我有2个表，公司表（用于存储登录信息）和分配（用于存储分配详细信息）。
企业表中的列：id（主键自动递增），uname，密码。
没有从用户那里获得ID。
分配表中的列：Assignment_topic，assignment_content，total_marks，id（外键），id_assignment（主键自动递增）。
信息流：
1.登录用户->除了检查是否有有效用户外，还要初始化id（1000）并返回它（searchId（）方法）。
2. UI输入来自用户的分配详细信息-> BackgroundTask ---> insertAssignment方法。
问题：我无法通过从公司表中检索id（主键）在分配表中插入id（FOREIGN KEY）。有关列显示为空。
尝试了以下内容：
如您在DatabaseHelper类中所看到的，我尝试了外键，但是它不起作用，因此将其删除。
除了上述之外，我尝试通过getter和setter获取id，能够做到一定程度，但不知道数据在哪里中断。
由于我是Android新手，如果你们可以帮助我解决此问题，那将是很棒的。
如果您需要我提供的进一步信息，请告诉我。
以下是必要的代码。
Insert_assignment类：
public void SubmitData(View view) {
String topic_assign = topic.getText().toString();
String topic_content_assign = topic_content.getText().toString();
String total_marks = t_marks.getText().toString();
String id = loginInfo.getId();
Log.e("assignment_id:",id);
BackgroundTask backgroundTask = new BackgroundTask(this);
backgroundTask.execute("add_assignment", topic_assign, topic_content_assign, total_marks,id);
}
BackgroundTask类：
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.ListView;
import android.widget.Toast;
public class BackgroundTask extends AsyncTask<String, Teacher_Assignment, String> {
private static final String TAG = " Background task";
LoginInfo loginInfo = new LoginInfo();
Activity activity;
ListView listView;
AssignmentAdapter assignmentAdapter;
Teacher_Assignment teacher_assignment = new Teacher_Assignment();
private Context context;
BackgroundTask(Context context)
{
this.context = context;
activity = (Activity)context;
}
@Override
protected String doInBackground(String... params) {
String method = params[0];
DatabaseHelper databaseHelper = new DatabaseHelper(context);
if(method.equals("add_assignment")) {
String topic_assignment = params[1];
String topic_content = params[2];
String total_marks = params[3];
String id = params[4];
SQLiteDatabase db = databaseHelper.getWritableDatabase();
databaseHelper.insertAssignment(db,topic_assignment,topic_content,total_marks, id);
Log.d(TAG,"inserted successfully");
} else if(method.equals("get_info")) {
listView = (ListView) activity.findViewById(R.id.list_assignment);
//DatabaseHelper databaseHelper = new DatabaseHelper(context);
SQLiteDatabase db = databaseHelper.getReadableDatabase();
Cursor cursor = databaseHelper.getInformation(db);
assignmentAdapter = new AssignmentAdapter(context, R.layout.activity_assignment_page_recycle_view);
String assignment_content;
while(cursor.moveToNext()){
assignment_content = cursor.getString(cursor.getColumnIndex(teacher_assignment.Assignment_content));
Teacher_Assignment teacher_assignment = new Teacher_Assignment(assignment_content);
publishProgress(teacher_assignment);
}
return "get_info";
}
return "One row inserted";
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected void onPostExecute(String result) {
if (result.equals("get_info")) {
listView.setAdapter(assignmentAdapter);
} else {
Toast.makeText(context, result, Toast.LENGTH_LONG).show();
}
}
protected void onProgressUpdate(Assignment_Page... values) {
assignmentAdapter.add(values[2]);
}
}
DatabaseHelper类：
package com.example.education;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.nfc.Tag;
import android.util.Log;
class DatabaseHelper extends SQLiteOpenHelper {
LoginInfo loginInfo = new LoginInfo();
Teacher_Assignment assign1 = new Teacher_Assignment();
//Login table
private static final int DATABASE_VERSION = 41;
private static final String DATABASE_NAME = "userInfo.db";
private static final String TABLE_NAME = "corporate";
private static final String COLUMN_ID = "id";
private static final String COLUMN_UNAME = "uname";
