Here you can find the source of contains(final JComboBox
public static boolean contains(final JComboBox<String> comboBox, final Object item)
//package com.java2s; /*// w w w. jav a 2 s . c o m * Copyright (C) 2014 by Array Systems Computing Inc. http://www.array.ca * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the Free * Software Foundation; either version 3 of the License, or (at your option) * any later version. * This program is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for * more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, see http://www.gnu.org/licenses/ */ import javax.swing.*; import java.util.HashSet; import java.util.Set; public class Main { public static boolean contains(final JComboBox<String> comboBox, final Object item) { final Set<Object> items = new HashSet<>(); for (int i = 0; i < comboBox.getItemCount(); i++) { items.add(comboBox.getItemAt(i)); } return items.contains(item); } }