Method readForeignKeys

app/src/main/java/androidx/room/TableInfo.java:175–216

(SupportSQLiteDatabase database,
            String tableName)

    }

    private static Set<ForeignKey> readForeignKeys(SupportSQLiteDatabase database,
            String tableName) {
        Set<ForeignKey> foreignKeys = new HashSet<>();
        // this seems to return everything in order but it is not documented so better be safe
        Cursor cursor = database.query("PRAGMA foreign_key_list(`" + tableName + "`)");
        try {
            final int idColumnIndex = cursor.getColumnIndex("id");
            final int seqColumnIndex = cursor.getColumnIndex("seq");
            final int tableColumnIndex = cursor.getColumnIndex("table");
            final int onDeleteColumnIndex = cursor.getColumnIndex("on_delete");
            final int onUpdateColumnIndex = cursor.getColumnIndex("on_update");

            final List<ForeignKeyWithSequence> ordered = readForeignKeyFieldMappings(cursor);
            final int count = cursor.getCount();
            for (int position = 0; position < count; position++) {
                cursor.moveToPosition(position);
                final int seq = cursor.getInt(seqColumnIndex);
                if (seq != 0) {
                    continue;
                }
                final int id = cursor.getInt(idColumnIndex);
                List<String> myColumns = new ArrayList<>();
                List<String> refColumns = new ArrayList<>();
                for (ForeignKeyWithSequence key : ordered) {
                    if (key.mId == id) {
                        myColumns.add(key.mFrom);
                        refColumns.add(key.mTo);
                    }
                }
                foreignKeys.add(new ForeignKey(
                        cursor.getString(tableColumnIndex),
                        cursor.getString(onDeleteColumnIndex),
                        cursor.getString(onUpdateColumnIndex),
                        myColumns,
                        refColumns
                ));
            }
        } finally {
            cursor.close();
        }
        return foreignKeys;
    }

    private static List<ForeignKeyWithSequence> readForeignKeyFieldMappings(Cursor cursor) {
        final int idColumnIndex = cursor.getColumnIndex("id");