我的Activity只显示listview（他从SQLite数据库中提取数据），他可以显示的数据没有限制，而且运行良好。
现在，我想在MainActivity中添加一个新的小列表视图，它只显示最后五个数据。
我在网络上的任何地方都找不到怎么做..
DataListActivity.java
package com.example.ido.grades;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;
public class DataListActivity extends ActionBarActivity {
ListView listView;
SQLiteDatabase sqLiteDatabase;
CourseDbHelper courseDbHelper;
Cursor cursor;
ListDataAdaptar listDataAdaptar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.update_course);
hideActionBar();
listView = (ListView) findViewById(R.id.list_view);
listDataAdaptar = new ListDataAdaptar(getApplicationContext(),R.layout.row_layout);
listView.setAdapter(listDataAdaptar);
registerForContextMenu(listView);
courseDbHelper = new CourseDbHelper(getApplicationContext());
sqLiteDatabase = courseDbHelper.getReadableDatabase();
cursor = courseDbHelper.getInformation(sqLiteDatabase);
registerForContextMenu(listView);
if (!cursor.moveToFirst()){
}
else {
do {
String year,semester,course,points,grade;
year = cursor.getString(0);
semester = cursor.getString(1);
course = cursor.getString(2);
points = cursor.getString(3);
grade = cursor.getString(4);
DataProvider dataProvider = new DataProvider(year,semester,course,points,grade);
listDataAdaptar.add(dataProvider);
}
while (cursor.moveToNext());
}
}
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_data_list, menu);
}
public boolean onContextItemSelected(MenuItem item) {
AdapterView.AdapterContextMenuInfo info =
(AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
int mySelectedRowIndex = info.position;
switch (item.getItemId()) {
case R.id.update_item:
courseDbHelper = new CourseDbHelper(getApplicationContext());
sqLiteDatabase = courseDbHelper.getReadableDatabase();
DataProvider raw2 = (DataProvider)listDataAdaptar.getItem(mySelectedRowIndex);
Intent i = new Intent(DataListActivity.this, UpdateCourseActivity.class);
String year = raw2.getYear();
String semester = raw2.getSemester();
String course = raw2.getCourse();
String points = raw2.getPoints();
String grade = raw2.getGrade();
int semIndex;
if (semester.equals("A'")){
semIndex =1;
}
else if (semester.equals("B'")){
semIndex =2;
}
else{
semIndex=3;
}
i.putExtra("YEAR", year);
i.putExtra("SEMESTER", Integer.toString(semIndex));
i.putExtra("COURSE", course);
i.putExtra("POINTS", points);
i.putExtra("GRADE", grade);
i.putExtra("POS", Integer.toString(mySelectedRowIndex));
startActivity(i);
return true;
case R.id.delete_item:
courseDbHelper = new CourseDbHelper(getApplicationContext());
sqLiteDatabase = courseDbHelper.getReadableDatabase();
DataProvider raw = (DataProvider)listDataAdaptar.getItem(mySelectedRowIndex);
courseDbHelper.deleteInformation(raw.getYear(), raw.getSemester(), raw.getCourse(), raw.getPoints(), raw.getGrade());
Toast.makeText(this,"delete, pos["+mySelectedRowIndex+"]",Toast.LENGTH_LONG).show();
finish();
startActivity(getIntent());
return true;
default:
return super.onOptionsItemSelected(item);
}
}
public void onBackPressed() {
startActivity(new Intent(this, MainActivity.class));
}
private void hideActionBar() {
//Hide the action bar only if it exists
if (getSupportActionBar() != null) {
getSupportActionBar().hide();
}
}
}
ListDataAdapter.java
package com.example.ido.grades;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
/**
* Created by Ido on 08/08/2015.
*/
public class ListDataAdaptar extends ArrayAdapter{
List list = new ArrayList();
public ListDataAdaptar(Context context, int resource) {
super(context, resource);
}
static class LayoutHandler{
TextView YEAR,SEMESTER,COURSE,POINTS,GRADE;
}
@Override
public void add(Object object) {
super.add(object);
list.add(object);
}
@Override
public int getCount() {
return list.size();
}
@Override
public Object getItem(int position) {
return list.get(position);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
LayoutHandler layoutHandler;
if (row == null){
LayoutInflater layoutInflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = layoutInflater.inflate(R.layout.row_layout,parent,false);
layoutHandler = new LayoutHandler();
layoutHandler.YEAR = (TextView)row.findViewById(R.id.textYear);
layoutHandler.SEMESTER = (TextView)row.findViewById(R.id.textSemester);
layoutHandler.COURSE = (TextView)row.findViewById(R.id.textCourse);
layoutHandler.POINTS = (TextView)row.findViewById(R.id.textPoints);
layoutHandler.GRADE = (TextView)row.findViewById(R.id.textGrade);
row.setTag(layoutHandler);
}
else{
layoutHandler = (LayoutHandler) row.getTag();
}
DataProvider dataProvider = (DataProvider) this.getItem(position);
layoutHandler.YEAR.setText(dataProvider.getYear());
layoutHandler.SEMESTER.setText(dataProvider.getSemester());
layoutHandler.COURSE.setText(dataProvider.getCourse());
layoutHandler.POINTS.setText(dataProvider.getPoints());
layoutHandler.GRADE.setText(dataProvider.getGrade());
return row;
}
}
答案 0 :(得分：1)
您可以移动到当前光标的最后一个位置，然后移动到获取所需数据的上一行。排序：
ArrayList string;
if (cursor.moveToLast()){
for (int i = 1; i<=6; i++) {
