我是 Eclipse/Android 的新手。我有很多错误，但无法捕捉到它们..请需要帮助。
package chintan.khetiya.sqlite.cursor;
import java.util.ArrayList;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class Product_Screen extends Activity{
Button add_prod_btn;
ListView Product_listview;
ArrayList<Product> product_data = new ArrayList<Product>();
Product_Adapter pAdapter;
DatabaseHandler db;
String Toast_msg;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.products);
try {
Product_listview = (ListView) findViewById(R.id.prod_list);
Product_listview.setItemsCanFocus(false);
add_prod_btn = (Button) findViewById(R.id.add_prod_btn);
Set_Referash_Data();
} catch (Exception e) {
// TODO: handle exception
Log.e("Error", "" + e);
}
add_prod_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent add_product = new Intent(Product_Screen.this,
Add_Update_Prod.class);
add_product.putExtra("called", "add");
add_product.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP
| Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(add_product);
finish();
}
});
}
public void Set_Referash_Data() {
product_data.clear();
db = new DatabaseHandler(this);
ArrayList<Product> product_array_from_db = db.Get_Products();
for (int i = 0; i < product_array_from_db.size(); i++) {
int tidno1 = product_array_from_db.get(i).get_prodID();
String prod_name = product_array_from_db.get(i).get_prodName();
String desc = product_array_from_db.get(i).get_prodDesc();
Product prod = new Product();
prod.set_prodID(tidno1);
prod.set_prodName(prod_name);
prod.set_prodDesc(desc);
product_data.add(prod);
}
db.close();
pAdapter = new Product_Adapter(Product_Screen.this, R.layout.listview_row,
product_data);
Product_listview.setAdapter(pAdapter);
pAdapter.notifyDataSetChanged();
}
public void Show_Toast(String msg) {
Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_LONG).show();
}
@Override
public void onResume() {
// TODO Auto-generated method stub
super.onResume();
Set_Referash_Data();
}
public class Product_Adapter extends ArrayAdapter<Product> {
Activity activity;
int layoutResourceId;
Product product;
ArrayList<Product> data = new ArrayList<Product>();
public Product_Adapter(Activity act, int layoutResourceId,
ArrayList<Product> data) {
super(act, layoutResourceId, data);
this.layoutResourceId = layoutResourceId;
this.activity = act;
this.data = data;
notifyDataSetChanged();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row1 = convertView;
UserHolder holder = null;
if (row1 == null) {
LayoutInflater inflater = LayoutInflater.from(activity);
row1 = inflater.inflate(layoutResourceId, parent, false);
holder = new UserHolder();
holder.prod = (TextView) row1.findViewById(R.id.user_prod_name_txt);
holder.desc = (TextView) row1.findViewById(R.id.user_prod_desc_txt);
holder.edit = (Button) row1.findViewById(R.id.btn_prod_update);
holder.delete = (Button) row1.findViewById(R.id.btn_prod_delete);
row1.setTag(holder);
} else {
holder = (UserHolder) row1.getTag();
}
product = data.get(position);
holder.edit.setTag(product.get_prodID());
holder.delete.setTag(product.get_prodID());
holder.prod.setText(product.get_prodName());
holder.desc.setText(product.get_prodDesc());
holder.edit.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Log.i("Edit Button Clicked", "**********");
Intent update_product = new Intent(activity,
Add_Update_Prod.class);
update_product.putExtra("called", "update");
update_product.putExtra("PROD_ID", v.getTag().toString());
activity.startActivity(update_product);
}
});
holder.delete.setOnClickListener(new OnClickListener() {
@Override
public void onClick(final View v) {
// TODO Auto-generated method stub
// show a message while loader is loading
AlertDialog.Builder adb = new AlertDialog.Builder(activity);
adb.setTitle("Alerta !");
adb.setMessage("Está a punto de eliminarlo ");
final int prod_id = Integer.parseInt(v.getTag().toString());
adb.setNegativeButton("Cancelar", null);
adb.setPositiveButton("Eliminar",
new AlertDialog.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int which) {
// MyDataObject.remove(positionToRemove);
DatabaseHandler dBHandler = new DatabaseHandler(
activity.getApplicationContext());
dBHandler.Delete_Product(prod_id);
Product_Screen.this.onResume();
}
});
adb.show();
}
});
return row1;
}
class UserHolder {
TextView prod;
TextView desc;
Button edit;
Button delete;
}
}
}
然后是错误。
E/AndroidRuntime(788): FATAL EXCEPTION: main
E/AndroidRuntime(788): java.lang.NullPointerException
E/AndroidRuntime(788): at chintan.khetiya.sqlite.cursor.Product_Screen$Product_Adapter.getView(Product_Screen.java:141)
E/AndroidRuntime(788): at android.widget.AbsListView.obtainView(AbsListView.java:2159)
E/AndroidRuntime(788): at android.widget.ListView.measureHeightOfChildren(ListView.java:1246)
E/AndroidRuntime(788): at android.widget.ListView.onMeasure(ListView.java:1158)
E/AndroidRuntime(788): at android.view.View.measure(View.java:15518)
E/AndroidRuntime(788): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
E/AndroidRuntime(788): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
E/AndroidRuntime(788): at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
E/AndroidRuntime(788): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
E/AndroidRuntime(788): at android.view.View.measure(View.java:15518)
E/AndroidRuntime(788): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
E/AndroidRuntime(788): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
E/AndroidRuntime(788): at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
E/AndroidRuntime(788): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
E/AndroidRuntime(788): at android.view.View.measure(View.java:15518)
E/AndroidRuntime(788): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
E/AndroidRuntime(788): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
E/AndroidRuntime(788): at android.view.View.measure(View.java:15518)
E/AndroidRuntime(788): at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
E/AndroidRuntime(788): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
E/AndroidRuntime(788): at android.view.View.measure(View.java:15518)
E/AndroidRuntime(788): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
E/AndroidRuntime(788): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
E/AndroidRuntime(788): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176)
E/AndroidRuntime(788): at android.view.View.measure(View.java:15518)
E/AndroidRuntime(788): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874)
E/AndroidRuntime(788): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
E/AndroidRuntime(788): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
E/AndroidRuntime(788): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
E/AndroidRuntime(788): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
E/AndroidRuntime(788): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
E/AndroidRuntime(788): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
E/AndroidRuntime(788): at android.view.Choreographer.doFrame(Choreographer.java:532)
E/AndroidRuntime(788): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
E/AndroidRuntime(788): at android.os.Handler.handleCallback(Handler.java:725)
E/AndroidRuntime(788): at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime(788): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(788): at android.app.ActivityThread.main(ActivityThread.java:5041)
E/AndroidRuntime(788): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(788): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(788): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
E/AndroidRuntime(788): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
E/AndroidRuntime(788): at dalvik.system.NativeStart.main(Native Method)