本文介绍了在一个ArrayAdapter无法解析构造的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我已经附加值的主题表内，但使用的ListView无法检索值了。
我的code：
DatabaseHelper.java
公共类DatabaseHelper扩展SQLiteOpenHelper {
SQLiteDatabase分贝;
公共静态最后弦乐DATABASE_NAME =myexam.db;
公共静态最终诠释DATABASE_VERSION = 1; 公共DatabaseHelper（上下文的背景下）{
超（背景下，DATABASE_NAME，空，DATABASE_VERSION）;
Log.d（数据库操作，数据库创建成功！）;
} @覆盖
公共无效的onCreate（SQLiteDatabase DB）{
字符串CREATE_USER =CREATE TABLE+
user.TABLE_USER +（+
user.USER_ID +INTEGER PRIMARY KEY NOT NULL，+
user.USER_EMAIL +VARCHAR NOT NULL，+
user.USER_PASS +VARCHAR NOT NULL，+
user.USER_CPASS +VARCHAR NOT NULL）;; 字符串CREATE_SUBJECT =CREATE TABLE+
subject.TABLE_SUBJECT +（+
subject.USER_ID +INTEGER，+
subject.SUBUSER_ID +INTEGER PRIMARY KEY NOT NULL，+
subject.SUBJECT_NAME +TEXT NOT NULL，+
subject.SUBJECT_RESULTS +TEXT NOT NULL，+
subject.SUBJECT_HOURS +TEXT NOT NULL）;; db.execSQL（CREATE_USER）;
db.execSQL（CREATE_SUBJECT）;
Log.d（数据库操作，表创建！）;
} @覆盖
公共无效onUpgrade（SQLiteDatabase分贝，INT oldVersion，诠释静态网页）{
db.execSQL（DROP TABLE IF EXISTS+ user.TABLE_USER）;
db.execSQL（DROP TABLE IF EXISTS+ subject.TABLE_SUBJECT）;
的onCreate（DB）;
} //插入用户
公共布尔insertUser（UID字符串，字符串电子邮件，字符串传递，字符串cpass）{
SQLiteDatabase分贝= this.getWritableDatabase（）; ContentValues CV =新ContentValues（）; cv.put（user.USER_ID，UID）;
cv.put（user.USER_EMAIL，电子邮件）;
cv.put（user.USER_PASS，通过）;
cv.put（user.USER_CPASS，cpass）;
长USER_ID = db.insert（user.TABLE_USER，空，CV）; 如果（USER_ID == -1）{
返回false;
}其他
返回true;
} //获取用户
公共光标的getUser（）{
SQLiteDatabase分贝= this.getReadableDatabase（）;
串selectQuery =SELECT+ user.USER_ID +，+ user.USER_PASS +从+ user.TABLE_USER; 光标C = db.rawQuery（selectQuery，NULL）; 返回℃;
} //插入主题
公共布尔insertSubjects（UID字符串，字符串SNAME，字符串sresults，字符串shours）{
SQLiteDatabase分贝= this.getWritableDatabase（）; ContentValues CV =新ContentValues（）; cv.put（subject.SUBUSER_ID，UID）;
cv.put（subject.SUBJECT_NAME，SNAME）;
cv.put（subject.SUBJECT_RESULTS，sresults）;
cv.put（subject.SUBJECT_HOURS，shours）;
长sub_id = db.insert（subject.TABLE_SUBJECT，空，CV）; 如果（sub_id == -1）{
返回false;
}其他
返回true;
} 公共光标getSubjects（）{
SQLiteDatabase分贝= this.getReadableDatabase（）;
串selectQuery =SELECT+ subject.SUBUSER_ID +
，+ subject.SUBJECT_NAME +
，+ subject.SUBJECT_RESULTS +
，+ subject.SUBJECT_HOURS +
FROM+ subject.TABLE_SUBJECT +
WHERE+ subject.SUBUSER_ID +
=+ subject.USER_ID; 光标C = db.rawQuery（selectQuery，NULL）;
返回℃;
}
}
subject.java
公共类主题{
公共静态最后弦乐SUBUSER_ID =etUID;
公共静态最后弦乐USER_ID = user.USER_ID;
公共静态最后弦乐SUBJECT_NAME =etSubjects;
公共静态最后弦乐SUBJECT_RESULTS =etResults;
公共静态最后弦乐SUBJECT_HOURS =etHours;
公共静态最后弦乐TABLE_SUBJECT =科目;
}
user.java
公共类用户{
公共静态最后弦乐USER_ID =ETID;
公共静态最后弦乐USER_EMAIL =etEmail;
公共静态最后弦乐USER_PASS =etPassword;
公共静态最后弦乐USER_CPASS =etCPassword;
公共静态最后弦乐TABLE_USER =用户;
}
addSubject.java
