android查询数据库中新闻表的信息并将所有信息显示在界面的listview上 所有的相关代码

好的，以下是一个简单的 Android 查询数据库中新闻表的信息并将所有信息显示在界面的 ListView 上的代码示例：

首先，在你的 Android 项目中创建一个数据库帮助类 NewsDBHelper.java，用于创建和管理数据库：

public class NewsDBHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "news.db";
    private static final int DATABASE_VERSION = 1;

    public NewsDBHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE IF NOT EXISTS news ("
                + "id INTEGER PRIMARY KEY AUTOINCREMENT,"
                + "title TEXT,"
                + "content TEXT,"
                + "date TEXT)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS news");
        onCreate(db);
    }
}

接下来，在你的 Activity 中，你可以使用以下代码查询数据库中的新闻信息，并将它们显示在 ListView 中：

public class MainActivity extends AppCompatActivity {
    private ListView mListView;
    private NewsDBHelper mDBHelper;
    private SQLiteDatabase mDatabase;

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

        mListView = findViewById(R.id.listView);
        mDBHelper = new NewsDBHelper(this);
        mDatabase = mDBHelper.getWritableDatabase();

        Cursor cursor = mDatabase.query("news", null, null, null, null, null, null);
        List<News> newsList = new ArrayList<>();
        while (cursor.moveToNext()) {
            int id = cursor.getInt(cursor.getColumnIndex("id"));
            String title = cursor.getString(cursor.getColumnIndex("title"));
            String content = cursor.getString(cursor.getColumnIndex("content"));
            String date = cursor.getString(cursor.getColumnIndex("date"));
            newsList.add(new News(id, title, content, date));
        }
        cursor.close();

        NewsAdapter adapter = new NewsAdapter(this, newsList);
        mListView.setAdapter(adapter);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        mDatabase.close();
        mDBHelper.close();
    }

    private static class NewsAdapter extends ArrayAdapter<News> {
        private LayoutInflater mInflater;

        public NewsAdapter(Context context, List<News> newsList) {
            super(context, 0, newsList);
            mInflater = LayoutInflater.from(context);
        }

        @NonNull
        @Override
        public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
            if (convertView == null) {
                convertView = mInflater.inflate(R.layout.list_item_news, parent, false);
            }

            News news = getItem(position);

            TextView titleView = convertView.findViewById(R.id.title);
            TextView contentView = convertView.findViewById(R.id.content);
            TextView dateView = convertView.findViewById(R.id.date);

            titleView.setText(news.getTitle());
            contentView.setText(news.getContent());
            dateView.setText(news.getDate());

            return convertView;
        }
    }
}

其中，News.java 是一个简单的 Java Bean 类，用于存储新闻数据：

public class News {
    private int id;
    private String title;
    private String content;
    private String date;

    public News(int id, String title, String content, String date) {
        this.id = id;
        this.title = title;
        this.content = content;
        this.date = date;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }
}

最后，你需要在你的布局文件中定义 ListView 和每个列表项的布局：

activity_main.xml：

<?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">

   <ListView
       android:id="@+id/listView"
       android:layout_width="match_parent"
       android:layout_height="0dp"
       android:layout_weight="1" />

</LinearLayout>

list_item_news.xml：

<?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="wrap_content"
   android:orientation="vertical"
   android:padding="16dp">

   <TextView
       android:id="@+id/title"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:textStyle="bold"
       android:textSize="18sp" />

   <TextView
       android:id="@+id/content"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:layout_marginTop="8dp" />

   <TextView
       android:id="@+id/date"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:layout_marginTop="8dp"
       android:textColor="#999999" />

</LinearLayout>

以上就是一个简单的 Android 查询数据库中新闻表的信息并将所有信息显示在界面的 ListView 上的代码示例，希望对你有所帮助。