我有一个Claim对象列表，每个声明对象都使用名称和费用列表进行初始化。
我为索赔的列表视图制作了一个适配器。我现在要做的是为费用创建一个适配器。由于每个声明都有自己的费用列表，我不能只是制作一般的适配器。我需要为特定的索赔制作适配器，或者我想到这个错误？这就是我做的..
必须清除＆lt;我的问题是：如何使用费用为初始化列表创建一个适配器，并打开该列表视图以查看特定声明的费用，当我点击它时？
package app.zioueche_travelexpense;
import java.util.ArrayList;
import java.util.Collection;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.PopupMenu;
import android.widget.Toast;
//figure out how to add claim in different page. so we can add date range.
public class AddClaim extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.add_claim);
//adapter for claim view this one works. it is the expenses one that i do not know how to implement
ListView listView = (ListView) findViewById(R.id.claimListView);
Collection<Claim> claims = ClaimListController.getClaimList().getClaim();
final ArrayList<Claim> list = new ArrayList<Claim>(claims);
final ArrayAdapter<Claim> claimAdapter = new ArrayAdapter<Claim>(this, android.R.layout.simple_list_item_1, list);
listView.setAdapter(claimAdapter);
//Added observer pattern
ClaimListController.getClaimList().addListener(new Listener(){
@Override
public void update(){
list.clear();
Collection<Claim> claims = ClaimListController.getClaimList().getClaim();
list.addAll(claims);
claimAdapter.notifyDataSetChanged();
}
});
//SINGLE TAP FUNCTION
listView.setOnItemClickListener(new OnItemClickListener(){
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
//adapter expenses I DO NOT KNOW HOW TO IMPLEMENT THIS
ListView expView = (ListView) findViewById(R.id.ExpenseListView);
Collection<Expense> expenses = list.get(position).getExpenses();
final ArrayList<Expense> expense = new ArrayList<Expense>(expenses);
final ArrayAdapter<Expense> expAdap = new ArrayAdapter<Expense>(AddClaim.this, android.R.layout.simple_list_item_1, expense);
expView.setAdapter(expAdap); //THIS IS MY LINE 64
}
});
//LONG CLICK FUNCTIONS
listView.setOnItemLongClickListener(new OnItemLongClickListener(){
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view,
int position, long id) {
final int finalPosition = position;
PopupMenu popup = new PopupMenu(AddClaim.this, view);
popup.getMenuInflater().inflate(R.menu.add_claim, popup.getMenu());
popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
public boolean onMenuItemClick(MenuItem item) {
//DELETE button check.
if (item.getTitle().equals("Delete")){
AlertDialog.Builder adb = new AlertDialog.Builder(AddClaim.this);
adb.setMessage("Delete "+ list.get(finalPosition).toString()+"?");
adb.setCancelable(true);
adb.setPositiveButton("Delete",new OnClickListener(){
@Override
public void onClick(DialogInterface dialog, int which) {
Claim claim = list.get(finalPosition);
ClaimListController.getClaimList().deleteClaim(claim);
}
});
adb.setNegativeButton("Cancel",new OnClickListener(){
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
adb.show();
}//end of delete button check
//START of ADD EXPENSE check
if (item.getTitle().equals("Add Expense")){
Intent intent = new Intent(AddClaim.this, ExpenseAdd.class);
intent.putExtra("somename", finalPosition);
startActivity(intent);
}
//end of add expense check
return true;
}
});
popup.show();
return false;
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.add_claim, menu);
return true;
}
protected void onDeleteClick(final int position, final ArrayList<Claim> list){
AlertDialog.Builder adb = new AlertDialog.Builder(AddClaim.this);
adb.setMessage("Delete "+ list.get(position).toString()+"?");
adb.setCancelable(true);
adb.setPositiveButton("Delete",new OnClickListener(){
@Override
public void onClick(DialogInterface dialog, int which) {
Claim claim = list.get(position);
ClaimListController.getClaimList().deleteClaim(claim);
}
});
adb.setNegativeButton("Cancel",new OnClickListener(){
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
adb.show();
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void addClaimView(MenuItem item){
Toast.makeText(this, "going to claim creation page", Toast.LENGTH_SHORT).show();
setContentView(R.layout.claim_add_page);
}
public void addClaims(View v){
ClaimListController ct = new ClaimListController();
EditText textView = (EditText) findViewById(R.id.add_claim_field);
String added = textView.getText().toString();
if (!TextUtils.isEmpty(added)){
final String t = format("added",added);
ct.addClaim(new Claim(added));
Toast.makeText(this, t, Toast.LENGTH_SHORT).show();
textView.setText("");
setContentView(R.layout.claim_list);
//Intent intent = new Intent(MainActivity.this, AddClaim.class);
//startActivity(intent);
}else{
Toast.makeText(AddClaim.this,"Please type something before adding", Toast.LENGTH_SHORT).show();
}
}
private String format(String string, String added) {
String formats = string +" "+ added;
return formats;
}
}
正如你所看到的，我为onclick方法中的费用制作了listview适配器，因为我需要这个位置来从特定索赔中获取费用清单。
如何执行此操作/当我运行此代码时，我在第64行获得空指针异常。
这是log cat。
01-24 02:01:15.434: E/AndroidRuntime(1099): FATAL EXCEPTION: main
01-24 02:01:15.434: E/AndroidRuntime(1099): java.lang.NullPointerException
01-24 02:01:15.434: E/AndroidRuntime(1099): at app.zioueche_travelexpense.AddClaim$2.onItemClick(AddClaim.java:64)
01-24 02:01:15.434: E/AndroidRuntime(1099): at android.widget.AdapterView.performItemClick(AdapterView.java:298)
01-24 02:01:15.434: E/AndroidRuntime(1099): at android.widget.AbsListView.performItemClick(AbsListView.java:1100)
01-24 02:01:15.434: E/AndroidRuntime(1099): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2749)
01-24 02:01:15.434: E/AndroidRuntime(1099): at android.widget.AbsListView$1.run(AbsListView.java:3423)
01-24 02:01:15.434: E/AndroidRuntime(1099): at android.os.Handler.handleCallback(Handler.java:725)
01-24 02:01:15.434: E/AndroidRuntime(1099): at android.os.Handler.dispatchMessage(Handler.java:92)
01-24 02:01:15.434: E/AndroidRuntime(1099): at android.os.Looper.loop(Looper.java:137)
01-24 02:01:15.434: E/AndroidRuntime(1099): at android.app.ActivityThread.main(ActivityThread.java:5041)
01-24 02:01:15.434: E/AndroidRuntime(1099): at java.lang.reflect.Method.invokeNative(Native Method)
01-24 02:01:15.434: E/AndroidRuntime(1099): at java.lang.reflect.Method.invoke(Method.java:511)
01-24 02:01:15.434: E/AndroidRuntime(1099): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-24 02:01:15.434: E/AndroidRuntime(1099): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-24 02:01:15.434: E/AndroidRuntime(1099): at dalvik.system.NativeStart.main(Native Method)
01-24 02:01:17.814: E/Trace(1117): error opening trace file: No such file or directory (2)