公共类addSubjects扩展AppCompatActivity { 的EditText etUID，etSubjects，etResults，etHours;
DatabaseHelper databaseHelper; @覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.activity_add_subjects）; etUID =（EditText上）findViewById（R.id.etUID）;
etSubjects =（EditText上）findViewById（R.id.etSubjects）;
etResults =（EditText上）findViewById（R.id.etResults）;
etHours =（EditText上）findViewById（R.id.etHours）; databaseHelper =新DatabaseHelper（本）; 动作条动作条= getSupportActionBar（）;
actionBar.setHomeButtonEnabled（真）;
actionBar.setDisplayHomeAsUpEnabled（真）;
} @覆盖
公共布尔onCreateOptionsMenu（菜单菜单）{
//充气菜单;如果是present这增加了项目操作栏。
。getMenuInflater（）膨胀（R.menu.menu_add_subjects，菜单）;
返回true;
} @覆盖
公共布尔onOptionsItemSelected（菜单项项）{
//处理动作栏项目点击这里。操作栏会
//自动处理上点击主页/向上按钮，只要
//你在AndroidManifest.xml中指定一个父活动。
INT ID = item.getItemId（）; 如果（ID == android.R.id.home）{
意图I =新意图（这一点，subjects.class）;
startActivity（ⅰ）;
完（）;
} // noinspection SimplifiableIfStatement
如果（ID == R.id.action_home）{
意图I =新意图（这一点，Menus.class）;
startActivity（ⅰ）;
完（）;
}
返回super.onOptionsItemSelected（项目）;
} 公共无效SaveInfo（查看视图）{
。字符串userid = etUID.getText（）的toString（）;
字符串对象= etSubjects.getText（）的toString（）。
字符串结果= etResults.getText（）的toString（）。
串个小时= etHours.getText（）的toString（）。 如果（userid.equals（）|| subjects.equals（）|| results.equals（）|| hours.equals（））{
Toast.makeText（addSubjects.this，请在所有的关键信息，Toast.LENGTH_SHORT）.show（）;
}
否则如果（（results.equals（A））及！及（results.equals（B））及！及（results.equals（C））及！及（！ results.equals（D））及及（！results.equals（F）））{
Toast.makeText（getBaseContext（），请键入有效的结果！Toast.LENGTH_SHORT）.show（）;
}
否则如果（（hours.equals（1））及！及（hours.equals（二））及！及（hours.equals（三公））及！及（！ hours.equals（四）））{
Toast.makeText（getBaseContext（），请键入有效的小时！，Toast.LENGTH_SHORT）.show（）;
}
其他{
布尔isInserted = databaseHelper.insertSubjects（用户ID，受试者，结果，小时）;
如果（isInserted = TRUE）{
Toast.makeText（addSubjects.this，补充说：成功！，Toast.LENGTH_SHORT）.show（）;
意图I =新意图（这一点，subjects.class）;
startActivity（ⅰ）;
完（）;
}其他{
Toast.makeText（addSubjects.this，不成功补充!!!，Toast.LENGTH_SHORT）.show（）;
}
}
}
}
subject.java （的ListView ）
包com.smartexamorganizer.subjects;进口android.content.Intent;
进口android.database.Cursor;
进口android.os.Bundle;
进口android.support.v7.app.AppCompatActivity;
进口android.view.Menu;
进口android.view.MenuItem;
进口android.widget.ListView;进口com.smartexamorganizer.ListData.ListDataAdapter;
进口com.smartexamorganizer.ListData.SubjectProvider;
进口com.smartexamorganizer.R;
进口com.smartexamorganizer.activity.Menus;
进口com.smartexamorganizer.database.DatabaseHelper;公共类科目扩展AppCompatActivity { ListView的lvSubjects; DatabaseHelper databaseHelper;
光标光标;
ListDataAdapter listDataAdapter; @覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.activity_subjects）; lvSubjects =（ListView控件）findViewById（R.id.lvSubjects）; listDataAdapter =新ListDataAdapter（getApplicationContext（），R.layout.display_subjects_row）;
