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
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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
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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
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<?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服务器之家。
原文链接：https://blog.csdn.net/weixin_45076969/article/details/104909293
