RecommendItem.Java
public class RecommendItem {
private String name;
private String type;
private String address;
private Bitmap avatar;
public RecommendItem(String name, String type, String address, Bitmap avatar) {
this.name = name;
this.type = type;
this.address = address;
this.avatar = avatar;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public Bitmap getAvatar() {
return avatar;
}
public void setAvatar(Bitmap avatar) {
this.avatar = avatar;
}
}
FoodRecommendAdapter.Java 公共类FoodRecommendAdapter扩展了ArrayAdapter {
private Context context;
private int reID;
private ArrayList<RecommendItem> recommendItems;
public FoodRecommendAdapter(Context context, int resource, ArrayList<RecommendItem> data) {
super(context, resource, data);
this.context = context;
this.reID = resource;
this.recommendItems = data;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = null;
if (convertView == null) {
LayoutInflater layoutInflater = ((Activity) this.context).getLayoutInflater();
convertView = layoutInflater.inflate(this.reID, parent, false);
return convertView;
}
row = convertView;
RecommendItem item = recommendItems.get(position);
ImageView imageView = (ImageView) row.findViewById(R.id.iv_recommend);
imageView.setImageBitmap(item.getAvatar());
TextView textViewName =(TextView) row.findViewById(R.id.tv_name);
textViewName.setText(item.getName());
TextView textViewType =(TextView) row.findViewById(R.id.tv_type);
textViewType.setText(item.getType());
TextView textViewAddress =(TextView) row.findViewById(R.id.tv_name);
textViewAddress.setText(item.getName());
return row;
}
}
FoodRecommed.Java
public class FoodRecommend extends AppCompatActivity {
ListView listViewFood;
ArrayList<RecommendItem> recommendItems;
FoodRecommendAdapter foodRecommendAdapter;
Button btnMap, btnMyList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_food_recommend);
initComponents();
loadData();
}
private void loadData() {
recommendItems = new ArrayList<>();
recommendItems.add(new RecommendItem("Bánh Mì","Food","26 Lê Thị Riêng, Ben Thanh, District 1",
BitmapFactory.decodeResource(getResources(),R.drawable.banhmi)));
recommendItems.add(new RecommendItem("Phở","Food","19 Nguyễn Thị Minh Khai, District 1",
BitmapFactory.decodeResource(getResources(),R.drawable.pho)));
recommendItems.add(new RecommendItem("Bún Thịt Nướng","Food","195 Cô Giang, District 1",
foodRecommendAdapter = new FoodRecommendAdapter(this, R.layout.layout_item_recommend, recommendItems);
listViewFood.setAdapter(foodRecommendAdapter);
}
private void initComponents() {
listViewFood = (ListView) this.findViewById(R.id.food_recommend_list);
btnMap = (Button) findViewById(R.id.btn_map);
btnMyList = (Button) findViewById(R.id.btn_mylists);
}
public void mapActivity(View view) {
Intent intent = new Intent(FoodRecommend.this, MapsActivity.class);
startActivity(intent);
}
public void mylistActivity(View view) {
Intent intent = new Intent(FoodRecommend.this, MyList.class);
startActivity(intent);
}
}
监视器出错
06-20 09:30:23.735 9834-9834/com.example.phy.hochiminhcity E/InputEventReceiver: Exception dispatching input event.
06-20 09:30:23.736 9834-9834/com.example.phy.hochiminhcity D/AndroidRuntime: Shutting down VM
06-20 09:30:23.738 9834-9834/com.example.phy.hochiminhcity E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.phy.hochiminhcity, PID: 9834
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageBitmap(android.graphics.Bitmap)' on a null object reference
at com.example.phy.hochiminhcity.FoodRecommendAdapter.getView(FoodRecommendAdapter.java:43)
at android.widget.AbsListView.obtainView(AbsListView.java:2363)
at android.widget.ListView.makeAndAddView(ListView.java:1970)
at android.widget.ListView.fillDown(ListView.java:704)
at android.widget.ListView.fillGap(ListView.java:668)
at android.widget.AbsListView.trackMotionScroll(AbsListView.java:5186)
at android.widget.ListView.trackMotionScroll(ListView.java:1889)
at android.widget.AbsListView.scrollIfNeeded(AbsListView.java:3568)
at android.widget.AbsListView.onTouchMove(AbsListView.java:3977)
at android.widget.AbsListView.onTouchEvent(AbsListView.java:3802)
at android.view.View.dispatchTouchEvent(View.java:10023)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2626)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2307)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2632)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2321)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2632)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2321)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2632)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2321)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2632)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2321)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2632)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2321)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2632)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2321)
at com.android.internal.policy.DecorView.superDispatchTouchEvent(DecorView.java:413)
at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1808)
at android.app.Activity.dispatchTouchEvent(Activity.java:3061)
at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:71)
at com.android.internal.policy.DecorView.dispatchTouchEvent(DecorView.java:375)
at android.view.View.dispatchPointerEvent(View.java:10243)
at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4438)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4306)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3853)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3906)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3872)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3999)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3880)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4056)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3853)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3906)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3872)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3880)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3853)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6246)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6220)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6181)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:6349)
at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
at android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(Native Method)
06-20 09:30:23.739 9834-9834/com.example.phy.hochiminhcity E/AndroidRuntime: at android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:176)
at android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImpl.java:6320)
at android.view.ViewRootImpl$ConsumeBatchedInputRunnable.run(ViewRootImpl.java:6372)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:874)
at android.view.Choreographer.doCallbacks(Choreographer.java:686)
at android.view.Choreographer.doFrame(Choreographer.java:615)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:860)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
06-20 09:30:23.748 1696-3221/system_process W/ActivityManager: Force finishing activity com.example.phy.hochiminhcity/.FoodRecommend
我不知道为什么它在“空对象引用”上说“尝试调用虚方法'void android.widget.ImageView.setImageBitmap（android.graphics.Bitmap）'，而我已经在FoodRecommend中初始化了位图类
答案 0 :(得分：2)
像这样更改你的代码
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
holder = new ViewHolder();
LayoutInflater layoutInflater = ((Activity)
this.context).getLayoutInflater();
convertView = layoutInflater.inflate(this.reID, parent, false);
holder.imageView = (ImageView) convertView .findViewById(R.id.iv_recommend);
holder.textViewName =(TextView) convertView .findViewById(R.id.tv_name);
holder.textViewType =(TextView) convertView .findViewById(R.id.tv_type);
holder.textViewAddress =(TextView) convertView .findViewById(R.id.tv_name);
convertView.setTag(holder);
} else {
holder = (ViewHolder)convertView.getTag();
}
RecommendItem item = recommendItems.get(position);
holder.imageView.setImageBitmap(item.getAvatar());
holder.textViewName.setText(item.getName());
holder.textViewType.setText(item.getType());
holder.textViewAddress.setText(item.getName());
return convertView;
}
class ViewHolder {
public TextView textViewType;
public ImageView imageView;
public TextView textViewType;
public TextView textViewAddress;
}
答案 1 :(得分：1)
您必须没有正确初始化ImageView。您必须从不正确的布局中提供引用ID。确保xml布局中的引用ID与预期的ImageView匹配。