Question

我正在尝试设置一个包含日期对象的日历（来自我的日期课程）。如果循环到达下个月，它将进入另一个具有其他条件的for循环。这些条件似乎不对，因为内循环让我以相反的顺序回到了日子，我无法弄清楚什么是错的。

这是活动的完整代码（参见循环所在的listOfDays（）方法）：

package com.mobilecartography.tudresdenspeechorganiser;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.Locale;

import org.joda.time.DateTime;

import android.app.ListActivity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.widget.ExpandableListView;

import com.mobilecartography.tudresdenspeechorganiser.R;
import com.mobilecartography.tudresdenspeechorganiser.DatabaseHelper;

public class MainActivity extends ListActivity {

  ArrayList<CurrentDay> currentweek = new ArrayList<CurrentDay>();

  SQLiteDatabase database = null;
  Cursor dbCursor;
  DatabaseHelper dbHelper;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    this.dbHelper = new DatabaseHelper(this);
    try {
        setListofDays();
    } catch (ParseException e) {
        e.printStackTrace();
    }
    ExpandableListView listView = (ExpandableListView) findViewById(R.id.listView);
    MyExpandableListAdapter adapter = new MyExpandableListAdapter(this,
        currentweek);
    listView.setAdapter(adapter);
  }



//fill list with 8 entrys with dates (based on joda time and java.util.date) for the next 8 days, for 
//each days query presentations for that specific day from sql database  
  public void setListofDays() throws ParseException {
      DateTime cal = new DateTime();    //jodatime calendar for todays date
      CurrentDay day = null;
      int maxDay = cal.dayOfMonth().getMaximumValue();
      int currentday = cal.getDayOfMonth();
      int currentmonth; 
      int currentyear = cal.getYear();

      for (int i = 0; i < 20; i++){
        //check if day of iteration is already in the next month
        if (currentday+i > maxDay){  

            for (int h = 0; h < 20 - i; h++){       

                    currentmonth = cal.getMonthOfYear()+1;

                    // get name of day of week from 2nd calendar
                    String dateString = String.format("%d-%d-%d", currentyear, currentmonth, h);
                    Date date = new SimpleDateFormat("yyyy-MM-dd").parse(dateString);
                    String dayofweek = new SimpleDateFormat("EEEE", Locale.GERMAN).format(date);

                    day = new CurrentDay(1+h, dayofweek, currentmonth, currentyear);
                    }
                }           
        else {
            currentmonth = cal.getMonthOfYear();

            // get name of day of week from 2nd calendar
            String dateString = String.format("%d-%d-%d", currentyear, currentmonth, currentday+i);
            Date date = new SimpleDateFormat("yyyy-MM-dd").parse(dateString);
            String dayofweek = new SimpleDateFormat("EEEE", Locale.GERMAN).format(date);

            day = new CurrentDay(currentday+i, dayofweek, currentmonth, currentyear);
        }

        //reference dbHelper instances of mainactivity and currentday object
        day.dbHelper = this.dbHelper;

        //load presentations that take place on that day
        try {
            day.loadPresentations();
            } catch (Exception e) {
                e.printStackTrace();
            }
        currentweek.add(day);       //add day object to list of days
        }
    }
}

这是当前的课程：

    package com.mobilecartography.tudresdenspeechorganiser;

//This class is used for creating day objects with attached data from an sql database
//that are used in the calendar of the main activity

import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import com.mobilecartography.tudresdenspeechorganiser.DatabaseHelper;

public class CurrentDay {

    public int day;
    public int month;
    public int year;
    public String dayofweek;
    DatabaseHelper dbHelper;
    public List<String> children;
    SQLiteDatabase database = null;
    Cursor dbCursor;

    //constructor for day object which consists out of a day, the name of the weekday, the month and the year
    public CurrentDay(int day, String dayofweek, int month, int year) {
        this.day = day;
        this.month = month;
        this.year = year;
        this.dayofweek = dayofweek;
    }

    //query titles of the presentations from sql database for specific date
    public void loadPresentations() {

            try {
                dbHelper.createDataBase();
            } catch (IOException ioe) {
        }

        try {
            //get date from day object and transfrom it into sql date
            SimpleDateFormat formater = new SimpleDateFormat("yyyy-MM-dd");  
            java.util.Date parsedUtilDate;
            String date_string = this.year+"-"+this.month+"-"+this.day;
            parsedUtilDate = formater.parse(date_string);
            java.sql.Date sqlDate = new java.sql.Date(parsedUtilDate.getTime());  

            children = new ArrayList<String>();

            database = dbHelper.getDataBase();

            //get titles of table if they have the date of the day object
            dbCursor = database.rawQuery("SELECT Titel FROM presentations WHERE Datum = '" +sqlDate +"'",
                    null);

            dbCursor.moveToFirst();
            int index = dbCursor.getColumnIndex("Titel");
            while (!dbCursor.isAfterLast()) {
                String record = dbCursor.getString(index);
                children.add(record);
                dbCursor.moveToNext();
            }

        } 
            catch (ParseException e) {
            e.printStackTrace();
        }  
        finally {
            if (database != null) {
                dbHelper.close();
            }
        }
    }

    //get description of day object as shown in child view of expandable list
    public String getName() {
        return this.dayofweek+", "+Integer.toString(this.day)+"."+Integer.toString(this.month)+".";
    }


}

因此，而不是向上计数1 + h向后计数：

它应该如何：1,2,3,4,5,6,7,8

如何显示：8,7,6,5,4,3,2,1

我是Android和编程的初学者，我猜有更好的方法来创建日历，但我只是想知道这里有什么错误，所以我的错误在哪里？

Answer 1

好的，我发现了问题：我将addDay（）和loadPresentations（）方法添加到h循环的末尾，并在for循环的末尾添加了一个break：

for (int i = 0; i < 20; i++){
        //check if day of iteration is already in the next month
        if (currentday+i > maxDay){  

            for (int h = 1; h < 20-i; h++){     
                    currentmonth = cal.getMonthOfYear()+1;

                    // get name of day of week
                    String dateString = String.format("%d-%d-%d", currentyear, currentmonth, h);
                    Date date = new SimpleDateFormat("yyyy-MM-dd").parse(dateString);
                    String dayofweek = new SimpleDateFormat("EEEE", Locale.GERMAN).format(date);

                    day = new CurrentDay(h, dayofweek, currentmonth, currentyear);

                    //reference dbHelper instances of mainactivity and currentday object
                    day.dbHelper = this.dbHelper;

                    //load presentations that take place on that day
                    try {
                        day.loadPresentations();
                        } catch (Exception e) {
                            e.printStackTrace();
                            }
                    currentweek.add(day);       //add day object with attached presentations to list of days
                    }
                }           
        else {
            currentmonth = cal.getMonthOfYear();

            // get name of day of week
            String dateString = String.format("%d-%d-%d", currentyear, currentmonth, currentday+i);
            Date date = new SimpleDateFormat("yyyy-MM-dd").parse(dateString);
            String dayofweek = new SimpleDateFormat("EEEE", Locale.GERMAN).format(date);

            day = new CurrentDay(currentday+i, dayofweek, currentmonth, currentyear);

            //reference dbHelper instances of mainactivity and currentday object
            day.dbHelper = this.dbHelper;

            //load presentations that take place on that day
            try {
                day.loadPresentations();
                } catch (Exception e) {
                    e.printStackTrace();
                    }
            currentweek.add(day); //add day object with attached presentations to list of days
            }

        if (currentday+i > maxDay){
                break;
            }
        }

Android：for-loop提供反转值

1 个答案: