Android Studio实现简单的通讯录

package com.example.test;
 
import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.text.method.ScrollingMovementMethod;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
 
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
    MyHelper myHelper;
    private TextView tvShow;
    private Button btnAdd;
    private Button btnQuery;
    private Button btnUpdate;
 
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myHelper = new MyHelper(this);
        init();
    }
    private void init(){
        tvShow = (TextView)findViewById(R.id.tv_show);
        btnAdd = (Button)findViewById(R.id.btn_add);
        btnQuery = (Button)findViewById(R.id.btn_query);
        btnUpdate = (Button)findViewById(R.id.btn_update);
        btnAdd.setOnClickListener(this);   //Button控件设置监听
        btnQuery.setOnClickListener(this);
        btnUpdate.setOnClickListener(this);
        findViewById(R.id.traceroute_rootview).setOnClickListener(this);
        tvShow.setMovementMethod(ScrollingMovementMethod.getInstance()); //设置文本滚动
    }
    public void onClick(View v){
        SQLiteDatabase db;
        switch (v.getId()){
            case R.id.traceroute_rootview:
                InputMethodManager imm=(InputMethodManager)
                        getSystemService(Context.INPUT_METHOD_SERVICE);
                imm.hideSoftInputFromWindow(v.getWindowToken(),0);
                break;
            case R.id.btn_add:  //添加联系人
                Intent intent=new Intent(MainActivity.this,nextActivity.class);
                startActivity(intent);
                break;
            case R.id.btn_query: //查询联系人
                db = myHelper.getReadableDatabase();
                Cursor cursor = db.rawQuery("select name,phone from person",null);
                if (cursor.getCount() == 0){
                    tvShow.setText("");
                    Toast.makeText(this,"当前无联系人",Toast.LENGTH_SHORT).show();
                }else {
                    cursor.moveToFirst();
                    tvShow.setText("Name："   cursor.getString(0)   " ; Tel："   cursor.getString(1));
                    while (cursor.moveToNext()){
                        tvShow.append("\n"   "Name："   cursor.getString(0)   " ; Tel："   cursor.getString(1));
                    }
                }
                cursor.close();
                db.close();
                break;
            case R.id.btn_update: //修改联系人
                Intent intent1=new Intent(MainActivity.this,xiugaiActivity.class);
                startActivity(intent1);
                break;
        }
    }
}

package com.example.test;
 
import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.database.sqlite.SQLiteDatabase;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
 
public class nextActivity extends AppCompatActivity implements View.OnClickListener {
    MyHelper myHelper;
    private EditText etName;
    private EditText etPhone;
    private Button btnAdd;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.next);
        myHelper = new MyHelper(this);
        init();
    }
    private void init(){
        etName = (EditText)findViewById(R.id.et_name);
        etPhone = (EditText)findViewById(R.id.et_phone);
        btnAdd = (Button)findViewById(R.id.btn_add);
        btnAdd.setOnClickListener(this);   //Button控件设置监听
        findViewById(R.id.traceroute_rootview).setOnClickListener(this);
    }
    public void onClick(View v){
        String name;
        String phone;
        SQLiteDatabase db;
        switch (v.getId()) {
            case R.id.traceroute_rootview:
                InputMethodManager imm = (InputMethodManager)
                        getSystemService(Context.INPUT_METHOD_SERVICE);
                imm.hideSoftInputFromWindow(v.getWindowToken(), 0);
                break;
            case R.id.btn_add:  //添加联系人
                name = etName.getText().toString().trim();
                phone = etPhone.getText().toString().trim();
                db = myHelper.getWritableDatabase();
                if (name.equals("") || phone.equals("")) { //联系人信息不能为空
                    Toast.makeText(this, "联系人信息添加失败", Toast.LENGTH_SHORT).show();
                } else {
                    db.execSQL("insert into person (name,phone) values(?,?)", new Object[]{name, phone});
                    Toast.makeText(this, "联系人信息添加成功", Toast.LENGTH_SHORT).show();
                }
                db.close();
                Intent intent=new Intent(nextActivity.this,MainActivity.class);
                startActivity(intent);
                break;
        }
    }
}

package com.example.test;
 