string.add(cursor.getString(cursor.getColumnIndex("your_data")));
cursor.moveToPrevious();
}
}
cursor.close();
结果将是ArrayList，其中包含游标数据的最后6个字符串。您可以将其提供给新的ArrayAdapter并在屏幕上显示它。
您可以使用所有现有数据创建另一个游标，而不是ArrayList，并将其提供给现有的适配器，例如，如下所述： https://stackoverflow.com/a/18290921/4890659
答案 1 :(得分：0)
忽略你的代码，你显然有一个对象数组传递到数组适配器的构造函数。
Object[] data = new Object[]{...}
MyArrayAdapter myAdapter = new MyArrayAdapter(data ,... else)
您只需获取此data数组，并将最后6个元素追加到新数组中。
Object[] data2 = new Object[6]
for(int i = data.length()-7; i<data.length(); i++){
data2[data.length()-i] = data[i]
然后创建一个新的适配器，传递新的data2数组。
MyArrayAdapter myAdapter = new MyArrayAdapter(data2, ... else)
答案 2 :(得分：0)
创建方法，返回光标的最后6行[SQL查询]。
public class Add_to_cart extends Fragment {
private Button continue_shopping;
private Button checkout;
ListView list;
private TextView _decrease,mBTIncrement,_value;
private CustomListAdapter adapter;
private ArrayList<String> alst;
private ArrayList<String> alstimg;
private ArrayList<String> alstprc;
private String bname;
private ArrayList<String> alsttitle;
private ArrayList<String> alsttype;
public static ArrayList<String> static_Alst;
public Add_to_cart(){}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
final View rootView = inflater.inflate(R.layout.list_view_addtocart, container, false);
alst=new ArrayList<String>();
alstimg=new ArrayList<String>();
Bundle bundle = this.getArguments();
alst = bundle.getStringArrayList("prducts_id");
alsttype = bundle.getStringArrayList("prducts_type");
alstimg=bundle.getStringArrayList("prducts_imgs");
alsttitle=bundle.getStringArrayList("prducts_title");
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
System.out.println("TEst--" + alst);
// Toast.makeText(getActivity(),"Testing"+alstimg,Toast.LENGTH_LONG).show();
list=(ListView)rootView.findViewById(R.id.list_addtocart);
adapter = new CustomListAdapter(getActivity(),alst,alstimg,alsttitle,alsttype);
list.setAdapter(adapter);
adapter.notifyDataSetChanged();
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
// TODO Auto-generated method stub
}
});
return rootView;
}
public class CustomListAdapter extends BaseAdapter {
private Context context;
private ArrayList<String> listData;
private ArrayList<String> listDataimg;
private ArrayList<String> listDatatitle;
private ArrayList<String> listDatatype;
private AQuery aQuery;
String dollars="\u0024";
public CustomListAdapter(Context context,ArrayList<String> listData,ArrayList<String> listDataimg,ArrayList<String> listDatatitle,ArrayList<String> listDatatype) {
this.context = context;
this.listData=listData;
this.listDataimg=listDataimg;
this.listDatatitle=listDatatitle;
this.listDatatype=listDatatype;
aQuery = new AQuery(this.context);
}
public void save_User_To_Shared_Prefs(Context context) {
SharedPreferences appSharedPrefs = PreferenceManager
.getDefaultSharedPreferences(context.getApplicationContext());
SharedPreferences.Editor prefsEditor = appSharedPrefs.edit();
Gson gson = new Gson();
String json = gson.toJson(listData);
Add_to_cart.static_Alst=listData;
prefsEditor.putString("user", json);
prefsEditor.commit();
}
@Override
public int getCount() {
return listData.size();
}
@Override
public Object getItem(int position) {
return listData.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
holder = new ViewHolder();
convertView = LayoutInflater.from(getActivity()).inflate(R.layout.list_item_addtocart, null);
holder.propic = (ImageView) convertView.findViewById(R.id.img_addtocart);
holder.txtproname = (TextView) convertView.findViewById(R.id.proname_addtocart);
holder.txtprofilecast = (TextView) convertView.findViewById(R.id.proprice_addtocart);
holder.txtsize = (TextView) convertView.findViewById(R.id.txt_size);
_decrease = (TextView) convertView.findViewById(R.id.minuss_addtocart);
mBTIncrement = (TextView) convertView.findViewById(R.id.plus_addtocart);
_value = (EditText)convertView.findViewById(R.id.edt_procount_addtocart);
convertView.setTag(holder);
}else{
holder = (ViewHolder) convertView.getTag();
}
mBTIncrement.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
increment();
}
});
_decrease.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
decrement();
}
});
holder.txtprofilecast.setText(dollars+listData.get(position));
holder.txtproname.setText(listDatatitle.get(position));
holder.txtsize.setText(listDatatype.get(position));
System.out.println("Image ka array " + listDataimg.get(position));
//Picasso.with(mContext).load(mThumbIds[position]).centerCrop().into(imageView);
// Picasso.with(context).load(listDataimg.get(position)).into(holder.propic);
aQuery.id(holder.propic).image(listDataimg.get(position), true, true, 0, R.drawable.ic_launcher);
return convertView;
}
class ViewHolder{
ImageView propic;
TextView txtproname;
TextView txtprofilecast;
TextView txtsize;
}
}
}
SQL：
cursor = courseDbHelper.getInformationLast_6(sqLiteDatabase);
答案 3 :(得分：0)
通过此，您可以在列表中获得6个项目。尝试使用适配器类中的以下代码。
public int getCount() {
return 6;
}
按升序或降序将查询更改为限制6 。