lvSubjects.setAdapter（listDataAdapter）; databaseHelper =新DatabaseHelper（本）;
databaseHelper.getReadableDatabase（）;
光标= databaseHelper.getSubjects（）; 如果（cursor.moveToFirst（））{
做{
串sub_name，sub_results，sub_hours;
sub_name = cursor.getString（0）;
sub_results = cursor.getString（1）;
sub_hours = cursor.getString（2）; SubjectProvider subjectProvider =新SubjectProvider名（sub_name，sub_results，sub_hours）;
listDataAdapter.add（subjectProvider）; //传递数据的每一行 }而（cursor.moveToNext（））;
}
} @覆盖
公共布尔onCreateOptionsMenu（菜单菜单）{
//充气菜单;如果是present这增加了项目操作栏。
。getMenuInflater（）膨胀（R.menu.menu_subjects，菜单）;
返回true;
} @覆盖
公共布尔onOptionsItemSelected（菜单项项）{
//处理动作栏项目点击这里。操作栏会
//自动处理上点击主页/向上按钮，只要
//你在AndroidManifest.xml中指定一个父活动。
INT ID = item.getItemId（）; // noinspection SimplifiableIfStatement
如果（ID == R.id.action_add）{
意图I =新意图（这一点，addSubjects.class）;
startActivity（ⅰ）;
完（）;
} 如果（ID == R.id.action_home）{
意图I =新意图（这一点，Menus.class）;
startActivity（ⅰ）;
完（）;
} 返回super.onOptionsItemSelected（项目）;
}
}
ListDataAdapter.java
包com.smartexamorganizer.ListData;进口android.content.Context;
进口android.view.LayoutInflater;
进口android.view.View;
进口android.view.ViewGroup;
进口android.widget.ArrayAdapter;
进口android.widget.TextView;进口com.smartexamorganizer.R;进口的java.util.ArrayList;
进口的java.util.List;/ **
*创建宏碁在2015年12月18日。
* /
公共类ListDataAdapter扩展ArrayAdapter {
列表列表=新的ArrayList（）;
公共ListDataAdapter（上下文的背景下，资源INT）{
超（背景下，资源）;
} 静态类LayoutHandler {
TextView的SUB_NAME，SUB_RESULTS，SUB_HOURS;
}
@覆盖
公共无效添加（Object对象）{
super.add（对象）;
list.add（对象）;
} @覆盖
公众诠释的getCount（）{
返回则为list.size（）;
} @覆盖
公共对象的getItem（INT位置）{
返回list.get（位置）;
} @覆盖
公共查看getView（INT位置，查看convertView，父母的ViewGroup）{
查看排= convertView;
LayoutHandler layoutHandler;
如果（行== NULL）{
LayoutInflater layoutInflater =（LayoutInflater）this.getContext（）getSystemService（Context.LAYOUT_INFLATER_SERVICE）。
行= layoutInflater.inflate（R.layout.display_subjects_row，父母，假）;
layoutHandler =新LayoutHandler（）;
layoutHandler.SUB_NAME =（TextView中）row.findViewById（R.id.tvSub_Name）;
layoutHandler.SUB_RESULTS =（TextView中）row.findViewById（R.id.tvSub_Results）;
layoutHandler.SUB_HOURS =（TextView中）row.findViewById（R.id.tvSub_Hours）;
row.setTag（layoutHandler）;
}
其他{
layoutHandler =（LayoutHandler）row.getTag（）;
}
SubjectProvider subjectProvider =（SubjectProvider）this.getItem（位置）;
layoutHandler.SUB_NAME.setText（subjectProvider.getSub_name（））;
layoutHandler.SUB_RESULTS.setText（subjectProvider.getSub_results（））;
layoutHandler.SUB_HOURS.setText（subjectProvider.getSub_hours（））; 返回行;
}
}
SubjectProvider.java
公共类SubjectProvider {
私人字符串sub_name;
私人字符串sub_results;
私人字符串sub_hours; 公共SubjectProvider（字符串sub_name，字符串sub_results，字符串sub_hours）{
this.sub_name = sub_name;
this.sub_results = sub_results;
this.sub_hours = sub_hours;