import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.os.Bundle;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.text.method.ScrollingMovementMethod;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class xiugaiActivity extends AppCompatActivity implements View.OnClickListener{
    MyHelper myHelper;
    private EditText etName;
    private EditText etPhone;
    private TextView tvShow;
    private Button btnQuery;
    private Button btnUpdate;
    private Button btnDelete;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.xiugai);
        myHelper = new MyHelper(this);
        init();
    }
    private void init(){
        etName = (EditText)findViewById(R.id.et_name);
        etPhone = (EditText)findViewById(R.id.et_phone);
        tvShow = (TextView)findViewById(R.id.tv_show);
        btnQuery = (Button)findViewById(R.id.btn_query);
        btnUpdate = (Button)findViewById(R.id.btn_update);
        btnDelete = (Button)findViewById(R.id.btn_delete);
        btnQuery.setOnClickListener(this);
        btnUpdate.setOnClickListener(this);
        btnDelete.setOnClickListener(this);
        findViewById(R.id.traceroute_rootview).setOnClickListener(this);
        tvShow.setMovementMethod(ScrollingMovementMethod.getInstance()); //设置文本滚动
    }
    public void onClick(View v){
        String name;
        String phone;
        SQLiteDatabase db;
        switch (v.getId()){
            case R.id.traceroute_rootview:
                InputMethodManager imm=(InputMethodManager)
                        getSystemService(Context.INPUT_METHOD_SERVICE);
                imm.hideSoftInputFromWindow(v.getWindowToken(),0);
                break;
            case R.id.btn_query: //查询联系人
                db = myHelper.getReadableDatabase();
                Cursor cursor = db.rawQuery("select name,phone from person",null);
                if (cursor.getCount() == 0){
                    tvShow.setText("");
                    Toast.makeText(this,"当前无联系人",Toast.LENGTH_SHORT).show();
                }else {
                    cursor.moveToFirst();
                    tvShow.setText("Name："   cursor.getString(0)   " ; Tel："   cursor.getString(1));
                    while (cursor.moveToNext()){
                        tvShow.append("\n"   "Name："   cursor.getString(0)   " ; Tel："   cursor.getString(1));
                    }
                }
                cursor.close();
                db.close();
                break;
            case R.id.btn_update: //修改联系人
                db = myHelper.getWritableDatabase();
                name = etName.getText().toString().trim();
                phone = etPhone.getText().toString().trim();
                if (name.equals("") || phone.equals("")){ //联系人信息不能为空
                    Toast.makeText(this,"不存在该联系人",Toast.LENGTH_SHORT).show();
                }
                else {
                    db.execSQL("update person set name=?,phone=? where name=?", new Object[]{name, phone, name});
                    Toast.makeText(this,"联系人信息修改成功",Toast.LENGTH_SHORT).show();
                }
                db.close();
                break;
            case R.id.btn_delete: //删除联系人
                db = myHelper.getWritableDatabase();
                name = etName.getText().toString().trim();
                phone = etPhone.getText().toString().trim();
                if (name.equals("") || phone.equals("")){ //联系人信息不能为空
                    Toast.makeText(this,"不存在该联系人",Toast.LENGTH_SHORT).show();
                }
                else {
                    db.execSQL("delete from person where name=? and phone=?", new Object[]{name, phone});
                    Toast.makeText(this,"联系人信息删除成功",Toast.LENGTH_SHORT).show();
                }
                db.close();
                break;
        }
    }
}

package com.example.test;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class MyHelper extends SQLiteOpenHelper{
    public MyHelper(Context context){
        super(context, "alan.db", null ,2);
    }
    @Override
 
    public void onCreate(SQLiteDatabase db){
        db.execSQL("create table person(id integer primary key autoincrement,name varchar(20),phone varchar(20) unique)");
    }
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
 
