android数据库字段类型修改 安卓数据库编辑

Step 1：效果图

Step 2目录结构：

Step 3：AndroidManifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.sqlitedemo">

    <application
        //注意此处
        android:name=".Myapp"
        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/AppTheme">
        <activity android:name=".LoginActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".MainActivity"/>
        <activity android:name=".ShowMainActivity"/>
        <activity android:name=".UpdateMainActivity"/>
        <activity android:name=".RegistActivity"/>
        <activity android:name=".SendActivity"/>
    </application>

</manifest>

Step 4：所有布局文件

<?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:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:orientation="horizontal"
        android:background="#018BD4">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="登入"
            android:textSize="20sp"
            android:gravity="center"
            android:textColor="#fff"/>

    </LinearLayout>
<EditText 
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:hint="请输入用户名"
    android:id="@+id/uesrname"
    android:layout_marginLeft="30dp"
    android:layout_marginRight="30dp"
    android:layout_marginTop="30dp"
    android:background="@drawable/input_edit"
    android:paddingLeft="10dp"/>

<EditText 
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:hint="请输入密码"
    android:id="@+id/password"
    android:layout_marginLeft="30dp"
    android:layout_marginRight="30dp"
    android:layout_marginTop="20dp"
    android:background="@drawable/input_edit"
    android:paddingLeft="10dp"/>

<Button 
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:layout_marginLeft="30dp"
    android:layout_marginRight="30dp"
    android:layout_marginTop="40dp"
    android:text="立即登入"
    android:background="@drawable/input_button"
    android:layout_gravity="center"
    android:id="@+id/loginbtn"
    android:textColor="#ffffff"/>

<Button 
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:layout_marginLeft="30dp"
    android:layout_marginRight="30dp"
    android:layout_marginTop="20dp"
    android:text="立即注册"
    android:background="@drawable/input_button"
    android:layout_gravity="center"
    android:id="@+id/regbtn"
    android:textColor="#ffffff"/>
</LinearLayout>

<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"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:orientation="horizontal"
        android:background="#018BD4">

        <TextView
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:text="新闻中心"
            android:textSize="20sp"
            android:gravity="center"
            android:paddingLeft="60dp"
            android:textColor="#fff"/>

        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:text="发布"
            android:id="@+id/sendbtn"
            android:background="#018BD4"
            android:textColor="#fff"/>

    </LinearLayout>

    <ListView
        android:divider="#666"
        android:dividerHeight="1dp"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/listview">
    </ListView>
</LinearLayout>

<?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:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="#018BD4"
        android:orientation="horizontal">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="注册"
            android:textColor="#fff"
            android:textSize="20sp" />

    </LinearLayout>

    <EditText
        android:id="@+id/reg_username"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_marginTop="50dp"
        android:background="@drawable/input_edit"
        android:hint="请输入用户名"
        android:paddingLeft="10dp" />

    <EditText
        android:id="@+id/reg_password"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_marginTop="20dp"
        android:background="@drawable/input_edit"
        android:hint="请输入密码"
        android:paddingLeft="10dp" />

    <EditText
        android:id="@+id/reg_age"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_marginTop="20dp"
        android:background="@drawable/input_edit"
        android:hint="请输入年龄"
        android:paddingLeft="10dp" />

    <EditText
        android:id="@+id/reg_sex"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_marginTop="20dp"
        android:background="@drawable/input_edit"
        android:hint="请输入性别"
        android:paddingLeft="10dp" />

    <Button
        android:id="@+id/reg_ok_btn"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_gravity="center"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_marginTop="50dp"
        android:background="@drawable/input_button"
        android:text="立即注册"
        android:textColor="#ffffff" />
</LinearLayout>

<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"
    android:orientation="vertical" >

    <TextView
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="发布新闻"
        android:gravity="center"
        android:background="#018BD4" 
        android:textColor="#fff"
        android:textSize="20sp"/>

    <EditText 
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:hint="请输入新闻标题"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_marginTop="20dp"
        android:id="@+id/edit_title"
        android:background="@null"
        android:paddingLeft="20dp"/> 

    <TextView 
        android:layout_width="match_parent"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_height="1dp"
        android:background="#018BD4"/>

     <EditText 
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:hint="请输入新闻内容"
        android:paddingLeft="20dp"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_marginTop="20dp"
        android:id="@+id/edit_content"
        android:background="@null"/>

        <TextView 
        android:layout_width="match_parent"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_height="1dp"
        android:background="#018BD4"/>

