自定义getView()的{{1}}方法如下：
ListViewAdapter public class ListViewAdapter extends BaseAdapter {
Context mContext;
LayoutInflater mInflater;
ArrayList mArray;
ArrayList<Item> mArray2;
DBHelper mydb;
String dbName;
public ListViewAdapter(Context context, LayoutInflater inflater) {
mContext = context;
mInflater = inflater;
mArray = new ArrayList();
mArray2 = new ArrayList<>();
mydb = new DBHelper(mContext);
}
@Override
public int getCount() {
return mArray.size();
}
@Override
public Object getItem(int position) {
return mArray.get(position);
}
public Item getItem2(int position) { return mArray2.get(position); }
@Override
public long getItemId(int position) {
// your particular data set uses String IDs
// but you have to put something in this method
return position;
}
@Override
public View getView(final int position, View convertView, final ViewGroup parent) {
ViewHolder holder;
// check if the view already exists
// if so, no need to inflate and findViewById again!
if (convertView == null) {
// Inflate the custom row layout from your XML.
convertView = mInflater.inflate(R.layout.list_item, null);
// create a new "Holder" with subviews
holder = new ViewHolder();
holder.itemNameView = (TextView) convertView.findViewById(R.id.item_name);
holder.itemExpiryView = (TextView) convertView.findViewById(R.id.item_expiry);
// Taking care of the buttons
holder.editButton = (Button) convertView.findViewById(R.id.button_edit);
holder.deleteButton = (Button) convertView.findViewById(R.id.button_delete);
// hang onto this holder for future recycling
convertView.setTag(holder);
} else {
// skip all the expensive inflation/findViewById
// and just get the holder you already made
holder = (ViewHolder) convertView.getTag();
}
// Set listener on the buttons
holder.editButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(mContext, "Edit Button CLicked", Toast.LENGTH_SHORT).show();
}
});
holder.deleteButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String name = getItem(position).toString();
int id = mydb.getID(dbName, name);
mydb.deleteItem(dbName, id);
mArray2 = mydb.getAllItemsAsCollection(dbName);
notifyDataSetChanged();
Toast.makeText(mContext, "Item deleted", Toast.LENGTH_SHORT).show();
}
});
// Doing for 2nd case
Item _item = getItem2(position);
String name2 = _item.name;
System.out.println(name2);
String ex = _item.expiry;
System.out.println(ex);
// For the second case
holder.itemNameView.setText(name2);
holder.itemExpiryView.setText(ex);
return convertView;
}
// this is used so you only ever have to do
// inflation and finding by ID once ever per View
private static class ViewHolder {
public TextView itemNameView;
public TextView itemExpiryView;
public Button editButton;
public Button deleteButton;
}
public void updateData2(ArrayList<Item> arrayPassed) {
// update the adapter's data set
mArray2 = arrayPassed;
notifyDataSetChanged();
}
public void setDbName(String dbName){
this.dbName = dbName;
}
}
类函数DBHelper的定义如下：
getAllItemsAsCollection()此外，public ArrayList<Item> getAllItemsAsCollection(String dbName)
{
ArrayList<Item> array_list = new ArrayList<Item>();
SQLiteDatabase db = this.getReadableDatabase();
Cursor res = db.rawQuery( "select * from " + dbName, null );
res.moveToFirst();
while(res.isAfterLast() == false){
String n = res.getString(res.getColumnIndex(COLUMN_NAME));
String e = res.getString(res.getColumnIndex(COLUMN_EXPIRY));
String c = dbName;
Item _item = new Item(n, e, c);
array_list.add(_item);
res.moveToNext();
}
return array_list;
}
内的insertItem()函数是：
DBHelper我为可自定义的对象处理添加了一个单独的类：
public boolean insertItem (String dbName, String name, String expiry)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("name", name);
contentValues.put("expiry", expiry);
db.insert(dbName, null, contentValues);
return true;
}
public class Item {
String name;
String expiry;
String category;
Item(String n, String e, String c){
this.name = n;
this.expiry = e;
this.category = c;
}
}
内的addItem()方法就像：
MainActivity.java我已正确地初始化每个变量。当我尝试运行我的应用程序并尝试添加新项目时，public void addItem(final View v) {
AlertDialog.Builder alert = new AlertDialog.Builder(MainActivity.this);
LinearLayout lila1 = new LinearLayout(this);
lila1.setOrientation(LinearLayout.VERTICAL);
final EditText name = new EditText(this);
name.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_FLAG_CAP_WORDS);
final EditText days = new EditText(this);
days.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_FLAG_CAP_WORDS);
TextView text_ex = new TextView(this);
text_ex.setText("In how many days will it expire..");
alert.setTitle("Hello!");
alert.setMessage("What did you buy today..");
lila1.addView(name);
lila1.addView(text_ex);
lila1.addView(days);
alert.setView(lila1);
// Make an "OK" button to save the name
alert.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
// Grab the EditText's input
String inputName = name.getText().toString();
String daysToExpiry = days.getText().toString();
System.out.println(daysToExpiry);
mydb.insertItem(currentDB, inputName, daysToExpiry);
System.out.println("Worked");
// For 2nd Case
currentList2 = mydb.getAllItemsAsCollection(currentDB);
System.out.println("Random Musings");
itemAdder2.updateData2(currentList2);
// addItemToList(inputName, v);
dialog.dismiss();
}
});
// Make a "Cancel" button
// that simply dismisses the alert
alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
// if this button is clicked, just close
// the dialog box and do nothing
dialog.cancel();
}
});
alert.show();
}
只是消失，并且布局中没有显示任何内容。我之前尝试过一个简单的Dialog box，它完美无缺。这就是为什么我认为ArrayList<Strings>不应该有任何问题。可能是.xml Layout函数。请帮忙。通过这些长代码感谢您的耐心。如果需要进一步的信息，请告诉我。非常感谢。 ：）
忘记为实际视图附加ListViewAdapter.updateData2()。这与.xml完美配合。我已经测试过了。当我尝试传递复杂对象时，在这种情况下，ArrayList<String>，相应地Item-class object，我的猜测是，我无法正确编写适配器部分代码。
ArrayList<Item>