Convert List<Map<String, Object>> to String[][]

Question

I have a List<Map<String, Object>> data.

public List<Map<String, Object>> selectAll(String tableName) throws SQLException{
    MapListHandler mapListHandler = new MapListHandler();
    QueryRunner queryRunner = new QueryRunner();
    List<Map<String, Object>> list = queryRunner.query(DBConnection.getConnection(), SELECT + tableName, mapListHandler);
    System.out.println(list);
    return list;
}

Then I get this

List<Map<String, Object>> data = databaseMetadata.selectAll(buttonElements.getTables_in_migrate_schema());

And I need to add it to JTable as rowData so it has to be String[][].

I tried to make something like this.

JTable jTable = new JTable((Object[][]) data.toArray(), fields.toArray());

Can someone please say me how to convert? Thanks in advance!

List<Map> is 3D. String[][] is 2D. Can you show us what have you tried(code)? — KunLun
– KunLun, Commented Sep 14, 2020 at 12:51
What part of data do you want to see in e.g. column 5 of row 2? It's not at all obvious how you want that structure mapped to a JTable. — Ralf Kleberhoff
– Ralf Kleberhoff, Commented Sep 14, 2020 at 13:00

Eklavya · Accepted Answer · 2020-09-14 13:40:09Z

1

As you already have the field's name, so just collect every map's value of list and collect as 2D Object array. You can use Stream API this way

Object[][] objList = data.stream().map(m -> m.values().toArray()).toArray(Object[][]::new);

answered Sep 14, 2020 at 13:40

Eklavya

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