void setField(int fieldno, byte[] s, double value);

Function setField() puts values to a field in memory before writing a record to a disc.
There are different versions of setField: you can pass a double value, a string or both. In last case setField will use a value which is more suitable for this type of field.

If your string contains non-ASCII characters, you have to pass one more parameter EncodingInfo.

    // your code
    dbf.setField(0, "string value");
    dbf.setField(1, 123.45);
    dbf.setField(2, "the string", 666.66);
    dbf.setField(0, "string value", e);
    dbf.setField(2, "the string", 666.66, e);
    // your code