Question

View Database XML file:

     <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" 
android:background="@drawable/wood_bg" >

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:layout_marginBottom="10dp"
    android:layout_marginTop="10dp"
    android:text="Daily Fruit Log"
    android:textAppearance="?android:attr/textAppearanceLarge" 
    android:textStyle="bold"/>


<TableLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" >

    <TableRow>

    <TextView
        android:layout_width="110dp"
        android:layout_height="fill_parent"
        android:text="Name of fruit" 
        android:layout_weight="1"
        android:textStyle="bold"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:text="No Of Fruit" 
        android:layout_weight="1"
        android:textStyle="bold"/>

     <TextView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:text="Total Calories" 
        android:layout_weight="1"
        android:textStyle="bold"/>

    </TableRow>
    </TableLayout>

<TableLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="10dp">

    <TableRow>

    <TextView
    android:id="@+id/view"
    android:layout_width="110dp"
    android:layout_height="wrap_content"
    android:text="food"
    android:layout_weight="1" />

    <TextView
        android:id="@+id/view1"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:text="1" 
        android:layout_weight="1"/>

     <TextView
         android:id="@+id/view2"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:text="20" 
        android:layout_weight="1"/>

    </TableRow>
    </TableLayout>

<Button
    android:id="@+id/bdelete"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Clear Log"
    android:layout_gravity="center"
    android:layout_marginTop="30dp" />

Java class of View Database page:

    public class FruitLog extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fruitlog);

            TextView tv = (TextView) findViewById(R.id.view);
            TextView tv1 = (TextView) findViewById(R.id.view1);
            TextView tv2 = (TextView) findViewById(R.id.view2);

            FruitDB info = new FruitDB(this);
            info.open();
            String data = info.getName();
            String data1 = info.getNum();
            String data2 = info.getCal();
            info.close();

            tv.setText(data);
            tv1.setText(data1);
            tv2.setText(data2);

            Button save = (Button) findViewById(R.id.bdelete);
            save.setTextColor(Color.BLUE);
            save.setOnClickListener(new View.OnClickListener(){

                public void onClick(View v) {
                    // TODO Auto-generated method stub
                    FruitDB info = new FruitDB(FruitLog.this);
                    info.open();
                    info.deleteAll();
                    info.close();
                }

            });

}

I have edited the code, now I can delete all the data in my page, but the issue is that, I have to navigate back and enter this FruitLog page to see the changes (all rows deleted).
I want to see a immediate result when the user click ‘Clear Log’ Button without navigating back and front.

Answer 1

This method in your db class:

public boolean deleteAll() {        
    // Returns true if number of deleted rows is larger than 0;
    return mDb.delete(DATABASE_TABLE, null, 1) > 0;
}

In the onClickListener:

 public void onClick(View v) {
     FruitDB db = new FruitDB(YourClass.this);
     db.open();
         db.deleteAll();
     db.close();
 }