how to add values to dropdown list in java jframe code example

Example: combobox swing

String[] petStrings = { "Bird", "Cat", "Dog", "Rabbit", "Pig" };

//Create the combo box, select item at index 4.
//Indices start at 0, so 4 specifies the pig.
JComboBox petList = new JComboBox(petStrings);
petList.setSelectedIndex(4);
petList.addActionListener(this);