} 公共字符串getSub_hours（）{
返回sub_hours;
} 公共无效setSub_hours（字符串sub_hours）{
this.sub_hours = sub_hours;
} 公共字符串getSub_name（）{
返回sub_name;
} 公共无效setSub_name（字符串sub_name）调用{
this.sub_name = sub_name;
} 公共字符串getSub_results（）{
返回sub_results;
} 公共无效setSub_results（字符串sub_results）{
this.sub_results = sub_results;
}
}
错误：
错误：（40 45）错误：发现ArrayAdapter没有合适的构造（科目，INT，ArrayList的＆LT; SubjectProvider＆GT;）
构造ArrayAdapter.ArrayAdapter（背景下，INT，INT）不适用
（参数不匹配; ArrayList的＆LT; SubjectProvider＆GT;不能被转换成int）
构造ArrayAdapter.ArrayAdapter（背景下，INT的String []）不适用
（参数不匹配; ArrayList的＆LT; SubjectProvider每个可不能转换为字符串[]）
构造ArrayAdapter.ArrayAdapter（背景下，INT，列表与LT;弦乐＆gt;）的不适用
（参数不匹配; ArrayList的＆LT; SubjectProvider每个可不能转换为List＆LT;串GT;）
解决方案
试试这个：
// getSubjects（）现在将返回SubjectProviders的List
//你可以看到下面的
公众的ArrayList＆LT; SubjectProvider＆GT; getSubjects（）{
//获取数据库
SQLiteDatabase分贝= this.getReadableDatabase（）;
//创建一个应该返回名称的结果和时间查询
//对于具有subuser_id等于USER_ID各受试者
串selectQuery =SELECT+ subject.SUBJECT_NAME +
，+ subject.SUBJECT_RESULTS +
，+ subject.SUBJECT_HOURS +
FROM+ subject.TABLE_SUBJECT +
WHERE+ subject.SUBUSER_ID +
=+ subject.USER_ID; //创建中，我们会迟到存储所有subjectproviders ArrayList中
//此ArrayList将被退回，所以你可以在你的类科目使用
ArrayList的＆LT; SubjectProvider＆GT; subjectList =新的ArrayList＆LT; SubjectProvider＆GT;（）
//执行选择查询
光标C = db.rawQuery（selectQuery，NULL）;
//如果光标不为空，又名一些至少有一行被发现
如果（c.moveToFirst（））{
//通过所有的循环结果
做{
的System.out.println（发现结果！）;
//从游标获取值
串sub_name，sub_results，sub_hours;
sub_name = cursor.getString（0）;
sub_results = cursor.getString（1）;
sub_hours = cursor.getString（2）; //创建一个新subjectprovider对象来存储它的价值观
SubjectProvider subjectProvider =新SubjectProvider名（sub_name，sub_results，sub_hours）; 的System.out.println（主题：+ sub_name +中的+ sub_hours得到+ sub_results +）;
//它添加到ArrayList
subjectList.add（subjectProvider）;
//停止，如果没有更多的结果
}而（c.moveToNext（））;
}
//列表回到你的主题类
返回subjectList;
}
和科目：
//创建一个新的ArrayList中，将包含值从
// getsubjects方法 ArrayList的＆LT; SubjectProvider＆GT; my_array_list =（ArrayList的＆LT; SubjectProvider＆GT;）databaseHelper.getSubjects（）;
//创建一个适配器，以便可以从ArrayList中添加值到你的列表视图
ArrayAdapter＆LT;串GT; arrayAdapter =新ArrayAdapter＆LT;串GT;（
subjects.this，
android.R.layout.simple_list_item_1，
my_array_list）; //设置previously创建适配器为您的列表视图适配器
lvSubjects.setAdapter（arrayAdapter）;
插入方式：
//插入主题
公共布尔insertSubjects（整数ID，UID整数，字符串SNAME，字符串sresults，字符串shours）{
SQLiteDatabase分贝= this.getWritableDatabase（）; ContentValues CV =新ContentValues（）; cv.put（user.USER_ID，身份证）;
cv.put（subject.SUBUSER_ID，UID）;
cv.put（subject.SUBJECT_NAME，SNAME）;
cv.put（subject.SUBJECT_RESULTS，sresults）;
cv.put（subject.SUBJECT_HOURS，shours）;
长sub_id = db.insert（subject.TABLE_SUBJECT，空，CV）; 如果（sub_id == -1）{
返回false;
}其他
返回true;
}
}
I had added values inside the subjects table but could not retrieve the values out using ListView.