     <Button 
         android:layout_width="match_parent"
         android:layout_height="50dp"
         android:layout_marginLeft="40dp"
         android:layout_marginRight="40dp"
         android:layout_marginTop="50dp"
         android:textColor="#fff"
         android:background="@drawable/input_button"
         android:id="@+id/sendNews_btn"
         android:text="立即发布"
         />

</LinearLayout>

<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"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="#018BD4"
        android:orientation="horizontal">

        <TextView
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="新闻详情"
            android:textColor="#fff"
            android:textSize="20sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="10dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="新闻标题："
            android:textSize="20sp" />

        <TextView
            android:id="@+id/info_title"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="-"
            android:textSize="16sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="10dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="新闻内容："
            android:textSize="20sp" />

        <TextView
            android:id="@+id/info_content"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="-"
            android:textSize="16sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="10dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="新闻时间："
            android:textSize="20sp" />

        <TextView
            android:id="@+id/info_time"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="-"
            android:textSize="16sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="10dp">

        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="新闻作者："
            android:textSize="20sp" />

        <TextView
            android:id="@+id/info_author"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="-"
            android:textSize="16sp" />

    </LinearLayout>

</LinearLayout>

<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"
    android:orientation="vertical" >


    <TextView
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="修改新闻"
        android:gravity="center"
        android:background="#018BD4" 
        android:textColor="#fff"
        android:textSize="20sp"/>

    <EditText 
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:hint="请输入新闻标题"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_marginTop="20dp"
        android:id="@+id/update_title"
        android:background="@null"
        android:paddingLeft="20dp"/> 

    <TextView 
        android:layout_width="match_parent"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_height="1dp"
        android:background="#018BD4"/>

     <EditText 
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:hint="请输入新闻内容"
        android:paddingLeft="20dp"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_marginTop="20dp"
        android:id="@+id/update_content"
        android:background="@null"/>

        <TextView 
        android:layout_width="match_parent"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_height="1dp"
        android:background="#018BD4"/>

     <Button 
         android:layout_width="match_parent"
         android:layout_height="50dp"
         android:layout_marginLeft="40dp"
         android:layout_marginRight="40dp"
         android:layout_marginTop="50dp"
         android:textColor="#fff"
         android:background="@drawable/input_button"
         android:id="@+id/updateNews_btn"
         android:text="修改"
         android:gravity="center"/>

</LinearLayout>

<?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:orientation="vertical">


    <TextView
        android:id="@+id/item_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="标题"
        android:padding="10dp"
        android:textSize="25sp"
        android:textStyle="bold" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/item_username"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="用户"
            android:textSize="20sp" />


        <TextView
            android:gravity="left"
            android:paddingRight="20dp"
            android:id="@+id/item_time"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </LinearLayout>
</LinearLayout>

Step 4：所有java文件

package com.example.sqlitedemo;

import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

/**
 * 登入类
 */
public class LoginActivity extends Activity {

    private EditText username, password;
    private Button loginbtn, regbtn;

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

        username = (EditText) findViewById(R.id.uesrname);
        password = (EditText) findViewById(R.id.password);
        loginbtn = (Button) findViewById(R.id.loginbtn);
        regbtn = (Button) findViewById(R.id.regbtn);

        regbtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                //跳转至注册界面
                startActivity(new Intent(LoginActivity.this, RegistActivity.class));
            }
        });
        loginbtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                // 登入
                String un = username.getText().toString();
                String pw = password.getText().toString();
                if (TextUtils.isEmpty(un)) {
                    Toast.makeText(LoginActivity.this, "用户名不能为空", Toast.LENGTH_LONG).show();
                    return;
                } else if (TextUtils.isEmpty(pw)) {
                    Toast.makeText(LoginActivity.this, "密码不能为空", Toast.LENGTH_LONG).show();
                    return;
                } else {
                    //查询user表中是否存在该账号和密码
                    SQLiteDatabase db = Myapp.db.getReadableDatabase();
                    //查询的语句 条件是名字和密码
                    String sql = "select * from user where username= '" + un + "' and password='" + pw + "'";
                    db.rawQuery(sql, null);
                    Cursor cursor = db.rawQuery(sql, null);
                    if (cursor.getCount() > 0) {
                        Myapp.username = un;
                        Toast.makeText(LoginActivity.this, "登入成功", Toast.LENGTH_LONG).show();
                        startActivity(new Intent(LoginActivity.this, MainActivity.class));
                        finish();
                    } else {
                        Toast.makeText(LoginActivity.this, "用户名或密码错误", Toast.LENGTH_LONG).show();
                    }
                }
            }
        });
    }
}

package com.example.sqlitedemo;

import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MainActivity extends AppCompatActivity {


    private Button sendbtnButton;
    private ListView listView;
    private List<Map<String, String>> list = new ArrayList<>();
    private MyAdapter adapter;

