我试图从数据库中检索数据,但是当我拨打showData()
时,应用程序停止。一切看起来不错,但我不知道为什么会发生。请帮助,我是Android新手。从sqlite数据库访问数据?
这属于主要活动:
public class MainActivity extends AppCompatActivity {
Button allContact,addContact,editContact,searchContact,deleteContact;
EditText name,phone;Button add;
TextView t,t2;
String dbString="";
String dbString2="";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
allContact=(Button)findViewById(R.id.button);
addContact =(Button)findViewById(R.id.button2);
editContact=(Button)findViewById(R.id.button3);
searchContact=(Button)findViewById(R.id.button4);
deleteContact =(Button)findViewById(R.id.button5);
addContact.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
setContentView(R.layout.addcontectlayout_main);
name=(EditText)findViewById(R.id.editText);
phone=(EditText)findViewById(R.id.editText2);
add=(Button)findViewById(R.id.button6);
add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String takeName=name.getText().toString().toLowerCase();
String takePhone=phone.getText().toString();
ContactDatabase onbOfContactDatabase=new ContactDatabase(getBaseContext());
onbOfContactDatabase.insertContact(takeName,takePhone);
Toast.makeText(getBaseContext(), "data is inserted", Toast.LENGTH_LONG).show();
}
});
}
});
allContact.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), AllContact.class);
startActivity(intent);
}
});
}
}
这堂课后,打算入手:
public class AllContact extends AppCompatActivity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.allcontactlayout_main);
TextView t=(TextView)findViewById(R.id.textView);
TextView t2=(TextView)findViewById(R.id.textView2);
ContactDatabase onbOfContactDatabase=new ContactDatabase(getBaseContext());
Cursor get= onbOfContactDatabase.showData();
//when i call showData application stope.
}
}
这属于数据库:
public class ContactDatabase extends SQLiteOpenHelper {
SQLiteDatabase db;
public static final String DATABASE_NAME="totalContact.db";
public static final String TABLE_NAME="contact";
public static final String NAME="name";
public static final String PHONE="phone";
public ContactDatabase(Context context) {
super(context, DATABASE_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
try {
db.execSQL("craete table contact" +
"(id integer primary key autoincrement, name text, phone text)");
}catch(android.database.SQLException e){
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS contact");
onCreate(db);
}
public void insertContact(String nam,String mob){
db=this.getWritableDatabase();
ContentValues contentValues=new ContentValues();
contentValues.put(NAME,nam);
contentValues.put(PHONE,mob);
db.insert(TABLE_NAME, null, contentValues);
db.close();
}
public Cursor showData(){
db=this.getWritableDatabase();
Cursor res = db.rawQuery("SELECT * FROM contact", null);
return res;
}
}
logcat的是:
01-06 21:51:36.282 177-177/? A/libc: invalid address or address of corrupt block 0xa2be0 passed to dlfree
06-08 21:53:00.359 11680-11680/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.firstproject.contactinfo, PID: 11680
android.database.sqlite.SQLiteException: no such table: contact (code 1): , while compiling: SELECT * FROM contact
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1316)
at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1255)
at com.example.firstproject.contactinfo.ContactDatabase.showData(ContactDatabase.java:58)
at com.example.firstproject.contactinfo.MainActivity$2.onClick(MainActivity.java:64)
at android.view.View.performClick(View.java:4761)
at android.view.View$PerformClick.run(View.java:19767)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5312)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
请编辑与**完整的** logcat你得到的错误的问题。没有它,任何人都不可能帮到你。 – Vucko
此外,为什么'onClickListener'中的'setContentView(R.layout.allcontactlayout_main);'。在**初始化任何'view'元素之前,将该行移至'onCreate'方法**。 (在'super.onCreate'之后)。 – Vucko
@Vucko setContentView(R.layout。allcontactlayout_main);因为我希望在“allcontactlayout_main”布局中显示数据库的所有元素。 –