我想重用ListAC ListActivity中的几种方法,并希望将它们放在单独的类中(如果可能的话？).我将有数十个ListView活动(ListActivities,即：ListAD,ListTCDS,listSFAR等),它们将调用与该活动中完全相同的这些方法,但唯一的变化是“ Cursor databaseCursor”(即每个ListActivity的表名).我计划将这些类和相关类放入应用程序(即com.myCompany.myApp.AC)各自的包中.另外,不包含这些活动,查询的“ ORDER BY”也需要多个课程(即：“ …’列表’ASC | DESC”,“ …’标题’ASC | DESC”等). B4的游标被调用,我也有检查ExternalStorageState的方法.我获得了LeffelMania(THNX！)的类StorageStateChecker(请参见下文),用于重用ExternalStorageState,即使在下面的代码中未实现,我仍想使用它.我决定退后一步*以重新考虑这一点(我搞砸了自己-大声笑),并使你们和gal更容易阅读代码.

如您所见,这将导致大量不必要的冗余和设备上的字节空间.我需要压缩设备上所有可能的空间,因为此应用程序将是这些设备用户的唯一目的(如果项目向前发展-大声笑).

因此,我需要一种方法,可以通过单独的类调用这些方法,以尽可能地减少编写这些方法和适配器的方式.关于建议,方法,方法和代码的任何帮助对我学习Java / Android都将非常有帮助.日Thnx！

*该职位是相关的,并且从HERE和HERE继续.

更新：完成的类在REVISED块中.感谢所有对我有帮助的人,现在我对班级有了更好的了解.方法用法.

ListAC活动：

public class ListAC extends ListActivity {
/**
 * -- Called when the activity is first created
 * ===================================================================
 */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.list_view2);

    activityTitle = (TextView) findViewById(R.id.titleBarTitle);
    activityTitle.setText("ADVISORY CIRCULATORS");

    storageState();
    searchList();
    nextActivity(); 
}

/**
 * -- Check to See if the SD Card is Mounted & Loads Default List Order
 * ======================================================================
 **/
private void storageState() {
    if (android.os.Environment.getExternalStorageState().equals(
            android.os.Environment.MEDIA_MOUNTED)) {

        orderASC_Label();// Loads the list

    } else if (android.os.Environment.getExternalStorageState().equals(
            android.os.Environment.MEDIA_UNMOUNTED)) {
        Alerts.sdCardMissing(this);
    }
}

/**
 * -- Default List Order (Ascending)
 * =====================================================================
 **/
public void orderASC_Label() {
    Cursor databaseCursor = db.rawQuery(
            "SELECT * FROM AC_list ORDER BY `label` ASC", null);

    Adapter_AC databaseListAdapter = new Adapter_AC(this,
            R.layout.list_item, databaseCursor, new String[] { "label",
                    "title", "description", "gotoURL" }, new int[] {
                    R.id.label, R.id.listTitle, R.id.caption, R.id.dummy });

    databaseListAdapter.notifyDataSetChanged();
    this.setListAdapter(databaseListAdapter);
}

/**
 * -- Starts the Next Activity
 * =====================================================================
 **/
public void nextActivity() {

    final ListView lv = getListView();
    lv.setTextFilterEnabled(true);
    lv.setClickable(true);

    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> a, View v, int pos, long id) {

            String url = "";
            TextView tv = (TextView) v.findViewById(R.id.dummy);
            url = (String) tv.getTag();

            String lbl = "";
            TextView tv2 = (TextView) v.findViewById(R.id.label);
            lbl = (String) tv2.getTag();

            Intent i = new Intent(List_AC.this, DocView.class);
            i.putExtra("url", url);
            i.putExtra("label", lbl);
            startActivity(i);
        }
    });
}

/**
 * -- Dispatched when the Menu-Key is presses
 * =====================================================================
 **/
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_MENU) {
        Intent i = new Intent(List_AC.this, DashBoard.class);
        startActivity(i);
    }
    return super.onKeyDown(keyCode, event);
}

/**
 * -- Local Variables
 * =====================================================================
 **/
protected TextView activityTitle;
boolean mExternalStorageAvailable = false;
boolean mExternalStorageWriteable = false;
String extStorageDirectory = Environment.getExternalStorageDirectory()
        .toString();
File dbfile = new File(extStorageDirectory
        + "/XXX/xxx/dB/xxx.db");
SQLiteDatabase db = SQLiteDatabase.openOrCreateDatabase(dbfile, null);

/** ======================= END ==================================== **/
}

我的适配器(AdaperAC)：

public class AdapterAC extends SimpleCursorAdapter {


static Cursor dataCursor;
private LayoutInflater mInflater;

public Adapter_AC(Context context, int layout, Cursor dataCursor,
        String[] from, int[] to) {
    super(context, layout, dataCursor, from, to);
    this.dataCursor = dataCursor;
    mInflater = LayoutInflater.from(context);
}

public View getView(int position, View convertView, ViewGroup parent) {

    ViewHolder holder;

    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.list_item, null);

        holder = new ViewHolder();
        holder.text1 = (TextView) convertView.findViewById(R.id.label);
        holder.text2 = (TextView) convertView.findViewById(R.id.listTitle);
        holder.text3 = (TextView) convertView.findViewById(R.id.caption);
        holder.text4 = (TextView) convertView.findViewById(R.id.dummy);

        holder.text4.setVisibility(View.GONE);

        convertView.setTag(holder);

