Android Studio中实现通讯录代码

以下是一个简单的示例，演示如何在Android Studio中实现通讯录代码。该示例使用SQLite数据库来存储联系人信息。

1. 创建一个新的Android Studio项目，包含一个Activity和一个布局文件。

2. 在布局文件中添加一个RecyclerView，用于显示联系人列表。

3. 创建一个数据模型类，用于表示联系人信息。例如：

public class Contact {
    private int id;
    private String name;
    private String phoneNumber;

    public Contact(int id, String name, String phoneNumber) {
        this.id = id;
        this.name = name;
        this.phoneNumber = phoneNumber;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }
}

4. 创建一个SQLite数据库帮助类，用于管理联系人信息的存储和检索。例如：

public class DatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "contacts.db";
    private static final int DATABASE_VERSION = 1;
    private static final String TABLE_NAME = "contacts";
    private static final String COLUMN_ID = "id";
    private static final String COLUMN_NAME = "name";
    private static final String COLUMN_PHONE_NUMBER = "phone_number";

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String query = "CREATE TABLE " + TABLE_NAME + " (" +
                COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                COLUMN_NAME + " TEXT, " +
                COLUMN_PHONE_NUMBER + " TEXT)";
        db.execSQL(query);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }

    public void addContact(Contact contact) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_NAME, contact.getName());
        values.put(COLUMN_PHONE_NUMBER, contact.getPhoneNumber());
        db.insert(TABLE_NAME, null, values);
        db.close();
    }

    public Contact getContact(int id) {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.query(TABLE_NAME, new String[] { COLUMN_ID, COLUMN_NAME, COLUMN_PHONE_NUMBER },
                COLUMN_ID + "=?", new String[] { String.valueOf(id) }, null, null, null, null);
        if (cursor != null)
            cursor.moveToFirst();
        Contact contact = new Contact(Integer.parseInt(cursor.getString(0)),
                cursor.getString(1), cursor.getString(2));
        cursor.close();
        db.close();
        return contact;
    }

    public List<Contact> getAllContacts() {
        List<Contact> contactList = new ArrayList<>();
        String query = "SELECT * FROM " + TABLE_NAME;
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(query, null);
        if (cursor.moveToFirst()) {
            do {
                Contact contact = new Contact(Integer.parseInt(cursor.getString(0)),
                        cursor.getString(1), cursor.getString(2));
                contactList.add(contact);
            } while (cursor.moveToNext());
        }
        cursor.close();
        db.close();
        return contactList;
    }

    public void updateContact(Contact contact) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_NAME, contact.getName());
        values.put(COLUMN_PHONE_NUMBER, contact.getPhoneNumber());
        db.update(TABLE_NAME, values, COLUMN_ID + "=?", new String[] { String.valueOf(contact.getId()) });
        db.close();
    }

    public void deleteContact(Contact contact) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete(TABLE_NAME, COLUMN_ID + "=?", new String[] { String.valueOf(contact.getId()) });
        db.close();
    }
}

5. 在Activity中初始化RecyclerView和数据库帮助类，并为其提供数据源。例如：

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private RecyclerView.Adapter adapter;
    private List<Contact> contactList = new ArrayList<>();
    private DatabaseHelper databaseHelper;

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

        recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        databaseHelper = new DatabaseHelper(this);
        contactList = databaseHelper.getAllContacts();

        adapter = new ContactAdapter(contactList);
        recyclerView.setAdapter(adapter);
    }
}

6. 创建一个RecyclerView的适配器，用于将联系人信息显示在列表中。例如：

public class ContactAdapter extends RecyclerView.Adapter<ContactAdapter.ViewHolder> {
    private List<Contact> contactList;

    public static class ViewHolder extends RecyclerView.ViewHolder {
        public TextView nameTextView;
        public TextView phoneNumberTextView;

        public ViewHolder(View view) {
            super(view);
            nameTextView = view.findViewById(R.id.name_text_view);
            phoneNumberTextView = view.findViewById(R.id.phone_number_text_view);
        }
    }

    public ContactAdapter(List<Contact> contactList) {
        this.contactList = contactList;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.contact_item, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Contact contact = contactList.get(position);
        holder.nameTextView.setText(contact.getName());
        holder.phoneNumberTextView.setText(contact.getPhoneNumber());
    }

    @Override
    public int getItemCount() {
        return contactList.size();
    }
}

7. 最后，我们可以在Activity中添加一些逻辑来处理用户添加、编辑和删除联系人的操作。例如：

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private RecyclerView.Adapter adapter;
    private List<Contact> contactList = new ArrayList<>();
    private DatabaseHelper databaseHelper;

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

        recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        databaseHelper = new DatabaseHelper(this);
        contactList = databaseHelper.getAllContacts();

        adapter = new ContactAdapter(contactList);
        recyclerView.setAdapter(adapter);

        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                showAddContactDialog();
            }
        });
    }

    private void showAddContactDialog() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Add contact");

        LayoutInflater inflater = getLayoutInflater();
        View dialogView = inflater.inflate(R.layout.dialog_add_contact, null);
        final EditText nameEditText = dialogView.findViewById(R.id.name_edit_text);
        final EditText phoneNumberEditText = dialogView.findViewById(R.id.phone_number_edit_text);
        builder.setView(dialogView);

        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                String name = nameEditText.getText().toString();
                String phoneNumber = phoneNumberEditText.getText().toString();
                Contact contact = new Contact(-1, name, phoneNumber);
                databaseHelper.addContact(contact);
                contactList.add(contact);
                adapter.notifyDataSetChanged();
            }
        });

        builder.setNegativeButton("Cancel", null);

        AlertDialog dialog = builder.create();
        dialog.show();
    }
}

这样，我们就完成了一个简单的通讯录应用程序。用户可以使用该应用程序添加、编辑和删除联系人，并在RecyclerView中查看所有联系人信息。