<?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:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" android:background="@drawable/bg" android:padding="16dp" android:orientation="vertical"> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="130dp" android:orientation="horizontal" > <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="姓 名：" android:textSize="18sp" /> <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="16sp" /> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="15dp" > <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="电 话：" android:textSize="18sp" /> <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="16sp" /> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="15dp" > <Button android:id="@+id/btn_add" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginRight="2dp" android:layout_weight="1" android:background="#E6CAFF" android:text="添加" android:textSize="18sp"/> <Button android:id="@+id/btn_query" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginRight="2dp" android:layout_weight="1" android:background="#E6CAFF" android:text="查询" android:textSize="18sp"/> <Button android:id="@+id/btn_update" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginRight="2dp" android:layout_weight="1" android:background="#E6CAFF" android:text="修改" android:textSize="18sp"/> <Button android:id="@+id/btn_delete" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginRight="2dp" android:layout_weight="1" android:background="#E6CAFF" android:text="删除" android:textSize="18sp"/> </LinearLayout> <TextView android:id="@+id/tv_show" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="25dp" android:textSize="20sp" /></LinearLayout>
package com.example.myapplication;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;import androidx.appcompat.app.AppCompatActivity;public class MainActivity extends AppCompatActivity implements View.OnClickListener { MyHelper myHelper; private EditText mEtName; private EditText mEtPhone; private TextView mTvShow; private Button mBtnAdd; private Button mBtnQuery; private Button mBtnUpdate; private Button mBtnDelete; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); myHelper=new MyHelper(this); init(); } private void init(){ mEtName=(EditText)findViewById(R.id.et_name); mEtPhone=(EditText)findViewById(R.id.et_phone); mTvShow=(TextView)findViewById(R.id.tv_show); mBtnAdd=(Button)findViewById(R.id.btn_add); mBtnQuery=(Button)findViewById(R.id.btn_query); mBtnUpdate=(Button)findViewById(R.id.btn_update); mBtnDelete=(Button)findViewById(R.id.btn_delete); mBtnAdd.setOnClickListener(this); mBtnQuery.setOnClickListener(this); mBtnUpdate.setOnClickListener(this); mBtnDelete.setOnClickListener(this); } public void onClick(View view){ String name,phone; SQLiteDatabase db; ContentValues values; switch (view.getId()){ case R.id.btn_add: name=mEtName.getText().toString(); phone=mEtPhone.getText().toString(); db=myHelper.getWritableDatabase(); values=new ContentValues(); values.put("name",name); values.put("phone",phone); db.insert("information",null,values); Toast.makeText(this,"信息已添加",Toast.LENGTH_LONG).show(); db.close(); break; case R.id.btn_query: db=myHelper.getReadableDatabase(); Cursor cursor=db.query("information",null,null,null,null,null,null); if (cursor.getCount()==0){ mTvShow.setText(""); Toast.makeText(this,"没有数据",Toast.LENGTH_LONG).show(); }else { cursor.moveToFirst(); mTvShow.setText("Name:"+cursor.getString(1)+"Tel:"+cursor.getString(2)); } while (cursor.moveToNext()){ mTvShow.append("\n"+"Name:"+cursor.getString(1)+"Tel:"+cursor.getString(2)); } cursor.close(); db.close(); break; case R.id.btn_update: db=myHelper.getWritableDatabase(); values=new ContentValues(); values.put("phone",phone=mEtPhone.getText().toString()); db.update("information",values,"name=?",new String[]{mEtName.getText().toString()}); Toast.makeText(this,"信息已修改",Toast.LENGTH_LONG).show(); db.close(); break; case R.id.btn_delete: db=myHelper.getWritableDatabase(); db.delete("information","name=?",new String[]{mEtName.getText().toString()}); Toast.makeText(this,"信息已删除",Toast.LENGTH_LONG).show(); mTvShow.setText(""); db.close(); break; } } class MyHelper extends SQLiteOpenHelper{ public MyHelper(Context context){ super(context,"itcast.db",null,1); } public void onCreate(SQLiteDatabase db){ db.execSQL("CREATE TABLE information(_id INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR(20),phone VARCHAR(20))"); } public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion){ } }}
