using JSONGenerator with Apex/SFDC

jsongenerator_sample.cls

Hoge p = new Hoge();
p.code = '0001';
p.name = 'hogename1';
p.items = new List<HogeItem>{
    new HogeItem('0001-01', 'item001'),
    new HogeItem('0001-02', 'item002')
};

JSONGenerator jg = JSON.createGenerator(false);
jg.writeObject(p);
System.debug(jg.getAsString());

public class Hoge {
    public String code;
    public String name;
    public List<HogeItem> items;
}
public class HogeItem {
    public String itemcode;
    public String itemname;
    public HogeItem(String code, String name) {
        this.itemcode = code;
        this.itemname = name;
    }
}