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

        sendbtnButton = (Button) findViewById(R.id.sendbtn);
        listView = (ListView) findViewById(R.id.listview);

        getdataNews();
        inirView();
    }

    private void inirView() {

        adapter = new MyAdapter(this, list);
        listView.setAdapter(adapter);

        /**
         * 跳转至发布Activity
         */
        sendbtnButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                startActivity(new Intent(MainActivity.this, SendActivity.class));
            }
        });
        /**
         * 跳转至新闻详情Activity
         */
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
                //将标题等参数入传入 注意传入的键值与接收的一致
                Intent intent = new Intent(MainActivity.this, ShowMainActivity.class);
                intent.putExtra("title", list.get(arg2).get("title"));//键名
                intent.putExtra("content", list.get(arg2).get("content"));
                intent.putExtra("time", list.get(arg2).get("time"));
                intent.putExtra("username", list.get(arg2).get("username"));
                startActivity(intent);
            }
        });
        listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {

            public boolean onItemLongClick(AdapterView<?> arg0, View arg1,
                                           final int postion, long arg3) {
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setItems(new String[]{"修改", "删除"}, new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface arg0, int arg1) {
                        switch (arg1) {
                            case 0:
                                //单击修改的执行方法
                                Intent intent = new Intent(MainActivity.this, UpdateMainActivity.class);
                                intent.putExtra("title", list.get(postion).get("title"));
                                intent.putExtra("content", list.get(postion).get("content"));
                                intent.putExtra("nid", list.get(postion).get("nid"));
                                startActivity(intent);
                                break;
                            case 1:
                                //单击删除的执行方法
                                String sqlString = "delete from news where nid='" + list.get(postion).get("nid") + "'";
                                SQLiteDatabase db = Myapp.db.getWritableDatabase();
                                db.execSQL(sqlString);
                                Toast.makeText(MainActivity.this, "删除成功", Toast.LENGTH_LONG).show();
                                list.remove(postion);//移除list里面的数据
                                adapter.notifyDataSetChanged();//刷新数据库
                                break;
                        }
                    }
                });
                builder.show();
                return true;
            }
        });
    }

    /**
     * 获取所有新闻
     */
    private void getdataNews() {
        SQLiteDatabase dbDatabase = Myapp.db.getReadableDatabase();
        //查询新闻表
        String sqlString = "select * from news";
        Cursor cursor = dbDatabase.rawQuery(sqlString, null);
        while (cursor.moveToNext()) {
            Map<String, String> map = new HashMap<>();
            map.put("nid", cursor.getInt(cursor.getColumnIndex("nid")) + "");
            map.put("title", cursor.getString(cursor.getColumnIndex("title")));
            map.put("content", cursor.getString(cursor.getColumnIndex("content")));
            map.put("time", cursor.getString(cursor.getColumnIndex("newstime")));
            map.put("username", cursor.getString(cursor.getColumnIndex("username")));
            list.add(map);
        }
        //注意一定要关闭cursor
        cursor.close();
    }
}

package com.example.sqlitedemo;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import java.util.List;
import java.util.Map;

/**
 * Created by HLF on 2017/7/16.
 * 没做优化
 */

public class MyAdapter extends BaseAdapter {

    private List<Map<String, String>> list;

    private Context context;

    public MyAdapter(Context context, List<Map<String, String>> list) {
        this.context = context;
        this.list = list;
    }


    public int getCount() {
        return list.size();
    }

    public Object getItem(int arg0) {

        return getItemId(arg0);
    }

    public long getItemId(int arg0) {

        return arg0;
    }

    public View getView(int arg0, View v, ViewGroup arg2) {

        v = LayoutInflater.from(context).inflate(R.layout.listview, null);

        TextView timeTextView = (TextView) v.findViewById(R.id.item_time);
        TextView title = (TextView) v.findViewById(R.id.item_title);
        TextView username = (TextView) v.findViewById(R.id.item_username);

        timeTextView.setText(list.get(arg0).get("time"));
        title.setText(list.get(arg0).get("title"));
        username.setText(list.get(arg0).get("username"));

        return v;
    }
}

package com.example.sqlitedemo;

import android.app.Application;