My code:
DatabaseHelper.java
public class DatabaseHelper extends SQLiteOpenHelper {
SQLiteDatabase db;
public static final String DATABASE_NAME = "myexam.db";
public static final int DATABASE_VERSION = 1;
public DatabaseHelper(Context context) {
super(context,DATABASE_NAME, null, DATABASE_VERSION);
Log.d("Database operations", "Database successfully created!");
}
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_USER = "CREATE TABLE " +
user.TABLE_USER + "(" +
user.USER_ID + " INTEGER PRIMARY KEY NOT NULL," +
user.USER_EMAIL + " VARCHAR NOT NULL," +
user.USER_PASS + " VARCHAR NOT NULL," +
user.USER_CPASS + " VARCHAR NOT NULL);";
String CREATE_SUBJECT = "CREATE TABLE " +
subject.TABLE_SUBJECT + "(" +
subject.USER_ID + " INTEGER," +
subject.SUBUSER_ID + " INTEGER PRIMARY KEY NOT NULL," +
subject.SUBJECT_NAME + " TEXT NOT NULL," +
subject.SUBJECT_RESULTS + " TEXT NOT NULL," +
subject.SUBJECT_HOURS + " TEXT NOT NULL);";
db.execSQL(CREATE_USER);
db.execSQL(CREATE_SUBJECT);
Log.d("Database operations", "Table created!");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + user.TABLE_USER);
db.execSQL("DROP TABLE IF EXISTS " + subject.TABLE_SUBJECT);
onCreate(db);
}
//insert User
public boolean insertUser(String uid, String email, String pass, String cpass) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(user.USER_ID, uid);
cv.put(user.USER_EMAIL, email);
cv.put(user.USER_PASS, pass);
cv.put(user.USER_CPASS, cpass);
long user_id = db.insert(user.TABLE_USER, null, cv);
if (user_id == -1){
return false;
}else
return true;
}
//get User
public Cursor getUser(){
SQLiteDatabase db = this.getReadableDatabase();
String selectQuery = "SELECT "+ user.USER_ID + ", " + user.USER_PASS + " FROM " + user.TABLE_USER;
Cursor c = db.rawQuery(selectQuery, null);
return c;
}
//insert Subjects
public boolean insertSubjects(String uid, String sname, String sresults, String shours) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(subject.SUBUSER_ID, uid);
cv.put(subject.SUBJECT_NAME, sname);
cv.put(subject.SUBJECT_RESULTS, sresults);
cv.put(subject.SUBJECT_HOURS, shours);
long sub_id = db.insert(subject.TABLE_SUBJECT, null, cv);
if (sub_id == -1){
return false;
}else
return true;
}
public Cursor getSubjects(){
SQLiteDatabase db = this.getReadableDatabase();
String selectQuery = "SELECT "+ subject.SUBUSER_ID +
", " + subject.SUBJECT_NAME +
", " + subject.SUBJECT_RESULTS +
", " + subject.SUBJECT_HOURS +
" FROM " + subject.TABLE_SUBJECT +
" WHERE " + subject.SUBUSER_ID +
" = " + subject.USER_ID;
Cursor c = db.rawQuery(selectQuery, null);
return c;
}
}
subject.java
public class subject {
public static final String SUBUSER_ID = "etUID";
public static final String USER_ID = user.USER_ID;
public static final String SUBJECT_NAME = "etSubjects";
public static final String SUBJECT_RESULTS = "etResults";
public static final String SUBJECT_HOURS = "etHours";
public static final String TABLE_SUBJECT = "subjects";
}
user.java
public class user {
public static final String USER_ID = "etID";
public static final String USER_EMAIL = "etEmail";
public static final String USER_PASS = "etPassword";
public static final String USER_CPASS = "etCPassword";
public static final String TABLE_USER = "user";
}
addSubject.java
public class addSubjects extends AppCompatActivity {
EditText etUID, etSubjects, etResults, etHours;
DatabaseHelper databaseHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_subjects);
etUID = (EditText)findViewById(R.id.etUID);
etSubjects = (EditText)findViewById(R.id.etSubjects);
etResults = (EditText)findViewById(R.id.etResults);
etHours = (EditText)findViewById(R.id.etHours);
databaseHelper = new DatabaseHelper(this);
