NullPointerException和Android ListView

Question

我想用LinkedList填充ListView。 我认为在我的执行中有些错误..但我找不到什么。

这是梅索德我设置的适配器：

public void refreshListView() { 
    //pManager.simpleSort(); 
    // pManager.getProfiles() 

    LinkedList<Profile> temp = new LinkedList<Profile>(); 
    temp.add(new Profile("hello", "link", true)); // im kind of testing here 
    adapter = new CustomAdapter(getApplicationContext(), temp); 
    list.setAdapter(adapter); 
} 

这是我写的，使用一些教程CustomAdapter。

public class CustomAdapter extends BaseAdapter { 

    private LinkedList<Profile> profiles; 
    private Context context; 

    public CustomAdapter(Context context, LinkedList<Profile> input) { 
     this.context = context; 
     profiles = input; 
    } 

    @Override 
    public int getCount() { 
     if (profiles == null) { 
      return 0; 
     } else { 
      return profiles.size(); 
     } 
    } 

    @Override 
    public Profile getItem(int arg0) { 
     return profiles.get(arg0); 
    } 

    @Override 
    public View getView(int position, View v, ViewGroup parent) { 
     View out = v; 
     if (out == null){ 
      out = new ProfileItemView(context, getItem(position)); 
     } 
     return out; 
    } 

    @Override 
    public long getItemId(int arg0) { 
     return arg0; 
    } 
} 

这是我的自定义视图我写来显示我的个人资料：

public class ProfileItemView extends RelativeLayout { 

    public ProfileItemView(Context context, Profile profile) { 
     super(context, null); 
     LayoutInflater inflater = (LayoutInflater) context 
       .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     inflater.inflate(R.layout.list_item, null, true); 
     ImageView icon = (ImageView) findViewById(R.id.default_icon_view); 
     if (profile.checkDefault()) { 
      icon.setImageResource(R.drawable.ic_launcher); 
     } else { 
      icon.setImageResource(R.drawable.android_icon); 
     } 
     TextView name = (TextView) findViewById(R.id.name_view); 
     name.setText(profile.getName()); 
    } 
} 

而且，这里是一个logcat的：

Shutting down VM 
threadid=1: thread exiting with uncaught exception (group=0x419c52a0) 
FATAL EXCEPTION: main 
java.lang.NullPointerException 
    at com.exp.test.ProfileItemView.<init>(ProfileItemView.java:18) 
    at com.exp.test.CustomAdapter.getView(CustomAdapter.java:37) 
    at android.widget.AbsListView.obtainView(AbsListView.java:2402) 
    at android.widget.ListView.makeAndAddView(ListView.java:1769) 
    at android.widget.ListView.fillDown(ListView.java:672) 
    at android.widget.ListView.fillFromTop(ListView.java:733) 
    at android.widget.ListView.layoutChildren(ListView.java:1622) 
    at android.widget.AbsListView.onLayout(AbsListView.java:2237) 
    at android.view.View.layout(View.java:13840) 
    at android.view.ViewGroup.layout(ViewGroup.java:4372) 
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:948) 
    at android.view.View.layout(View.java:13840) 
    at android.view.ViewGroup.layout(ViewGroup.java:4372) 
    at android.widget.FrameLayout.onLayout(FrameLayout.java:448) 
    at android.view.View.layout(View.java:13840) 
    at android.view.ViewGroup.layout(ViewGroup.java:4372) 
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1649) 
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1507) 
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1420) 
    at android.view.View.layout(View.java:13840) 
    at android.view.ViewGroup.layout(ViewGroup.java:4372) 
    at android.widget.FrameLayout.onLayout(FrameLayout.java:448) 
    at android.view.View.layout(View.java:13840) 
    at android.view.ViewGroup.layout(ViewGroup.java:4372) 
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1948) 
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1758) 
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1042) 
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4329) 
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725) 
    at android.view.Choreographer.doCallbacks(Choreographer.java:555) 
    at android.view.Choreographer.doFrame(Choreographer.java:525) 
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711) 
    at android.os.Handler.handleCallback(Handler.java:615) 
    at android.os.Handler.dispatchMessage(Handler.java:92) 
    at android.os.Looper.loop(Looper.java:137) 
    at android.app.ActivityThread.main(ActivityThread.java:5118) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:511) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:792) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:555) 
    at dalvik.system.NativeStart.main(Native Method) 

Answer 1

需要初始化使用充气看法你的看法目的。 findViewById在当前充气布局中查找视图。

亦通活动上下文

adapter = new CustomAdapter(ActivityName.this, temp); 

在getView

public View getView(int position, View convertView, ViewGroup parent) { 
ViewHolder holder;  
if (convertView == null) { 
convertView = mInflater.inflate(R.layout.lis_item,parent, false); 
holder = new ViewHolder(); 
holder.tv = (TextView) convertView.findViewById(R.id.name_view); 
holder.iv = (ImageView)convertView.findViewById(R.id.default_icon_view);    
convertView.setTag(holder); 
} else { 
    holder = (ViewHolder) convertView.getTag(); 
} 
    Profile profile = profiles.get(position); 
    if (profile.checkDefault()) { 
     holder.iv.setImageResource(R.drawable.ic_launcher); 
    } else { 
     holder.iv.setImageResource(R.drawable.android_icon); 
    } 
     holder.tv.setText(profile.getName()); 
return convertView; 
} 

使用视图支架图案

static class ViewHolder 
{ 
ImageView iv; 
TextView tv; 
} 

在构造

LayoutInflater mInflater; 
public CustomAdapter(Context context, LinkedList<Profile> input) { 
     mInflater = LayoutInflater.fromf(context; 
     profiles = input; 
    } 

然后