Android实现通讯录功能

本文实例为大家分享了Android 通讯录案例，供大家参考，具体内容如下

实战演练——通讯录

1、功能描述：通过SQLite实现数据库的增删改查

2、技术要点：SQLite的基本操作

3、实现步骤：

① 创建一个类继承SQLiteOpenHelper
② 重写父类构造方法、onCreate()、onUpgrade()
③ 增删改查

4、效果图

5、案例代码

MyHelper.java

package com.example.sqlite;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import androidx.annotation.Nullable;

public class MyHelper extends SQLiteOpenHelper {
  public MyHelper(@Nullable Context context) {
    super(context, \"test.db\", null, 1);
  }

  //当数据库第一次创建的时候执行
  @Override
  public void onCreate(SQLiteDatabase db) {
    db.execSQL(\"CREATE TABLE information(_id INTEGER PRIMARY KEY AUTOINCREMENT ,name VARCHAR(20),phone VARCHAR(20))\");
  }

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
  }
}

MainActivity.java

package com.example.sqlite;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
  private TextView name;
  private TextView phone;
  private Button btnAdd;
  private Button btnDel;
  private Button btnUqd;
  private Button btnSel;
  private String uPhone;
  private String uName;
  private MyHelper myHelper;
  private SQLiteDatabase db;
  private TextView show;
  private ContentValues contentValues;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    myHelper = new MyHelper(this);
    init();
  }

  private void init() {
    show = findViewById(R.id.show);
    name = findViewById(R.id.name);
    phone = findViewById(R.id.phone);
    btnAdd = findViewById(R.id.insert);
    btnDel = findViewById(R.id.delete);
    btnUqd = findViewById(R.id.update);
    btnSel = findViewById(R.id.select);
    btnAdd.setOnClickListener(this);
    btnDel.setOnClickListener(this);
    btnUqd.setOnClickListener(this);
    btnSel.setOnClickListener(this);
  }

  @Override
  public void onClick(View v) {
    switch (v.getId()) {
      case R.id.select:
        db = myHelper.getReadableDatabase();
        Cursor cursor = db.query(\"information\", null, null, null, null, null, null);
        if (cursor.getCount() == 0) {
          Toast.makeText(this, \"没有数据\", Toast.LENGTH_LONG).show();
        } else {
          cursor.moveToFirst();
          show.setText(\"Name:\" + cursor.getString(1) + \"Tel:\" + cursor.getString(2));
        }
        while (cursor.moveToNext()) {
          show.append(\"\\n\" + \"Name\" + cursor.getString(1) + \"Tel\" + cursor.getString(2));
        }
        cursor.close();
        db.close();
        break;
      case R.id.insert:
        uName = name.getText().toString();
        uPhone = phone.getText().toString();
        db = myHelper.getReadableDatabase();
        contentValues = new ContentValues();
        contentValues.put(\"name\", uName);
        contentValues.put(\"phone\", uPhone);
        db.insert(\"information\", null, contentValues);
        db.close();
        break;
      case R.id.update:
        db = myHelper.getReadableDatabase();
        contentValues = new ContentValues();
        contentValues.put(\"phone\", uPhone = phone.getText().toString());
        db.update(\"information\", contentValues, \"name=?\", new String[]{name.getText().toString()});
        db.close();
        break;
      case R.id.delete:
        db = myHelper.getReadableDatabase();
        db.delete(\"information\", null, null);
        Toast.makeText(this, \"信息已经删除\", Toast.LENGTH_LONG).show();
        show.setText(\"\");
        db.close();
        break;
    }
  }
}

activity_main.xml

<?xml version=\"1.0\" encoding=\"utf-8\"?>
<RelativeLayout xmlns:android=\"http://schemas.android.com/apk/res/android\"
  xmlns:app=\"http://schemas.android.com/apk/res-auto\"
  xmlns:tools=\"http://schemas.android.com/tools\"
  android:layout_width=\"match_parent\"
  android:layout_height=\"match_parent\"
  tools:context=\".MainActivity\"
  android:background=\"@drawable/background\">
  <LinearLayout
    android:layout_width=\"match_parent\"
    android:layout_height=\"match_parent\"
    android:orientation=\"vertical\"
    >
    <LinearLayout
      android:layout_width=\"match_parent\"
      android:layout_height=\"wrap_content\"
      android:orientation=\"horizontal\"
      >

