Java - ArrayList - Get a value from an Array of array

Question

I save some values from database using this function (i've been replaced Vector, because is deprecated) :

// database function
public ArrayList<String[]> selectQuery(String query) {
    ArrayList<String[]> v = null;
    String [] record;
    int colonne = 0;
    try {
        Statement stmt = db.createStatement();
        ResultSet rs = stmt.executeQuery(query);
        v = new ArrayList<String[]>();
        ResultSetMetaData rsmd = rs.getMetaData();
        colonne = rsmd.getColumnCount();

        while(rs.next()) {
            record=new String[colonne];
            for (int i=0; i<colonne; i++) record[i] = rs.getString(i+1);
            v.add((String[])record);
        }
        rs.close();
        stmt.close();
    } catch (Exception e) { e.printStackTrace(); errore = e.getMessage(); }

    return v;
}

// here i print the result, after call that function
ArrayList db_result=null;
db_result=mydb.selectQuery("SELECT titolo, user, date FROM articles WHERE category='1' ORDER by ID ASC");

int i=0;
while (i<db_result.size() ) {
    affitta_3.createLabel().setLabel(db_result.get(i)[0]);
    affitta_3.createLabel().setLabel(db_result.get(i)[1]);
    affitta_3.createLabel().setLabel(db_result.get(i)[2]);
    affitta_3.createLabel().setLabel(db_result.get(i)[3]);
   i++;
}

So, i save many String-array in an array. Now, how can I get (for example) the 4° value from the 2° Array String?

"...arrays and generics do not mix well." -- Joshua Bloch, Effective Java Second Edition, p. 119. Also implicit in this is arrays and collections not mixing well, due to generics. — Powerlord
– Powerlord, Commented Nov 16, 2010 at 21:26

Jon Skeet · Accepted Answer · 2010-11-16 21:03:46Z

1

Why are you bothering to clone the string array when nothing else will have a reference to it?

Anyway, you'd get at the string using:

String value = v.get(1)[3];

(assuming that v is of type List<String[]> or something similar).

answered Nov 16, 2010 at 21:03

Jon Skeet

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3 Comments

markzzz Over a year ago

uhm. if i have record=(String) db_result.get(0)[0]; it doesnt work (String [] record)

markzzz Over a year ago

take a look at the updated topic. Maybe is clear :) if i do it it says "array required, by java.lang.Object found"

markzzz Over a year ago

ok solved. :) db_result.get(i)[0] and ArrayList<String[]> db_result=null; thanks you help me :)

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