ActionBar actionBar = getSupportActionBar();
actionBar.setHomeButtonEnabled(true);
actionBar.setDisplayHomeAsUpEnabled(true);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_add_subjects, menu);
return true;
}
@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 == android.R.id.home){
Intent i = new Intent(this, subjects.class);
startActivity(i);
finish();
}
//noinspection SimplifiableIfStatement
if (id == R.id.action_home) {
Intent i = new Intent(this, Menus.class);
startActivity(i);
finish();
}
return super.onOptionsItemSelected(item);
}
public void SaveInfo(View view){
String userid = etUID.getText().toString();
String subjects = etSubjects.getText().toString();
String results = etResults.getText().toString();
String hours = etHours.getText().toString();
if(userid.equals("") || subjects.equals("") || results.equals("") || hours.equals("")){
Toast.makeText(addSubjects.this, "Please key in all the information", Toast.LENGTH_SHORT).show();
}
else if((!results.equals("A")) && (!results.equals("B")) && (!results.equals("C")) && (!results.equals("D")) && (!results.equals("F"))){
Toast.makeText(getBaseContext(), "Please key in valid results!", Toast.LENGTH_SHORT).show();
}
else if((!hours.equals("One")) && (!hours.equals("Two")) && (!hours.equals("Three")) && (!hours.equals("Four"))){
Toast.makeText(getBaseContext(), "Please key in valid hours!", Toast.LENGTH_SHORT).show();
}
else{
boolean isInserted = databaseHelper.insertSubjects(userid, subjects, results, hours);
if(isInserted = true){
Toast.makeText(addSubjects.this, "Added Successfully!!!", Toast.LENGTH_SHORT).show();
Intent i = new Intent(this, subjects.class);
startActivity(i);
finish();
}else{
Toast.makeText(addSubjects.this, "Unsuccessfully added!!!", Toast.LENGTH_SHORT).show();
}
}
}
}
subject.java (ListView)
package com.smartexamorganizer.subjects;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;
import com.smartexamorganizer.ListData.ListDataAdapter;
import com.smartexamorganizer.ListData.SubjectProvider;
import com.smartexamorganizer.R;
import com.smartexamorganizer.activity.Menus;
import com.smartexamorganizer.database.DatabaseHelper;
public class subjects extends AppCompatActivity {
ListView lvSubjects;
DatabaseHelper databaseHelper;
Cursor cursor;
ListDataAdapter listDataAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_subjects);
lvSubjects = (ListView) findViewById(R.id.lvSubjects);
listDataAdapter = new ListDataAdapter(getApplicationContext(), R.layout.display_subjects_row);
lvSubjects.setAdapter(listDataAdapter);
databaseHelper = new DatabaseHelper(this);
databaseHelper.getReadableDatabase();
cursor = databaseHelper.getSubjects();
if (cursor.moveToFirst()) {
do {
String sub_name, sub_results, sub_hours;
sub_name = cursor.getString(0);
sub_results = cursor.getString(1);
sub_hours = cursor.getString(2);
SubjectProvider subjectProvider = new SubjectProvider(sub_name, sub_results, sub_hours);
listDataAdapter.add(subjectProvider); //pass each row of data
} while (cursor.moveToNext());
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_subjects, menu);
return true;
}
@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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_add) {
Intent i = new Intent(this, addSubjects.class);
startActivity(i);
finish();
}
if (id == R.id.action_home) {
Intent i = new Intent(this, Menus.class);
startActivity(i);
finish();
}
return super.onOptionsItemSelected(item);
}
}
ListDataAdapter.java
package com.smartexamorganizer.ListData;
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 com.smartexamorganizer.R;
import java.util.ArrayList;
import java.util.List;
/**
* Created by Acer on 12/18/2015.
