:00:24.533: E/AndroidRuntime(335):  at com.example.twitter.viewer.Search$2.onClick(Search.java:71)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.view.View.performClick(View.java:2485)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.view.View$PerformClick.run(View.java:9080)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.os.Handler.handleCallback(Handler.java:587)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.os.Handler.dispatchMessage(Handler.java:92)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.os.Looper.loop(Looper.java:123)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.app.ActivityThread.main(ActivityThread.java:3683)
07-26 17:00:24.533: E/AndroidRuntime(335):  at java.lang.reflect.Method.invokeNative(Native Method)
07-26 17:00:24.533: E/AndroidRuntime(335):  at java.lang.reflect.Method.invoke(Method.java:507)
07-26 17:00:24.533: E/AndroidRuntime(335):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-26 17:00:24.533: E/AndroidRuntime(335):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-26 17:00:24.533: E/AndroidRuntime(335):  at dalvik.system.NativeStart.main(Native Method)

Answer 1

您正在尝试制作Search Activity的新实例对象。您的contentView不可用，因此您无法使用LinearLayout方法定义searchByUserName。

而只是简单的使用方法名称..

所以替换这些行，

Search s = new Search();
s.searchByUserName(t.getText().toString());

仅限，

searchByUserName(t.getText().toString());

Android 2.3.3：从（LinearLayout）获取LinearLayout时发生崩溃findViewById（R.id。<linear_layout_id>）</linear_layout_id>

1 个答案: