android第十周（增删改查）

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout
    android:padding="16dp"
    android:orientation="vertical"
    android:background="@drawable/j"
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <LinearLayout
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:layout_marginTop="130dp">
        <TextView
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:textSize="18sp"
            android:text="姓 名 ："/>
        <EditText
            android:layout_height="wrap_content"
            android:layout_width="match_parent"
            android:textSize="16sp"
            android:hint="请输入姓名"
            android:id="@+id/et_name"/>
    </LinearLayout>
    -<LinearLayout
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:layout_marginBottom="10dp">
    <TextView
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:textSize="18sp"
        android:text="年 龄："/>
    <EditText
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:textSize="16sp"
        android:hint="输入年龄"
        android:id="@+id/et_age"/>
</LinearLayout>
    -<LinearLayout
    android:layout_height="wrap_content"
    android:layout_width="match_parent">
    <Button
        android:background="#B9B9FF"
        android:layout_height="wrap_content"
        android:layout_width="0dp"
        android:textSize="18sp"
        android:text="添加"
        android:id="@+id/btn_add"
        android:onClick="add"
        android:layout_weight="1"
        android:layout_marginRight="2dp"/>
    <Button
        android:background="#DCB5FF"
        android:layout_height="wrap_content"
        android:layout_width="0dp"
        android:textSize="18sp"
        android:text="查询"
        android:id="@+id/btn_query"
        android:onClick="search"
        android:layout_weight="1"
        android:layout_marginRight="2dp"/>
    <Button
        android:background="#E6CAFF"
        android:layout_height="wrap_content"
        android:layout_width="0dp"
        android:textSize="18sp"
        android:text="修改"
        android:id="@+id/btn_update"
        android:onClick="update"
        android:layout_weight="1"
        android:layout_marginRight="2dp"/>
    <Button
        android:background="#ACD6FF"
        android:layout_height="wrap_content"
        android:layout_width="0dp"
        android:textSize="18sp"
        android:text="删除"
        android:id="@+id/btn_delete"
        android:onClick="delete"
        android:layout_weight="1"/>
</LinearLayout>
    -<ScrollView
    android:layout_height="wrap_content"
    android:layout_width="match_parent">
    <TextView
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:layout_marginTop="25dp"
        android:textSize="20sp"
        android:id="@+id/tv_show"/>
</ScrollView>
</LinearLayout>

package com.example.shopping;

import android.os.Bundle;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
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);
    }
    public void add(View v) {
        sqlqq helper = new sqlqq(this);
        SQLiteDatabase db = helper.getWritableDatabase();
        String name = ((EditText) findViewById(R.id.et_name)).getText()
                .toString();
        int age = Integer.parseInt(((EditText) findViewById(R.id.et_age))
                .getText().toString());
        db.execSQL("insert into stuinfo (name,age) values(?,?)", new Object[] {
                name, age });
        Toast.makeText(this, "ok", 0).show();
    }
    public void delete(View view) {
        sqlqq helper = new sqlqq(this);
        SQLiteDatabase db = helper.getWritableDatabase();
        db.execSQL("delete from stuinfo where _id=?", new Object[] { 2 });
        Toast.makeText(this, "删除成功", 0).show();
    }
    public void update(View view) {
        sqlqq helper = new sqlqq(this);
        SQLiteDatabase db = helper.getWritableDatabase();
        db.execSQL("update stuinfo set name=? where _id=?", new Object[] {
                "micky", 3 });
        Toast.makeText(this, "修改成功", 0).show();
    }

    public void search(View view) {
        sqlqq helper = new sqlqq(this);
        SQLiteDatabase db = helper.getWritableDatabase();
        String s = "";
        Cursor cursor = db.rawQuery("select * from stuinfo", null);
        if (cursor.getCount() != 0) {

            while (cursor.moveToNext()) {
                s += cursor.getInt(0) + "   " + cursor.getString(1) + "   "
                        + cursor.getInt(2) + "\n";
            }
        }
        ((TextView) (findViewById(R.id.tv_show))).setText(s);
    }
}


package com.example.shopping;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class sqlqq {
    public sqlqq(Context context) {
        super(context, "stu.db", null, 1);
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table stuinfo(_id integer primary key autoincrement,name varchar(20),age integer)");
    }
    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
    }

    public SQLiteDatabase getWritableDatabase() {
    }
}