Method copyAndClose

app/src/main/java/androidx/room/CursorUtil.java:47–81

Copies the given cursor into a in-memory cursor and then closes it. This is useful for iterating over a cursor multiple times without the cost of JNI while reading or IO while filling the window at the expense of memory consumption. @param c the cursor to copy. @return a new cursor containing t

(@NonNull Cursor c)

     * @return a new cursor containing the same data as the given cursor.
     */
    @NonNull
    public static Cursor copyAndClose(@NonNull Cursor c) {
        final MatrixCursor matrixCursor;
        try {
            matrixCursor = new MatrixCursor(c.getColumnNames(), c.getCount());
            while (c.moveToNext()) {
                final Object[] row = new Object[c.getColumnCount()];
                for (int i = 0; i < c.getColumnCount(); i++) {
                    switch (c.getType(i)) {
                        case Cursor.FIELD_TYPE_NULL:
                            row[i] = null;
                            break;
                        case Cursor.FIELD_TYPE_INTEGER:
                            row[i] = c.getLong(i);
                            break;
                        case Cursor.FIELD_TYPE_FLOAT:
                            row[i] = c.getDouble(i);
                            break;
                        case Cursor.FIELD_TYPE_STRING:
                            row[i] = c.getString(i);
                            break;
                        case Cursor.FIELD_TYPE_BLOB:
                            row[i] = c.getBlob(i);
                            break;
                        default:
                            throw new IllegalStateException();
                    }
                }
                matrixCursor.addRow(row);
            }
        } finally {
            c.close();
        }
        return matrixCursor;
    }

    /**
     * Patches {@link Cursor#getColumnIndex(String)} to work around issues on older devices.