In my MainActivity I want my button to delete all items in my view list. Unfortunately, all the solutions I found here won't help me. If I click on the Button "Clear All" it deletes every item in my list, but the items are still saved in my Database.
I am totally new to Android Studio, so I don´t know how to write my code that it will work the way I want it.
This is my MainActivity:
package com.vorlesung.iubh.todo;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.SparseBooleanArray;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
DatabaseHepler myDB;
ArrayList<String> list;
ListView myToDoList;
ArrayAdapter<String> arrayAdapter;
SparseBooleanArray selectedItem;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button addToDo = (Button) findViewById(R.id.addToDo);
Button clearAll = (Button) findViewById(R.id.clearALL);
Button editSelected = (Button) findViewById(R.id.editSelected);
Button clearDone = (Button) findViewById(R.id.clearDone);
myToDoList = (ListView) findViewById(R.id.myToDoList);
myDB = new DatabaseHepler(this);
list = new ArrayList<>();
Cursor data = myDB.getListContents();
if (data.getCount() == 0)
Toast.makeText(this, "The Database was empty", Toast.LENGTH_LONG).show();
else {
while (data.moveToNext()) {
list.add(data.getString(1));
arrayAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_multiple_choice, list);
myToDoList.setAdapter(arrayAdapter);
}
}
}
public void onClickaddToDo(View button) {
Intent newToDo = new Intent(this, AddToDo.class);
startActivity(newToDo);
}
// With this onClick I want to delete all Items from my List.
public void onClickaclearALL(View button) {
list.clear();
arrayAdapter.notifyDataSetChanged();
}
}
And this is my DataBase:
package com.vorlesung.iubh.todo;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHepler extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "myList.db";
public static final String TABLE_NAME = "myList_Data";
public static final String COL1 = "ID";
public static final String COL2 = "ITEM1";
public DatabaseHepler(Context context){super(context, DATABASE_NAME, null, 1);}
@Override
public void onCreate(SQLiteDatabase db) {
String createTable = "CREATE TABLE " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, " + "ITEM1 TEXT)";
db.execSQL(createTable);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
db.execSQL("DROP IF TABLE EXISTS " + TABLE_NAME);
}
public boolean addData(String item1) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL2, item1);
long result = db.insert(TABLE_NAME, null, contentValues);
if(result == -1) {
return false;
} else {
return true;
}
}
public Cursor getListContents() {
SQLiteDatabase db = this.getWritableDatabase();
Cursor data = db.rawQuery("SELECT * FROM " + TABLE_NAME, null);
return data;
}
public void deleteRow() {
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("DELETE FROM " + TABLE_NAME+ " WHERE "+ COL2, null);
db.close();
}
}
There are the errors which are shown in my log File:
2018-12-23 10:16:05.627 21957-21973/com.vorlesung.iubh.todo E/eglCodecCommon: glUtilsParamSize: unknow param 0x000082da
2018-12-23 10:16:05.627 21957-21973/com.vorlesung.iubh.todo E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008cdf
2018-12-23 10:16:05.628 21957-21973/com.vorlesung.iubh.todo E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008824
2018-12-23 10:17:26.766 21957-21957/com.vorlesung.iubh.todo E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.vorlesung.iubh.todo, PID: 21957
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:390)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.IllegalArgumentException: Empty bindArgs
at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1656)
at com.vorlesung.iubh.todo.DatabaseHepler.deleteAllRow(DatabaseHepler.java:51)
at com.vorlesung.iubh.todo.MainActivity.onClickaclearALL(MainActivity.java:59)
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
You need to create a function in DatabaseHepler, to delete all the elements from table.
In DatabaseHepler class Need to write this function.
public void deleteAllRow() {
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("delete from "+ TABLE_NAME);
db.close();
}
In your main activity need to write this code:
// With this onClick I want to delete all Items from my List.
public void onClickaclearALL(View button) {
list.clear();
myDB.deleteAllRow(); // this will delete all data from the table.
arrayAdapter.notifyDataSetChanged();
}
This will help for you.