我的代码需要帮助，我编写了自定义 ListView 的代码来显示 multi_cars，但 ListView 没有显示我使用 log-cat 跟踪它的任何内容，并且我确信数据库正在执行操作好吧，它的功能与 insert 和 getAlLData 一样，当我跟踪代码时，我发现应用程序访问自定义 ListView 类并仅打印构造函数中的日志语句，并且不再访问函数 View ，然后返回viewcars 类，，我不知道原因是什么，所以它没有显示任何东西 以下代码适用于 viewCars 类:
package com.example.rentalcarsproject;
import java.util.ArrayList;
import java.util.List;
import com.example.rentalcarsproject.my_database.connection ;
import com.example.rentalcarsproject.CustomListView ;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ListView;
public class viewcars extends Activity implements OnItemSelectedListener{
ListView listView;
connection connectionInstance = null;
ArrayList<cars> userArrayList=new ArrayList<cars>();
ArrayAdapter<cars> userArrayAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewcars);
Log.d("viewcars on create ", "okkkkk");
listView=(ListView) findViewById(R.id.listView1);
listView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapter, View view, int position,
long ID) {
// TODO Auto-generated method stub
cars temp=(cars) adapter.getItemAtPosition(position);
Intent i1=new Intent(getApplicationContext(),act1cars.class);
i1.putExtra("car_key", String.valueOf(temp.getCar_key()));
i1.putExtra("car_name", temp.getCar_name().toString());
i1.putExtra("car_model",temp.getCar_model().toString());
i1.putExtra("price", temp.getPrice().toString());
i1.putExtra("location", temp.getLocation().toString());
i1.putExtra("description",temp.getDescription().toString());
i1.putExtra("picture", temp.getPicture().toString());
startActivity(i1);
}
});
connectionInstance=new connection(getApplicationContext());
Log.d("before array", "ok");
ArrayList<cars> retrieveArrayList=new ArrayList<cars>();
Log.d("test1", "ok");
retrieveArrayList=connectionInstance.GetAllData();
Log.d("test2", "ok");
Log.d("Array Size", String.valueOf(retrieveArrayList.size()));
connectionInstance.close();
Log.d("after connection", "ok");
userArrayList=new ArrayList<cars>();//used in custom list view
for(int i=0;i<retrieveArrayList.size();i++)
{
Log.d("inside for loop ", "ok");
cars show=new cars();
show.setCar_name(retrieveArrayList.get(i).getCar_name());
Log.d("CAR_NAME ", retrieveArrayList.get(i).getCar_name());
show.setCar_model(retrieveArrayList.get(i).getCar_model());
show.setPrice(retrieveArrayList.get(i).getPrice());
show.setLocation(retrieveArrayList.get(i).getLocation());
show.setDescription(retrieveArrayList.get(i).getDescription());
show.setPicture(retrieveArrayList.get(i).getPicture());
userArrayList.add(show);
}
Log.d("arrat_for list view Size", String.valueOf(userArrayList.size()));
Log.d("before setadapter", "ok");
listView.setAdapter(new CustomListView(viewcars.this, userArrayList));
// Log.d("after setadapter", "ok");
}
@Override
public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
}
这是自定义 ListView 的代码:
package com.example.rentalcarsproject;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import junit.framework.Test;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class CustomListView extends BaseAdapter {
ImageView picture;
TextView name;
cars attributes;
Context context;
ArrayList<cars> arrayList=new ArrayList<cars>();
public CustomListView(Context _context,ArrayList<cars> _arrayList) {
// TODO Auto-generated constructor stub
context=_context;
arrayList=_arrayList;
Log.d("constructor", "ok");
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return 0;
}
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
// TODO Auto-generated method stub
View view=arg1;
Log.d("inside cutom list view ", "ok");
Log.i("name ", arrayList.get(arg0).getCar_name());
if(view==null)
{
LayoutInflater layoutInflater=(LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view=layoutInflater.inflate(R.layout.customlistview,null); // add this **.xml layout to the custom listView
}
(view.findViewById(R.id.button1))
.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
Log.d("onclick1 ", "ok ");
Intent intent = new Intent(context, test.class);
context.startActivity(intent);
}
});
name=(TextView) view.findViewById(R.id.textView1);
picture=(ImageView) view.findViewById(R.id.imageView1);
attributes=arrayList.get(arg0);
name.setText(String.valueOf(attributes.getCar_name()));
URL url = null;
try {
url = new URL(attributes.getPicture());
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Bitmap bmp = null;
try {
bmp = BitmapFactory.decodeStream(url.openConnection().getInputStream());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
picture.setImageBitmap(bmp);
/******/
return view;
}
}
最佳答案
改变这个
@Override
public int getCount() {
// TODO Auto-generated method stub
return 0;
}
至
@Override
public int getCount() {
// TODO Auto-generated method stub
return arrayList.size();
}
还有
url.openConnection().getInputStream()
应该在线程中或使用asynctask或使用volley
关于java - 为什么 ListView 不显示任何项目，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/20438923/