*/
public class ListDataAdapter extends ArrayAdapter {
List list = new ArrayList();
public ListDataAdapter(Context context, int resource) {
super(context, resource);
}
static class LayoutHandler{
TextView SUB_NAME, SUB_RESULTS, SUB_HOURS;
}
@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.display_subjects_row, parent, false);
layoutHandler = new LayoutHandler();
layoutHandler.SUB_NAME = (TextView)row.findViewById(R.id.tvSub_Name);
layoutHandler.SUB_RESULTS = (TextView)row.findViewById(R.id.tvSub_Results);
layoutHandler.SUB_HOURS = (TextView)row.findViewById(R.id.tvSub_Hours);
row.setTag(layoutHandler);
}
else{
layoutHandler = (LayoutHandler)row.getTag();
}
SubjectProvider subjectProvider = (SubjectProvider) this.getItem(position);
layoutHandler.SUB_NAME.setText(subjectProvider.getSub_name());
layoutHandler.SUB_RESULTS.setText(subjectProvider.getSub_results());
layoutHandler.SUB_HOURS.setText(subjectProvider.getSub_hours());
return row;
}
}
SubjectProvider.java
public class SubjectProvider {
private String sub_name;
private String sub_results;
private String sub_hours;
public SubjectProvider(String sub_name, String sub_results, String sub_hours){
this.sub_name = sub_name;
this.sub_results = sub_results;
this.sub_hours = sub_hours;
}
public String getSub_hours() {
return sub_hours;
}
public void setSub_hours(String sub_hours) {
this.sub_hours = sub_hours;
}
public String getSub_name() {
return sub_name;
}
public void setSub_name(String sub_name) {
this.sub_name = sub_name;
}
public String getSub_results() {
return sub_results;
}
public void setSub_results(String sub_results) {
this.sub_results = sub_results;
}
}
Error:
Error:(40, 45) error: no suitable constructor found for ArrayAdapter(subjects,int,ArrayList<SubjectProvider>)
constructor ArrayAdapter.ArrayAdapter(Context,int,int) is not applicable
(argument mismatch; ArrayList<SubjectProvider> cannot be converted to int)
constructor ArrayAdapter.ArrayAdapter(Context,int,String[]) is not applicable
(argument mismatch; ArrayList<SubjectProvider> cannot be converted to String[])
constructor ArrayAdapter.ArrayAdapter(Context,int,List<String>) is not applicable
(argument mismatch; ArrayList<SubjectProvider> cannot be converted to List<String>)
解决方案
Try this:
// getSubjects() will now return a List of SubjectProviders
// as you can see below
public ArrayList<SubjectProvider> getSubjects(){
// obtain the database
SQLiteDatabase db = this.getReadableDatabase();
// create the query that should return name results and hours
// for each subject that has the subuser_id equal to the user_id
String selectQuery = "SELECT " + subject.SUBJECT_NAME +
", " + subject.SUBJECT_RESULTS +
", " + subject.SUBJECT_HOURS +
" FROM " + subject.TABLE_SUBJECT +
" WHERE " + subject.SUBUSER_ID +
" = " + subject.USER_ID;
// create the arraylist in which we will late store all the subjectproviders
// this arraylist will be returned so you can use it in your subjects class
ArrayList<SubjectProvider> subjectList = new ArrayList<SubjectProvider>()
// execute the select-query
Cursor c = db.rawQuery(selectQuery, null);
// if the cursor is not empty aka some at least one row was found
if (c.moveToFirst()) {
// loop through all the results
do {
System.out.println("Results were found!");
// get the values from the cursor
String sub_name, sub_results, sub_hours;
sub_name = cursor.getString(0);
sub_results = cursor.getString(1);
sub_hours = cursor.getString(2);
// create a new subjectprovider Object to store the values in it
SubjectProvider subjectProvider = new SubjectProvider(sub_name, sub_results, sub_hours);
System.out.println("Subject: "+sub_name+" got" +sub_results+" in "+sub_hours);
// add it to the arraylist
subjectList.add(subjectProvider);
// stop if there are no more results
} while (c.moveToNext());
}
// return the list to your subjects class
return subjectList;
}
and in subjects:
// create a new arraylist, that will contain the values from your
// getsubjects method
ArrayList<SubjectProvider> my_array_list = (ArrayList<SubjectProvider>) databaseHelper.getSubjects();
// create an adapter so you can add the values from the arraylist to your listview
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(
subjects.this,
android.R.layout.simple_list_item_1,
my_array_list);
// set the previously created adapter as an adapter for your listview
lvSubjects.setAdapter(arrayAdapter);
Insert method:
//insert Subjects
public boolean insertSubjects(Integer id, Integer uid, String sname, String sresults, String shours) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(user.USER_ID, id);
cv.put(subject.SUBUSER_ID, uid);
cv.put(subject.SUBJECT_NAME, sname);
cv.put(subject.SUBJECT_RESULTS, sresults);
cv.put(subject.SUBJECT_HOURS, shours);
long sub_id = db.insert(subject.TABLE_SUBJECT, null, cv);
if (sub_id == -1){
return false;
}else
return true;
}
}
这篇关于在一个ArrayAdapter无法解析构造的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！