private static final String COLUMN_PASSWORD = "password";
private static final String TABLE_ASSIGNMENT = "assignment";
//private static final String COLUMN_ID_ASSIGNMENT = "user_id";
private static final String ASSIGNMENT_TOPIC = "assignment_topic";
//private static final String COLUMN_NAME = COLUMN_UNAME;
private static final String ASSIGNMENT_CONTENT = "assignment_content";
private static final String ASSIGNMENT_TOTAL_MARKS = "total_marks";
private static final String ID_COLUMN_ASSIGNMENT = "id_assignment";
private static final String TABLE_STUDENT_SELECTION = "student_selection";
private static final String COLUMN_STUDENT_ID = "student_id";
private static final String COLUMN_CLASS_SEC = "class_sec";
private static final String COLUMN_STUDENT_NAME = "name";
private static final String COLUMN_TOTAL_MARKS = "total_marks";
private static final String COLUMN_STUDENT_MARKS = "student_score";
SQLiteDatabase db;
private static final String CREATE_TABLE = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME + "("
+ COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + COLUMN_UNAME + " TEXT NOT NULL, " + COLUMN_PASSWORD + " TEXT NOT NULL " + ")";
private static final String CREATE_ASSIGNMENT_TABLE = "CREATE TABLE IF NOT EXISTS " + TABLE_ASSIGNMENT + "("
+ ASSIGNMENT_TOPIC + " TEXT NOT NULL, " + ASSIGNMENT_CONTENT + " TEXT NOT NULL, "
+ ASSIGNMENT_TOTAL_MARKS + " TEXT NOT NULL, "
+ ID_COLUMN_ASSIGNMENT + " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ COLUMN_ID + " TEXT " + ")";
//+ " FOREIGN KEY(" + COLUMN_ID + ") REFERENCES " + TABLE_NAME + " (id) "
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public void insertData() {
db = this.getWritableDatabase();
ContentValues content = new ContentValues();
content.put(COLUMN_ID,1000);
content.put(COLUMN_UNAME, "akhil");
content.put(COLUMN_PASSWORD,"admin");
db.insert(TABLE_NAME, null, content);
db.close();
}
public String insertAssignment(SQLiteDatabase db,String topic, String assignment_content, String total_marks, String id) {
db = this.getWritableDatabase();
ContentValues content1 = new ContentValues();
//id = searchId(COLUMN_UNAME);
content1.put(ASSIGNMENT_TOPIC, topic);
content1.put(ASSIGNMENT_CONTENT,assignment_content);
content1.put(ASSIGNMENT_TOTAL_MARKS,total_marks);
content1.put(COLUMN_ID, loginInfo.getId());
db.insert(TABLE_ASSIGNMENT, null, content1);
db.close();
return topic;
}
数据库截图：
java大神给出的解决方案
id值来自在BackgroundTask中初始化的loginInfo实例：
class DatabaseHelper extends SQLiteOpenHelper {
LoginInfo loginInfo = new LoginInfo();
如果id是通过//id = searchId(COLUMN_UNAME);获得的，请检查searchId方法。
我正在使用Retrofit来获取JSON答复。这是我实施的一部分-@GET("/api/report/list") Observable<Bills> listBill(@Query("employee_id") String employeeID); 而条例草案类是-public static class…
如何在JAVA中传递以逗号分隔的值作为函数参数的字符串 - java我有一个可以接受任何数量的INTEGER参数的方法：pages(int,int...)此方法是选择PDF文件的某些页面。以以下字符串类型存储的书页：String pages = "1,2,3,6,9"; 我想将此字符串作为方法的参数看起来像：pages(1,2,3,6,9); java大神给出的解决方案 使用流可以很容易地做到这一点：St…
java.net.URI.create异常 - javajava.net.URI.create("http://adserver.adtech.de/adlink|3.0") 抛出java.net.URISyntaxException: Illegal character in path at index 32: http://adserver.adtech.de/adlink|3.0 虽然n…
AppCompat不支持当前主题 - java我的应用在Android N上运行正常，但在Android M上的setContentView(R.layout.activity_main)崩溃： Caused by: java.lang.IllegalArgumentException: AppCompat does not support the current theme features: { w…
如何在Java中以语言环境正确的顺序格式化日期和月份？ - java有没有一种方法可以用Java / Kotlin中的区域设置正确的格式格式化日和月（以紧凑格式）而不格式化年份？因此，对于英语，应为“ 9月20日”，而对于瑞典语为“ 9月20日”。为了进行比较，在Cocoa平台上，我可以执行以下操作（在Swift中）：let formatter = DateFormatter() formatter.locale = Loc…