SQLite数据库作业

安卓作业：

a)将学生信息存入数据库

b)显示所有学生信息列表

c)删除数据库表中的一条信息

 1.xml界面

   主界面

<?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:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="cn.edu.niit.sqlite.MainActivity">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="35sp"
        android:id="@+id/w"/>
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <Button
            android:textSize="20sp"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:onClick="onClick"
            android:layout_height="wrap_content"
            android:text="增加一条新记录呀"
        android:id="@+id/add"/>
        <Button
            android:textSize="20sp"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:onClick="onClick"
            android:layout_height="wrap_content"
            android:text="删除第一条记录呀"
            android:id="@+id/delete"/>
    </LinearLayout>

    <ListView
        android:layout_width="match_parent"
        android:id="@+id/t"
        android:layout_height="wrap_content">
    </ListView>
</LinearLayout>

2.创建数据库

public class MyDBHelper extends SQLiteOpenHelper {
    private static final String name = "count";
    private static final int version = 1;
    private String sql = "create table person(_id int autoincrement primary key ," +
            "name varchar(30) not null)";

    public MyDBHelper(Context context) {
        super(context, name, null, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("drop table if exists person");
        onCreate(db);
    }
3.执行删除与添加语句

public class MyDBHelper extends SQLiteOpenHelper {
    private static final String name = "count";
    private static final int version = 1;
    private String sql = "create table person(_id int autoincrement primary key ," +
            "name varchar(30) not null)";

    public MyDBHelper(Context context) {
        super(context, name, null, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("drop table if exists person");
        onCreate(db);
    }
}
4.增加Adapter方法

private void addAdp() {
    if(c!=null){
        dao = new PersonDAO(this);
        c = dao.selectAll();
        adp = new MyCursorAdpter(this,c,0);
        lv.setAdapter(adp);
    }
}
5.java代码的实现

public class MainActivity extends AppCompatActivity {
    private EditText et_name;
    private ListView data;
    private Adapter adapter;
    private StudentDAO studentDAO;
    private Cursor cursor;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        et_name = (EditText)findViewById(R.id.et_name);

        data = (ListView)findViewById(R.id.data);
        //查询数据并进行显示
        studentDAO = new StudentDAO(this);
        cursor = studentDAO.selectAll();
        if(cursor!=null){
            Adapter = new Adapter(MainActivity.this,cursor);
            data.setAdapter(adapter);
        }


    }

    public void onClick(View view) {
        switch(view.getId()){
            case R.id.add:
                //add数据
                String name = et_input.getText().toString();
                personDAO.insert(name);
                cursor = personDAO.selectAll();
                if(cursor!=null){
                    adapter = new Adapter(this,cursor);
                    data.setAdapter(adapter);
                }
                break;
            case R.id.delete:
                //delete数据
                if(cursor!=null){
                    if(cursor.moveToFirst()){
                        studentDAO.delete(cursor.getString(cursor.getColumnIndex("_id")));
                        cursor = studentDAO.selectAll();
                    }
                }
                adapter = new Adapter(this,cursor);
                data.setAdapter(adapter);
                break;
        }