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Android beginner tutorial: Part 73 - Deleting contacts | App Code for Sale | Preview

Android beginner tutorial: Part 73 - Deleting contacts | Android Tutorial

How to delete contacts

Overview PAGE TOP

In this tutorial we will make it possible to delete contacts.

First of all, we'll go to onCreate() function and instead of listening to an item click event, we'll listen to item long click event. The handler is the same:

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

ListView list = (ListView)findViewById(R.id.contactList);
list.setOnItemLongClickListener(new OnItemLongClickListener() {
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
dialogEdit(position, id);
return true;
}
});

updateList();
}

We're listening to long clicks, because we need to reserve normal clicks for a more common action than editing or deleting the contacts. Later we'll make the application call the contact's number when it is clicked.

Now go to the dialogEdit() function.

We're going to add a second button (a negative one) to the Dialog and label it "Delete". When clicked, the delete() method of the ContentResolver object will be called. This part is easy and doesn't require many lines:

builder.setNegativeButton("Delete", new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {
getContentResolver().delete(CONTENT_URI, myDbHelper._ID+"="+id, null);
updateList();
}
});

Full code so far:

package com.kircode.codeforfood_test;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.DialogInterface;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.widget.SimpleCursorAdapter;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.EditText;
import android.widget.ListAdapter;
import android.widget.ListView;

public class MainActivity extends Activity{

private static final Uri CONTENT_URI = Uri.parse("content://com.kircode.codeforfood_test.mycontentprovider/contacts");
private static final int IDM_ADD = 101;

private AlertDialog addDialog;
private AlertDialog editDialog;
private View alertView;
private Cursor cursor;

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

ListView list = (ListView)findViewById(R.id.contactList);
list.setOnItemLongClickListener(new OnItemLongClickListener() {
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
dialogEdit(position, id);
return true;
}
});

updateList();
}

@Override
public boolean onCreateOptionsMenu(Menu menu){
menu.add(Menu.NONE, IDM_ADD, Menu.NONE, "Add");
return(super.onCreateOptionsMenu(menu));
}

@Override
public boolean onOptionsItemSelected(MenuItem item){
switch(item.getItemId()){
case IDM_ADD:
dialogAdd();
break;
}
return(super.onOptionsItemSelected(item));
}

public void dialogAdd(){
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);

LayoutInflater inflater = LayoutInflater.from(getApplicationContext());
alertView = inflater.inflate(R.layout.add_window, null);
builder.setView(alertView);

builder.setTitle("Add contact");

builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {
EditText t_name = (EditText)alertView.findViewById(R.id.inp_name);
EditText t_phone = (EditText)alertView.findViewById(R.id.inp_phone);
String new_name = t_name.getText().toString();
String new_phone = t_phone.getText().toString();
ContentValues values = new ContentValues();
values.put(myDbHelper.NAME, new_name);
values.put(myDbHelper.PHONE, new_phone);
getContentResolver().insert(CONTENT_URI, values);
updateList();
}
});

builder.setCancelable(true);
addDialog = builder.create();

addDialog.show();
}

public void dialogEdit(final int position, final long id){
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);

LayoutInflater inflater = LayoutInflater.from(getApplicationContext());
alertView = inflater.inflate(R.layout.add_window, null);
builder.setView(alertView);

builder.setTitle("Edit contact");

builder.setPositiveButton("Save", new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {
EditText t_name = (EditText)alertView.findViewById(R.id.inp_name);
EditText t_phone = (EditText)alertView.findViewById(R.id.inp_phone);
String new_name = t_name.getText().toString();
String new_phone = t_phone.getText().toString();
ContentValues values = new ContentValues();
values.put(myDbHelper.NAME, new_name);
values.put(myDbHelper.PHONE, new_phone);
getContentResolver().update(CONTENT_URI, values, myDbHelper._ID+"="+id, null);
updateList();
}
});

builder.setNegativeButton("Delete", new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {
getContentResolver().delete(CONTENT_URI, myDbHelper._ID+"="+id, null);
updateList();
}
});

builder.setCancelable(true);

EditText t_name = (EditText)alertView.findViewById(R.id.inp_name);
EditText t_phone = (EditText)alertView.findViewById(R.id.inp_phone);
cursor.moveToPosition(position);
t_name.setText(cursor.getString(1));
t_phone.setText(cursor.getString(2));

editDialog = builder.create();
editDialog.show();
}

public void updateList(){
String[] columns = new String[] {myDbHelper._ID, myDbHelper.NAME, myDbHelper.PHONE};
ContentResolver resolver = getContentResolver();
cursor = resolver.query(CONTENT_URI, columns, null, null, null);

final ListAdapter adapter = new SimpleCursorAdapter(this, R.layout.customrow, cursor, new String[] {myDbHelper.NAME, myDbHelper.PHONE}, new int[] {R.id.t_name, R.id.t_phone}, 0);
ListView list = (ListView)findViewById(R.id.contactList);
list.setAdapter(adapter);
}

}

Now we can edit and delete items by long-clicking the contacts in the list.

That's all for today!

Thanks for reading!

Reference PAGE TOP

http://kirill-poletaev.blogspot.it/2013/02/android-beginner-tutorial-part-73.html

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