    } else {
        holder = (ViewHolder) convertView.getTag();
    }

    dataCursor.moveToPosition(position);

    int label_index = dataCursor.getColumnIndex("label");
    String label = dataCursor.getString(label_index);

    int title_index = dataCursor.getColumnIndex("title");
    String title = dataCursor.getString(title_index);

    int description_index = dataCursor.getColumnIndex("description");
    String description = dataCursor.getString(description_index);

    int goto_index = dataCursor.getColumnIndex("gotoURL");
    String gotoURL = dataCursor.getString(goto_index);

    holder.text1.setText(label);
    holder.text1.setTag(label);
    holder.text2.setText(title);
    holder.text3.setText(description);
    //holder.text4.setText(gotoURL);
    holder.text4.setTag(gotoURL);

    return convertView;
}

static class ViewHolder {
    TextView text1;
    TextView text2;
    TextView text3;
    TextView text4;
}

}

修改为：

public class QueryDisplay extends ListActivity {

protected TextView activityTitle;

boolean mExternalStorageAvailable = false;
boolean mExternalStorageWriteable = false;

String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
File dbfile = new File(extStorageDirectory + "/myComp/myApp/dB/myApp.db");
SQLiteDatabase db = SQLiteDatabase.openOrCreateDatabase(dbfile, null);

private static final String QUERY_KEY = "QUERY_KEY";

/**
 * -- Called when the activity is first created
 * ===================================================================
 */
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.list_view2);

    Bundle extras = getIntent().getExtras();

    String q = null;
    if (extras != null) {

        q = extras.getString(QUERY_KEY);
        Log.i("tag", "getting extras" + extras);
    }

    reloadQuery(q);
}

public void reloadQuery(String q) {

    Log.i("tag", "reloadQuery");

    if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {

        Cursor c = db.rawQuery(q, null);
        setListAdapter(new QueryAdapter(this, c));
        db.close();

    }else {
        Alerts.sdCardMissing(this);
    }
}

private class QueryAdapter extends CursorAdapter {

    public QueryAdapter(Context context, Cursor c) {
        super(context, c);
        LayoutInflater.from(context);
    }

    @Override
    public void bindView(View v, Context context, Cursor c) {

            int tvLabel = c.getColumnIndexOrThrow("label");
            String label = c.getString(tvLabel);
            TextView labelTxt = (TextView) v.findViewById(R.id.label);

            if (labelTxt != null) {
                labelTxt.setText("(" + label + ")");
            }

            int tvTitle = c.getColumnIndexOrThrow("title");
            String title = c.getString(tvTitle);
            TextView titleTxt = (TextView) v.findViewById(R.id.listTitle);

            if (titleTxt != null) {
                titleTxt.setText(title);
            }

            int tvDescription = c.getColumnIndexOrThrow("description");
            String description = c.getString(tvDescription);
            TextView descriptionTxt = (TextView) v.findViewById(R.id.caption);

            if (descriptionTxt != null) {
                descriptionTxt.setText(description);
            }

            int tvGoto= c.getColumnIndexOrThrow("gotoURL");
            String gotoURL = c.getString(tvGoto);
            TextView gotoTxt = (TextView) v.findViewById(R.id.dummy);

            if (gotoTxt != null) {
                gotoTxt.setText(gotoURL);
            }

            gotoTxt.setVisibility(View.GONE);
            v.setTag(tvGoto);
    }

    @Override
    public View newView(Context context, Cursor c, ViewGroup parent) {

        final View v = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);
        return v;
    }
}
}

…以及如何致电&注入查询：

OnClickListener myClickListener = new OnClickListener() {
    @Override
    public void onClick(View v) {
        if (v == myBtn) {

            String queryKey = "SELECT * FROM a_tablet ORDER BY `column` ASC";
            Intent i = new Intent(CurrentClass.this,QueryDisplay.class);
            i.putExtra("QUERY_KEY", queryKey);
            startActivity(i);
            }

解决方法:

似乎您正在做大量的额外工作,只是为Cursor提供了许多不同的查询选项.

为什么不想要一个带有一个CursorAdapter的ListActivity,而只想在启动Activity时将查询放在Intent中呢？

我将处理一个小的代码示例,并将其发布在此处进行编辑,但是您似乎对此确实过于考虑.您要做的就是在ListView中显示查询的结果.唯一更改的是查询.重用其他所有内容.

代码示例：

public class QueryDisplay extends ListActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        Bundle extras = getIntent().getExtras();

        if (extras != null)
            reloadQuery(extras.getString(QUERY_KEY));

    }

    private void reloadQuery(query) {
        // Build your Cursor here.
        setAdapter(new QueryAdapter(this, cursor));
    }

    private class QueryAdapter extends CursorAdapter {

        @Override
        public void bindView(View view, Context context, Cursor cursor) {
            // Set up your view here
        }

        @Override
        public View newView(Context context, Cursor cursor, ViewGroup parent) {
            // Create your new view here
            final View view = LayoutInflator.from(context).inflate(R.layout.your_query_list_item_layout, parent, false); 
            return view;
        }
    }
}

从字面上看,这是您需要的所有代码(以及用于自定义Views和构建Cursor的填充).每当您需要更改查询时,只需调用reloadQuery(String query)即可进行设置.