5。建库，表，增删改查
import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper; import androidx.annotation.Nullable; public class StuOpenHelper extends SQLiteOpenHelper { public StuOpenHelper(@Nullable Context context) { super(context, "stu.db", null, 1); } @Override public void onCreate(SQLiteDatabase sqLiteDatabase) { sqLiteDatabase.execSQL("create table student (id integer primary key autoincrement ,name varchar(20),price integer)"); } @Override public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) { }} |
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import androidx.appcompat.app.AppCompatActivity; import android.annotation.SuppressLint;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.View;import android.widget.TextView;import android.widget.Toast; public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } @SuppressLint("WrongConstant") public void add(View view){ String name = ((TextView)findViewById(R.id.et_name)).getText().toString(); int age = Integer.parseInt(((TextView)findViewById(R.id.et_age)).getText().toString()); StuOpenHelper stuOpenHelper=new StuOpenHelper(this); SQLiteDatabase db = stuOpenHelper.getReadableDatabase(); db.execSQL("insert into student (name,price) values(?,?)",new Object[]{name,age}); Toast.makeText(this,"ok",0).show(); } public void serch(View view){ StuOpenHelper stuOpenHelper=new StuOpenHelper(this); SQLiteDatabase db = stuOpenHelper.getReadableDatabase(); String s=""; Cursor cursor = db.rawQuery("SELECT * from student", null); while (cursor.getCount()!=0){ while (cursor.moveToNext()){ s+=cursor.getInt(0)+" "+cursor.getInt(1)+" "+cursor.getInt(2)+"\n"; } } ((TextView)(findViewById(R.id.tv_show))).setText(s); }} |
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<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@drawable/bg" android:padding="16dp" android:orientation="vertical"> <LinearLayout android:layout_marginTop="130dp" android:layout_width="match_parent" android:layout_height="wrap_content"> <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:layout_marginBottom="10dp"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="年 龄：" android:textSize="18sp" /> <EditText android:id="@+id/et_age" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="输入年龄" android:textSize="16sp" /> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content"> <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="#B9B9FF" android:text="添加" android:textSize="18sp" android:onClick="add" /> <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="#DCB5FF" android:text="查询" android:textSize="18sp" android:onClick="serch"/> <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" android:onClick="update"/> <Button android:id="@+id/btn_delete" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:background="#ACD6FF" android:text="删除" android:textSize="18sp" android:onClick="delete" /> </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> |