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@ id/traceroute_rootview"
    android:background="@color/white"
    android:clickable="true"
    android:gravity="center_horizontal"
    tools:context=".MainActivity">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="通 讯 录"
            android:textSize="30dp"
            android:textStyle="italic"
            android:gravity="center"
            android:textColor="@color/black">
        </TextView>
        <Button
            android:id="@ id/btn_add"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@drawable/shape"
            android:text=" 添加联系人"
            android:textSize="16dp"
            android:textColor="#c2c8ec"
            android:textStyle="bold"/>
        <Button
            android:id="@ id/btn_query"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@drawable/shape"
            android:text="查看联系人"
            android:textSize="16dp"
            android:textColor="#c2c8ec"
            android:textStyle="bold"/>
        <Button
            android:id="@ id/btn_update"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@drawable/shape"
            android:text=" 修改联系人"
            android:textSize="16dp"
            android:textColor="#c2c8ec"
            android:textStyle="bold"/>
    <TextView
        android:id="@ id/tv_show"
        android:layout_width="match_parent"
        android:layout_height="180dp"
        android:scrollbars="vertical"
        android:layout_below="@ id/lineFour"
        android:layout_marginTop="20dp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="18dp"
        android:textColor="#c2c8ec"
        android:textSize="24dp"/>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@ id/traceroute_rootview"
    android:background="@color/white"
    android:clickable="true"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    tools:context=".nextActivity">
    <LinearLayout
        android:id="@ id/lineTwo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@ id/lineOne"
        android:layout_marginTop="20dp"
        android:layout_marginLeft="18dp"
        android:layout_marginRight="18dp">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="姓 名 : "
            android:textSize="18dp"
            android:textStyle="bold"/>
        <EditText
            android:id="@ id/et_name"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="请输入姓名"
            android:textSize="16dp"
            android:maxLines="1"
            android:singleLine="true"
            android:maxLength="14"/>
    </LinearLayout>
    <LinearLayout
        android:id="@ id/lineTree"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@ id/lineTwo"
        android:layout_marginTop="10dp"
        android:layout_marginLeft="18dp"
        android:layout_marginRight="18dp">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="电 话 : "
        android:textSize="18dp"
        android:textStyle="bold"/>
    <EditText
        android:id="@ id/et_phone"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入手机号码"
        android:textSize="16dp"
        android:maxLines="1"
        android:singleLine="true"
        android:maxLength="11"/>
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@ id/lineFour"
        android:layout_below="@ id/lineTree"
        android:layout_marginTop="30dp"
        android:layout_marginLeft="18dp"
        android:layout_marginRight="18dp"
        android:orientation="horizontal">
    <Button
        android:id="@ id/btn_add"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/shape"
        android:layout_weight="1"
        android:text=" 确 定 "
        android:textSize="16dp"
        android:textColor="#c2c8ec"
        android:textStyle="bold"/>
    </LinearLayout>
</RelativeLayout>
xiugai.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@ id/traceroute_rootview"
    android:background="@color/white"
    android:clickable="true"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    tools:context=".xiugaiActivity">
    <LinearLayout
        android:id="@ id/lineTwo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@ id/lineOne"
        android:layout_marginTop="20dp"
        android:layout_marginLeft="18dp"
        android:layout_marginRight="18dp">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="姓 名 : "
            android:textSize="18dp"
            android:textStyle="bold"/>
        <EditText
            android:id="@ id/et_name"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="  请输入姓名"
            android:textSize="16dp"
            android:maxLines="1"
            android:singleLine="true"
            android:maxLength="14"/>
    </LinearLayout>
    <LinearLayout
        android:id="@ id/lineTree"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@ id/lineTwo"
        android:layout_marginTop="10dp"
        android:layout_marginLeft="18dp"
        android:layout_marginRight="18dp">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="电 话 : "
            android:textSize="18dp"
            android:textStyle="bold"/>
        <EditText
            android:id="@ id/et_phone"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="  请输入手机号码"
            android:textSize="16dp"
            android:maxLines="1"
            android:singleLine="true"
            android:maxLength="11"/>
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@ id/lineFour"
        android:layout_below="@ id/lineTree"
        android:layout_marginTop="30dp"
        android:layout_marginLeft="18dp"
        android:layout_marginRight="18dp"
        android:orientation="horizontal">
        <Button
            android:id="@ id/btn_query"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/shape"
            android:layout_weight="1"
            android:layout_marginLeft="4dp"
            android:text="查看联系人"
            android:textSize="16dp"
            android:textColor="#c2c8ec"
            android:textStyle="bold"/>
        <Button
            android:id="@ id/btn_update"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/shape"
            android:layout_weight="1"
            android:layout_marginLeft="4dp"
            android:text=" 修 改 "
            android:textSize="16dp"
            android:textColor="#c2c8ec"
            android:textStyle="bold"/>
        <Button
            android:id="@ id/btn_delete"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/shape"
            android:layout_weight="1"
            android:layout_marginLeft="4dp"
            android:text=" 删 除 "
            android:textSize="16dp"
            android:textColor="#c2c8ec"
            android:textStyle="bold"/>
    </LinearLayout>
    <TextView
        android:id="@ id/tv_show"
        android:layout_width="match_parent"
        android:layout_height="180dp"
        android:scrollbars="vertical"
        android:layout_below="@ id/lineFour"
        android:layout_marginTop="20dp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="18dp"
        android:textColor="#c2c8ec"
        android:textSize="24dp"/>
</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.test">
 
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Test">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
 
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".nextActivity"></activity>
        <activity android:name=".xiugaiActivity"></activity>
    </application>
 
</manifest>