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我是这种编程的新手。我认为我错过了一些东西，但我不知道我错过了什么。运行模拟器时我没有收到任何错误，并且我能够验证数据是否正在进入数据库。我只是不能让它显示在列表中。列表显示但没有数据。请帮忙！

显示课程.java

package com.greygoosefarmpa.fencecoursebuilder;
import java.util.ArrayList;
import java.util.List;

import com.google.android.maps.MapActivity;
import com.greygoosefarmpa.db.courseDBOpenHelper;
import com.greygoosefarmpa.db.courseDataSource;
import com.greygoosefarmpa.model.Course;

import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.TextView;


public class displayCourse extends MapActivity {

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


TextView dc = (TextView) findViewById(R.id.displayCourses);

courseDataSource datasource = new courseDataSource(this);
datasource.open();




List<Course> course = datasource.findAll();

ArrayAdapter<Course> adapter = new ArrayAdapter<Course>(this, android.R.layout.simple_list_item_1, course);
setListAdapter(adapter);
//datasource.close();

}



private void  setListAdapter(ArrayAdapter<Course> adapter) {
    // TODO Auto-generated method stub

}



@Override
protected boolean isRouteDisplayed() {
    // TODO Auto-generated method stub
    return false;
}}

courseDataSource.java

package com.greygoosefarmpa.db;

import java.util.ArrayList;
import java.util.List;

import com.greygoosefarmpa.model.Course;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.*;
import android.util.Log;

public class courseDataSource {

public static final String LOGTAG = "courseDatabase";

SQLiteOpenHelper dbhelper;
SQLiteDatabase database;

private static final String[] allColumns = {
        courseDBOpenHelper.COLUMN_ALOCATION,
        courseDBOpenHelper.COLUMN_BLOCATION,
        courseDBOpenHelper.COLUMN_COURSENAME,
        courseDBOpenHelper.COLUMN_FENCENAME,
        courseDBOpenHelper.COLUMN_ID    };


public courseDataSource(Context context) {
    dbhelper = new courseDBOpenHelper(context);
    database = dbhelper.getWritableDatabase();
}

public void open(){
    Log.i(LOGTAG, "database open");
    database = dbhelper.getWritableDatabase();
}

public void close(){
    Log.i(LOGTAG, "database closed");
    dbhelper.close();
}

public Course create(Course course) {
    ContentValues values = new ContentValues();
    values.put(courseDBOpenHelper.COLUMN_COURSENAME, course.getcourseid());
    values.put(courseDBOpenHelper.COLUMN_FENCENAME, course.getcoursename());
    values.put(courseDBOpenHelper.COLUMN_ALOCATION, course.getAlocation());
    values.put(courseDBOpenHelper.COLUMN_BLOCATION, course.getBlocation());
    long insertid = database.insert(courseDBOpenHelper.TABLE_COURSES, null, values);
    course.setcourseid(insertid);
    return course;
}

public List<Course> findAll() {
    List<Course> courses = new ArrayList<Course>();

    Cursor cursor = database.query(courseDBOpenHelper.TABLE_COURSES, allColumns, null, null, null, null, null);
            Log.i(LOGTAG, "returned " + cursor.getCount() + " rows");
            cursor.moveToFirst();
            while(!cursor.isAfterLast()) {
            cursorToCourse(cursor);
            cursor.moveToNext();
            }
            cursor.close();
            return courses;
        }




private Course cursorToCourse(Cursor cursor) {
    Course course = new Course();
    course.setcourseid(cursor.getLong(cursor.getColumnIndex(courseDBOpenHelper.COLUMN_ID)));
    course.setAlocation(cursor.getString(cursor.getColumnIndex(courseDBOpenHelper.COLUMN_ALOCATION)));
    course.setBlocation(cursor.getString(cursor.getColumnIndex(courseDBOpenHelper.COLUMN_BLOCATION)));
    course.setcoursename(cursor.getString(cursor.getColumnIndex(courseDBOpenHelper.COLUMN_COURSENAME)));
    course.setfencename(cursor.getString(cursor.getColumnIndex(courseDBOpenHelper.COLUMN_FENCENAME)));
    return course;
}
}

课程.java

package com.greygoosefarmpa.model;

import java.text.NumberFormat;

import android.R.string;
import android.view.View;

public class Course {
private long courseid;
private String coursename;
private String fencename;
private String Alocation;
private String Blocation;


public long getcourseid(){
    return courseid;
}

public void setcourseid(long courseid) {
    this.courseid = courseid;
}

public String getcoursename(){
    return coursename;
}

public void setcoursename(String string){
    this.coursename = string;
}

public String getfencename(){
    return fencename;
}

public void setfencename(String fencename){
    this.fencename = fencename;
}

public String getAlocation(){
    return Alocation;
}

public void setAlocation(String string){
    this.Alocation = string;
}

public String getBlocation(){
    return Blocation;
}

public void setBlocation(String string){
    this.Blocation = string;
}


}

courseDBOpenHelper.java

package com.greygoosefarmpa.db;

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

public class courseDBOpenHelper extends SQLiteOpenHelper {

private static final String LOGTAG = "courseDatabase";

private static final String DATABASE_NAME = "courses.db";
private static final int DATABASE_VERSION = 1;

public static final String TABLE_COURSES = "courses";
public static final String COLUMN_ID = "coursesID";
public static final String COLUMN_COURSENAME = "coursename";
public static final String COLUMN_FENCENAME = "fencename";
public static final String COLUMN_ALOCATION = "alocation";
public static final String COLUMN_BLOCATION = "blocation";

private static final String TABLE_CREATE = 
        "CREATE TABLE " + TABLE_COURSES + " (" +
        COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
        COLUMN_COURSENAME + " TEXT, " +
        COLUMN_FENCENAME + " TEXT, " +
        COLUMN_ALOCATION + " NUMERIC, " +
        COLUMN_BLOCATION +  " NUMBERIC " +
        ")";

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

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(TABLE_CREATE);
    Log.i(LOGTAG, "table created");
}

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

}

}
4

1 回答 1

1

尝试将您的 while 语句更改为：

cursor.moveToFirst();
while(!cursor.isAfterLast()) {
    ...operations...
    cursor.moveToNext();
}

这就是我一直进行光标迭代的方式。您可能想考虑创建另一个函数来创建给定光标的课程，就像这样。

private Course cursorToCourse(Cursor cursor) {
    Course course = new Course();
    course.setcourseid(cursor.getLong(cursor.getColumnIndex(courseDBOpenHelper.COLUMN_ID)));
    course.setAlocation(cursor.getString(cursor.getColumnIndex(courseDBOpenHelper.COLUMN_ALOCATION)));
    course.setBlocation(cursor.getString(cursor.getColumnIndex(courseDBOpenHelper.COLUMN_BLOCATION)));
    course.setcoursename(cursor.getString(cursor.getColumnIndex(courseDBOpenHelper.COLUMN_COURSENAME)));
    course.setfencename(cursor.getString(cursor.getColumnIndex(courseDBOpenHelper.COLUMN_FENCENAME)));
    return course;
}

只是为了清理一下，而且您可以轻松地重复使用它。

哦，快！在返回之前不要忘记在 findAll() 的末尾关闭光标。

cursor.close();
于 2013-03-25T21:00:30.847 回答