我有SQLite数据库，我在那里保存数据，我想为每个新的条目检查数据库，如果已经存在这个记录，如果是，给我一个吐司词，如果没有插入数据库中的记录。我想检查搜索URL和本地URL是否存在于数据库中。
下面是代码。

public class BookmarkDB extends SQLiteOpenHelper {
    public static final String DBNAME = "bookmarks.db"; // The name of the database file
    public static final int DBVERSION = 1;  // The Database version

    public static final String TBL_BOOKMARK = "bookmark";
    public static final String COL_ID = BaseColumns._ID; // equates to _id
    public static final String COl_NAME = "name";
    public static final String COl_HIDDEN = "hidden";
    public static final String COL_ICON = "icon";
    public static final String COL_NATIVEURL = "nativeurl";
    public static final String COL_SEARCHURL = "searchurl";

    SQLiteDatabase mDB;
    Context mContext;

    public BookmarkDB(Context context) {
        super(context, DBNAME, null, DBVERSION);
        mDB = this.getWritableDatabase();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

        // The SQL to be used to create the table
        String crt_bookmark_tbl_sql = "CREATE TABLE IF NOT EXISTS " + TBL_BOOKMARK + "(" +
                COL_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                COl_NAME + " TEXT, " +
                COl_HIDDEN + " INTEGER, " +
                COL_ICON + " TEXT, " +
                COL_NATIVEURL + " TEXT," +
                COL_SEARCHURL + " TEXT" +
                ")";
        db.execSQL(crt_bookmark_tbl_sql); // CREATE THE TABLE

    }

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

    public long addBookmark(long id, String name, boolean hidden, String icon, String nativeurl, String searchurl) {
        ContentValues cv = new ContentValues();

                    cv.put(COl_HIDDEN,hidden);
                    cv.put(COl_NAME,name);
                    cv.put(COL_ICON,icon);
                    cv.put(COL_NATIVEURL,nativeurl);
                    cv.put(COL_SEARCHURL,searchurl);
                  return  mDB.insert(TBL_BOOKMARK, null, cv);

        // uses the convenience insert method that builds the SQL
    }
    public ArrayList<Bookmark> getAllBookmarks() {
        ArrayList<Bookmark> rv  = new ArrayList<>();
        Cursor csr = mDB.query(TBL_BOOKMARK,null,null,null,null,null, null);

        while (csr.moveToNext()) {
            Bookmark b = new Bookmark();
            b.setId(csr.getString(csr.getColumnIndex(COL_ID)));
            int Icon = csr.getInt(csr.getColumnIndex(COL_ICON));
            String name = csr.getString(csr.getColumnIndex(COl_NAME));
            String searchUrl = csr.getString(csr.getColumnIndex(COL_SEARCHURL));
            b.setIcon(Icon);
            b.setName(name);
            b.setSearchUrl(searchUrl);
            b.setViewType(csr.getInt(csr.getColumnIndex(COl_NAME)));
            b.setNativeUrl(csr.getString(csr.getColumnIndex(COL_NATIVEURL)));
            rv.add(b);
        }
        return rv;

    }

    public void deleteBookmark(int id, String name){
        SQLiteDatabase db = this.getWritableDatabase();
        String query = "DELETE FROM " + TBL_BOOKMARK + " WHERE "
                + COL_ID + " = '" + id + "'" +
                " AND " + COl_NAME + " = '" + name + "'";

        Log.d("Deleted", "Item" + query);
        db.execSQL(query);
    }

}

保存新记录的代码

public class ActivityChangeBookmark  extends AppCompatActivity {
    private ArrayList<String> listItems = new ArrayList<String>();
    private RecyclerView recyclerView;
    Button saveBookmark, cancelBookmark;
    TextView name, url;
    ImageView icon, mIcon;
    EditText mName, mUrl, mID;
    public static final String Save_Bookmark = "Save_Bookmark";
    static final String xmlFileName = "bookmarks.xml";
    String Url, Name;
    Integer Id;
    MyAdapter myAdapter;
     BookmarkDB bookmarkDB;
     ButtonRobotoMedium removeBookmark, sendToHomeScreen;
    ArrayList<Bookmark> arrayList = new ArrayList<>();

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_change_bookmark);
        saveBookmark = findViewById(R.id.btnSave);
        name = findViewById(R.id.tvNameEdit);
        url = findViewById(R.id.tvURLEdit);
        recyclerView = findViewById(R.id.myRecyclerView);
        icon = findViewById(R.id.ivFavIcon);
        mName = findViewById(R.id.etNameEdit);
        mUrl = findViewById(R.id.etURLEdit);
        cancelBookmark = findViewById(R.id.btnCancel);
        removeBookmark = findViewById(R.id.btnRemove);
        sendToHomeScreen = findViewById(R.id.btnAddIconToDeviceScreen);
        name.setVisibility(View.GONE);
        url.setVisibility(View.GONE);
        bookmarkDB = new BookmarkDB(getApplicationContext());
        Intent intent = getIntent();
        myAdapter = new MyAdapter(getApplicationContext(), arrayList);

        Bundle extras = intent.getExtras();
        if (extras != null) {
            Url = intent.getExtras().getString("Url");
            Name = intent.getExtras().getString("Name");
            Id = intent.getExtras().getInt("ID");

            Bitmap bitmap = intent.getExtras().getParcelable("Image");
            mName.setText(Name);
            mUrl.setText(Url);
            Log.d("Id", "TakenId" + Id + Name + Url);

            icon.setImageBitmap(bitmap);
            removeBookmark.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Log.d("DeletedItem", "Test" + Id + Name);
                    bookmarkDB.deleteBookmark(Id, Name);
                    myAdapter.notifyDataSetChanged();
                    finish();
                }
            });
        }
         else {
            removeBookmark.setVisibility(View.GONE);
            sendToHomeScreen.setVisibility(View.GONE);
            icon.setImageResource(R.drawable.user_bookmark);
            mName.setText("");
            mUrl.setText("");
        }


        saveBookmark.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                saveData();
                myAdapter.notifyDataSetChanged();
                finish();
                }
        });

        cancelBookmark.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                myAdapter.notifyDataSetChanged();
                finish();
            }
        });
    }

    public void saveData() {
        Random r = new Random();
        int low = 14;
        int high = 100;
        int result = r.nextInt(high-low) + low;
        bookmarkDB.addBookmark(result, mName.getText().toString(), false, "", mUrl.getText().toString(), "http://" + mUrl.getText().toString());
    }
}