      <ImageView
        android:layout_width=\"160dp\"
        android:layout_height=\"120dp\"
        android:layout_marginTop=\"50dp\"
        android:layout_marginLeft=\"20dp\"
        android:src=\"@drawable/expression\"></ImageView>
      <ImageView
        android:layout_width=\"160dp\"
        android:layout_height=\"120dp\"
        android:layout_marginTop=\"50dp\"
        android:layout_marginLeft=\"20dp\"
        android:src=\"@drawable/text\"></ImageView>
    </LinearLayout>
    <LinearLayout
      android:layout_width=\"match_parent\"
      android:layout_height=\"wrap_content\"
      android:orientation=\"horizontal\"
      android:layout_marginTop=\"20dp\"
      android:paddingHorizontal=\"20dp\"
      >
      <TextView

        android:layout_width=\"0dp\"
        android:layout_height=\"wrap_content\"
        android:layout_weight=\"1\"
        android:text=\"姓 名 :\"
        android:textSize=\"26sp\"
        app:layout_constraintBottom_toBottomOf=\"parent\"
        app:layout_constraintLeft_toLeftOf=\"parent\"
        app:layout_constraintRight_toRightOf=\"parent\"
        app:layout_constraintTop_toTopOf=\"parent\" />
      <EditText
        android:id=\"@+id/name\"
        android:layout_width=\"0dp\"
        android:layout_weight=\"3\"
        android:layout_height=\"wrap_content\"
        android:hint=\"请输入姓名\"
        android:textSize=\"22sp\"
        ></EditText>

    </LinearLayout>
    <LinearLayout
      android:layout_width=\"match_parent\"
      android:layout_height=\"wrap_content\"
      android:orientation=\"horizontal\"
      android:layout_marginTop=\"20dp\"
      android:paddingHorizontal=\"20dp\"
      >
      <TextView
        android:layout_width=\"0dp\"
        android:layout_height=\"wrap_content\"
        android:layout_weight=\"1\"
        android:text=\"电 话 :\"
        android:textSize=\"26sp\"
        app:layout_constraintBottom_toBottomOf=\"parent\"
        app:layout_constraintLeft_toLeftOf=\"parent\"
        app:layout_constraintRight_toRightOf=\"parent\"
        app:layout_constraintTop_toTopOf=\"parent\" />
      <EditText
        android:id=\"@+id/phone\"
        android:layout_width=\"0dp\"
        android:layout_weight=\"3\"
        android:layout_height=\"wrap_content\"
        android:hint=\"请输入手机号码\"
        android:textSize=\"22sp\"
        ></EditText>

    </LinearLayout>
    <LinearLayout
      android:layout_width=\"match_parent\"
      android:layout_height=\"wrap_content\"
      android:orientation=\"horizontal\"
      android:layout_marginTop=\"20dp\"
      android:paddingHorizontal=\"20dp\"
      >
      <Button
        android:id=\"@+id/insert\"
        android:layout_width=\"0dp\"
        android:layout_weight=\"1\"
        android:layout_height=\"wrap_content\"
        android:text=\"增加\"
        android:textSize=\"26sp\"
        ></Button>
      <Button
        android:id=\"@+id/select\"
        android:layout_width=\"0dp\"
        android:layout_weight=\"1\"
        android:layout_height=\"wrap_content\"
        android:text=\"查询\"
        android:textSize=\"26sp\"
        ></Button>
      <Button
        android:id=\"@+id/update\"
        android:layout_width=\"0dp\"
        android:layout_weight=\"1\"
        android:layout_height=\"wrap_content\"
        android:text=\"修改\"
        android:textSize=\"26sp\"
        ></Button>
      <Button
        android:id=\"@+id/delete\"
        android:layout_width=\"0dp\"
        android:layout_weight=\"1\"
        android:layout_height=\"wrap_content\"
        android:text=\"删除\"
        android:textSize=\"26sp\"
        ></Button>
    </LinearLayout>
    <TextView
      android:id=\"@+id/show\"
      android:layout_width=\"match_parent\"
      android:layout_height=\"wrap_content\"
      android:gravity=\"center\"
      android:textSize=\"18sp\"
      android:background=\"#80ffffff\"
      android:layout_marginHorizontal=\"20dp\"

      ></TextView>
  </LinearLayout>
</RelativeLayout>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持自学编程网。