/**
 * Created by HLF on 2017/7/16.
 */

public class Myapp extends Application {

    public static MyDateBasrHelp db;
    //名字可能很多地方会用到
    public static String username;

    @Override
    public void onCreate() {
        super.onCreate();
        //创建数据库
        db = new MyDateBasrHelp(getApplicationContext());
    }
}

package com.example.sqlitedemo;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

/**
 * Created by HLF on 2017/7/16.
 * 表的创建
 */

public class MyDateBasrHelp extends SQLiteOpenHelper {

    //数据库的名字
    final static String DBNAME = "mynews.db";
    //数据库的版本
    final static int version = 1;

    //, String name, SQLiteDatabase.CursorFactory factory, int version
    public MyDateBasrHelp(Context context) {
        super(context, DBNAME, null, version);
    }

    /**
     * 初始化表
     *
     * @param sqLiteDatabase
     */
    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        //创建表一张名为user的用户表 主键uid
        // 这里建议将创建表的语句用拼接的方式写 多张表会重复很多代码
        //参数有名字、密码、性别、年龄信息
        String userspl = "create table user(uid integer primary key autoincrement,username varchar,password varchar,sex varchar,age integer)";
        sqLiteDatabase.execSQL(userspl);

        //创建表一张名为news的新闻表 主键nid
        //参数有标题、内容、发布的时间、发布的作者名
        String newsql = "create table news(nid integer primary key autoincrement,title varchar,content varchar,newstime varchar,username varchar)";
        sqLiteDatabase.execSQL(newsql);
    }

    //表的更新
    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
}

package com.example.sqlitedemo;

import android.app.Activity;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

/**
 * 注册类
 */
public class RegistActivity extends Activity {

    private EditText username, password, sex, age;
    private Button regbtnButton;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_regeist);

        username = (EditText) findViewById(R.id.reg_username);
        password = (EditText) findViewById(R.id.reg_password);
        sex = (EditText) findViewById(R.id.reg_sex);
        age = (EditText) findViewById(R.id.reg_age);
        regbtnButton = (Button) findViewById(R.id.reg_ok_btn);

        regbtnButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View arg0) {
                String name = username.getText().toString();
                String pass = password.getText().toString();
                String se = sex.getText().toString();
                String ag = age.getText().toString();
                if (TextUtils.isEmpty(name)) {
                    Toast.makeText(RegistActivity.this, "用户名不能为空", Toast.LENGTH_LONG).show();
                    return;
                } else if (TextUtils.isEmpty(pass)) {
                    Toast.makeText(RegistActivity.this, "密码不能为空", Toast.LENGTH_LONG).show();
                    return;
                } else if (TextUtils.isEmpty(se)) {
                    Toast.makeText(RegistActivity.this, "性别不能为空", Toast.LENGTH_LONG).show();
                    return;
                } else if (TextUtils.isEmpty(ag)) {
                    Toast.makeText(RegistActivity.this, "年龄不能为空", Toast.LENGTH_LONG).show();
                    return;
                } else {
                    //插入你的数据到user表中数
                    SQLiteDatabase db = Myapp.db.getWritableDatabase();
                    //注意查入的顺序、字段名一定要一致 年龄注意是integer
                    String sql = "insert into user(username,password,sex,age) values" + "('" + name + "','" + pass + "','" + se + "','" + Integer.parseInt(ag) + "')";
                    db.execSQL(sql);//执行sql语句
                    Toast.makeText(RegistActivity.this, "注册成功", Toast.LENGTH_LONG).show();
                    finish();
                }
            }
        });
    }
}

package com.example.sqlitedemo;

import android.app.Activity;
import android.content.Intent;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.util.Calendar;

import static android.R.attr.start;
import static android.icu.lang.UCharacter.GraphemeClusterBreak.T;

