收藏时会判断失误，然后出现重复收藏的情况

首次点击收藏时运行良好，再次点击时也能判断出已收藏。但是在上下页翻动后，判断是否收藏的机制出现异常。之后任意一篇点击收藏后再次点击收藏也能再次收藏，甚至是同篇的多次收藏。

MainActivity.java
package com.example.self_application_homework.activity;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;相关截图：
import android.widget.TextView;
import android.widget.Toast;

import com.example.self_application_homework.R;
import com.example.self_application_homework.bean.Article;
import com.example.self_application_homework.biz.ArticleBiz;
import com.example.self_application_homework.dao.ArticleDao;
import com.example.self_application_homework.dao.ArticleDbHelper;
import com.example.self_application_homework.utils.ImageLoader;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private Button mBtnDeleteDb;

    private Button mBtnLastOne, mBtnCollect, mBtnNextOne;
    private TextView mTvMyfavourites, mTvTitle, mTvAuthor, mTvContent;
    private ImageView mIvAdvertise;

    // for advertisement bitmap
    private ImageLoader imageLoader;

    // for current page article
    int currentPage = 1;
    private ArticleBiz mArticleBiz = new ArticleBiz();
    private ArticleDao mArticleDao = new ArticleDao();
    private Article article = new Article();

    // for MyFavourites
    Intent itToMyFavourites = null;
    List<Article> articleList = new ArrayList<>();

    private static final String TAG = "MainActivity -app";

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

        initViewsNDatas();

        loadAdvertisement();

        loadDatas(currentPage, false);
    }

    private void initViewsNDatas() {
        mBtnLastOne = findViewById(R.id.id_btn_lastOne);
        mBtnCollect = findViewById(R.id.id_btn_collect);
        mBtnNextOne = findViewById(R.id.id_btn_nextOne);
        mTvMyfavourites = findViewById(R.id.id_tv_myFavourites);
        mTvTitle = findViewById(R.id.id_tv_title);
        mTvAuthor = findViewById(R.id.id_tv_author);
        mTvContent = findViewById(R.id.id_tv_content);
        mIvAdvertise = findViewById(R.id.id_iv_advertise);

        itToMyFavourites = new Intent(MainActivity.this, MyFavouritesActivity.class);

        mBtnDeleteDb = findViewById(R.id.id_btn_deleteDb);
    }

    public void initEvenets(View v) {
        switch (v.getId()) {
            case R.id.id_tv_myFavourites:
                // 打开收藏页面
                if (mArticleDao.loadFromDb(this).isEmpty())
                    Toast.makeText(this, "还没收藏任何内容", Toast.LENGTH_SHORT).show();
                else
                    startActivity(itToMyFavourites);
                break;
            case R.id.id_btn_lastOne:
                // 打开上一页
                Log.d(TAG, "currentPage: " + currentPage);
                loadDatas(loadPage(false), true);
                break;
            case R.id.id_btn_collect:
                // 点击收藏按钮
                List<Article> articleList = mArticleDao.loadFromDb(this);

                // 先判断收藏里（数据库）是否为空，为空直接添加数据，不为空则进一步判断
                if (articleList.isEmpty() || articleList == null) {
                    mArticleDao.insertToDb(this, article);
                    Toast.makeText(this, "收藏成功", Toast.LENGTH_SHORT).show();
                    Log.d(TAG, "articleList.isEmpty(): " + articleList.isEmpty());
                } else {
                    // 收藏中有相同的文章则跳过，否则添加巾数据库
                    for (Article articleInLoop : articleList) {
                        Log.d(TAG, "article.getTitle().equals(articleInLoop.getTitle()): " + article.getTitle().equals(articleInLoop.getTitle()));
                        if (article.getTitle().equals(articleInLoop.getTitle())) {
                            Toast.makeText(this, "此文章已收藏", Toast.LENGTH_SHORT).show();
                        } else {
                            mArticleDao.insertToDb(this, article);
                            Toast.makeText(this, "收藏成功", Toast.LENGTH_SHORT).show();
                        }
                    }
                }
                break;
            case R.id.id_btn_nextOne:
                // 打开下一页
                loadDatas(loadPage(true), true);
                break;
            case R.id.id_btn_deleteDb:
                // 删库
                mArticleDao.deleteDb(this);
                Toast.makeText(this, "数据库已清空", Toast.LENGTH_SHORT).show();
                break;
        }
    }

    private void loadAdvertisement() {
        imageLoader = new ImageLoader();
        int random = (int) (3 * Math.random() + 1);
        imageLoader.loadImageByAsynTask(mIvAdvertise, "http://www.imooc.com/api/teacher?type=1", random);
    }

    private void loadDatas(int page, boolean isUseCache) {
        mArticleBiz.loadDatas(new ArticleBiz.Callback() {
            @Override
            public void onSuccess(Article resultArticle) {
                article = resultArticle;
                mTvTitle.setText(article.getTitle());
                mTvAuthor.setText(article.getAuthor());
                mTvContent.setText(article.getContent());
            }

            @Override
            public void onFailure(Exception ex) {
                ex.printStackTrace();
            }
        }, page, isUseCache);
    }

    private int loadPage(boolean nextPage) {
        if (nextPage == true)
            currentPage++;
        else
            currentPage--;

        if (currentPage < 1)
            currentPage = 30;
        if (currentPage > 30)
            currentPage = 1;

        return currentPage;
    }

}

​ArticleDao.java
​package com.example.self_application_homework.dao;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

import androidx.annotation.NonNull;

import com.example.self_application_homework.bean.Article;

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

public class ArticleDao {
    public List<Article> loadFromDb(@NonNull Context context) {

        ArticleDbHelper dbHelper = ArticleDbHelper.getInstance(context);
        SQLiteDatabase db = dbHelper.getWritableDatabase();

        List<Article> articleList = new ArrayList<>();

        Cursor cursor = db.rawQuery("SELECT * FROM " + Article.TABLE_NAME, null);
        Article article = null;
        while (cursor.moveToNext()) {
            int id = cursor.getInt(cursor.getColumnIndex(Article.COL_ID));
            String title = cursor.getString(cursor.getColumnIndex(Article.COL_TITLE));
            String author = cursor.getString(cursor.getColumnIndex(Article.COL_AUTHOR));
            String content = cursor.getString(cursor.getColumnIndex(Article.COL_CONTENT));
            article = new Article(title, author, content);
            articleList.add(article);
        }
        cursor.close();

        return articleList;
    }

    public void insertToDb(@NonNull Context context, Article article) {

        if (article == null) {
            return;
        }

        ArticleDbHelper dbHelper = ArticleDbHelper.getInstance(context);
        SQLiteDatabase db = dbHelper.getWritableDatabase();

        db.beginTransaction();

        ContentValues contentValues = null;
        contentValues = new ContentValues();
        contentValues.put(Article.COL_TITLE, article.getTitle());
        contentValues.put(Article.COL_AUTHOR, article.getContent());
        contentValues.put(Article.COL_CONTENT, article.getAuthor());
        db.insertWithOnConflict(Article.TABLE_NAME, null, contentValues, SQLiteDatabase.CONFLICT_REPLACE);

        db.setTransactionSuccessful();
        db.endTransaction();
    }

    public void deleteDb(@NonNull Context context) {
        ArticleDbHelper dbHelper = ArticleDbHelper.getInstance(context);
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        db.execSQL("DELETE FROM " + Article.TABLE_NAME);
    }
}