当我试图在卡片视图中显示联系人时，我点击按钮它显示致命异常错误它不显示cardview任何人都可以用brillliance解决这个编程而另一个错误是当我再次点击时它只显示一个cardview应用程序将被打击？
Showcontacts.java
public class ShowContacts extends Activity
{
private SQLiteDatabase db;
DbOperations doo;
private List<Contacts> contactsList;
private RecyclerView rv;
private Cursor c;
String names,email,address;
int phone;
String read_query = "select * from"+ ContactsTask.ContactsEntry.TABLE_NAME;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.recycle_layout);
doo = new DbOperations(this);
openDatabase();
rv = (RecyclerView)findViewById(R.id.recyclerview);
initializeData();
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
rv.setLayoutManager(linearLayoutManager);
rv.setHasFixedSize(true);
ContactAdapter cc = new ContactAdapter(contactsList);
rv.setAdapter(cc);
}
public void initializeData() {
contactsList = new ArrayList<>();
c = db.rawQuery(read_query,null);
c.moveToFirst();
while (!c.isLast())
{
names = c.getString(0);
phone = c.getInt(1);
email = c.getString(2);
address = c.getString(3);
contactsList.add(new Contacts(names,phone,email,address));
}
c.isLast();
names = c.getString(0);
phone = c.getInt(1);
email = c.getString(2);
address = c.getString(3);
contactsList.add(new Contacts(names,phone,email,address));
}
private void openDatabase() {
db = openOrCreateDatabase("contactDB", Context.MODE_PRIVATE,null);
}
}
Logacat错误
06-28 08:57:43.107 568-568/com.example.anilkumar.contactstask E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.anilkumar.contactstask/com.example.anilkumar.contactstask.ShowContacts}: android.database.sqlite.SQLiteException: near "fromcontacts": syntax error: , while compiling: select * fromcontacts
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
at android.app.ActivityThread.access$600(ActivityThread.java:123)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4424)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.database.sqlite.SQLiteException: near "fromcontacts": syntax error: , while compiling: select * fromcontacts
at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:68)
at android.database.sqlite.SQLiteProgram.compileSql(SQLiteProgram.java:143)
at android.database.sqlite.SQLiteProgram.compileAndbindAllArgs(SQLiteProgram.java:361)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:127)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:94)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:53)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1564)
at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1538)
at com.example.anilkumar.contactstask.ShowContacts.initializeData(ShowContacts.java:44)
at com.example.anilkumar.contactstask.ShowContacts.onCreate(ShowContacts.java:34)
at android.app.Activity.performCreate(Activity.java:4466)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
at android.app.ActivityThread.access$600(ActivityThread.java:123)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4424)
at java.lang.reflect.Method.invokeNative(Native Method)
另一个logact错误
06-28 13:14:40.552 11252-11261/com.example.anilkumar.contactstask E/SQLiteDatabase: close() was never explicitly called on database '/data/data/com.example.anilkumar.contactstask/databases/contactDB'
android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the cursor or database object that was opened here
at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1943)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:1007)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:986)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:962)
at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:1043)
at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:1036)
at android.app.ContextImpl.openOrCreateDatabase(ContextImpl.java:761)
at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:215)
at com.example.anilkumar.contactstask.ShowContacts.openDatabase(ShowContacts.java:66)
at com.example.anilkumar.contactstask.ShowContacts.onCreate(ShowContacts.java:33)
at android.app.Activity.performCreate(Activity.java:4466)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
at android.app.ActivityThread.access$600(ActivityThread.java:123)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4424)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
答案 0 :(得分：1)
只需更新
String read_query = "select * from"+ ContactsTask.ContactsEntry.TABLE_NAME;
到
String read_query = "select * from "+ ContactsTask.ContactsEntry.TABLE_NAME;
始终关闭光标。更新你的initializeData方法
public void initializeData() {
try {
contactsList = new ArrayList<>();
try{
c = db.rawQuery(read_query,null);
c.moveToFirst();
while (!c.isLast())
{
names = c.getString(0);
phone = c.getInt(1);
email = c.getString(2);
address = c.getString(3);
contactsList.add(new Contacts(names,phone,email,address));
}
c.isLast();
names = c.getString(0);
phone = c.getInt(1);
email = c.getString(2);
address = c.getString(3);
contactsList.add(new Contacts(names,phone,email,address));
} catch (Exception e) {
// exception handling
} finally {
if(c != null){
c.close();
}
}
}