/**
 * 发布新闻类
 */
public class SendActivity extends Activity implements OnClickListener {

    private EditText title, content;
    private Button btnButton;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_send);

        title = (EditText) findViewById(R.id.edit_title);
        content = (EditText) findViewById(R.id.edit_content);
        btnButton = (Button) findViewById(R.id.sendNews_btn);
        btnButton.setOnClickListener(this);
    }

    public void onClick(View arg0) {
        switch (arg0.getId()) {
            case R.id.sendNews_btn:
                String titl = title.getText().toString();
                String conten = content.getText().toString();
                if (TextUtils.isEmpty(titl)) {
                    Toast.makeText(SendActivity.this, "标题不能为空", Toast.LENGTH_LONG).show();
                    return;
                } else if (TextUtils.isEmpty(conten)) {
                    Toast.makeText(SendActivity.this, "内容不能为空", Toast.LENGTH_LONG).show();
                    return;
                } else {
                    String timString = getTime();//获取时间
                    SQLiteDatabase db = Myapp.db.getWritableDatabase();
                    //提交数据到news表中   插入4个参数
                    String sql = "insert into news(title,content,newstime,username) values " +
                            "('" + titl + "','" + conten + "','" + timString + "','" + Myapp.username + "')";
                    db.execSQL(sql);
                    startActivity(new Intent(SendActivity.this, MainActivity.class));
                    Toast.makeText(SendActivity.this, "发布成功", Toast.LENGTH_LONG).show();
                    finish();
                }
                break;
        }
    }

    /**
     * 获取系统时间
     */
    private String getTime() {
        Calendar calendar = Calendar.getInstance();
        String str = calendar.get(Calendar.YEAR) + "年" +
                (calendar.get(Calendar.MONTH) + 1) + "月" +
                calendar.get(Calendar.DAY_OF_MONTH) +
                "日" + calendar.get(Calendar.HOUR_OF_DAY) + "时" +
                calendar.get(Calendar.MINUTE) + "分" +
                calendar.get(Calendar.SECOND) + "秒";
        return str;
    }
}

package com.example.sqlitedemo;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.Window;
import android.view.WindowManager;
import android.widget.TextView;

/**
 * 新闻详情
 */
public class ShowMainActivity extends Activity {
private TextView title,content,time,nameTextView;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_show_main);

        title=(TextView) findViewById(R.id.info_title);
        content=(TextView) findViewById(R.id.info_content);
        time=(TextView) findViewById(R.id.info_time);
        nameTextView=(TextView) findViewById(R.id.info_author);
        Intent intent=getIntent();
        String titlestr=intent.getStringExtra("title");
        String contentstr=intent.getStringExtra("content");
        String timestr=intent.getStringExtra("time");
        String usernamestr=intent.getStringExtra("username");
        title.setText(titlestr);
        content.setText(contentstr);
        time.setText(timestr);
        nameTextView.setText(usernamestr);  
    }
}

package com.example.sqlitedemo;

import android.app.Activity;
import android.content.Intent;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

/**
 * 更新新闻类
 */
public class UpdateMainActivity extends Activity {

    private EditText title, content;
    private Button updatebutton;

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

        title = (EditText) findViewById(R.id.update_title);
        content = (EditText) findViewById(R.id.update_content);
        updatebutton = (Button) findViewById(R.id.updateNews_btn);

        Intent intent = getIntent();
        final String tit = intent.getStringExtra("title");
        final String cont = intent.getStringExtra("content");
        final String nid = intent.getStringExtra("nid");

        title.setText(tit);
        content.setText(cont);

        updatebutton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View arg0) {
                String strTit = title.getText().toString();
                String strCont = title.getText().toString();
                if (TextUtils.isEmpty(strTit)) {
                    Toast.makeText(UpdateMainActivity.this, "标题不能为空", Toast.LENGTH_LONG).show();
                    return;
                } else if (TextUtils.isEmpty(strCont)) {
                    Toast.makeText(UpdateMainActivity.this, "内容不能为空", Toast.LENGTH_LONG).show();
                    return;
                }
                //更新新闻表
                String sql = "update news set title='" + strTit + "',content='" + strCont + "'where nid='" + nid + "'";
                SQLiteDatabase db = Myapp.db.getWritableDatabase();
                db.execSQL(sql);
                Toast.makeText(UpdateMainActivity.this, "修改成功", Toast.LENGTH_LONG).show();
                startActivity(new Intent(UpdateMainActivity.this, MainActivity.class));
                finish();
            }
        });
    }
}

Step 5：两个资源文件

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
    <corners android:radius="5dp"/>

    <stroke android:width="3dp"
        android:color="#008AD4"/>
        <solid  android:color="#008AD4"/>
</shape>

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
    <!--设置圆角半径  -->
    <corners 
        android:radius="5dp"/>
    <!-- 设置边框的厚度以及边框的颜色 -->
    <stroke android:width="2dp" 
            android:color="#666"/>
</shape>

数据库有缓存，修改代码没效果可以先清除缓存试试！！！