这是有关订购对象的教程：

Java教程-集合-对象排序
尽管我会举一些例子，但我还是建议你阅读它。

有多种排序方式ArrayList。如果要定义自然的（默认）排序，则需要让ContactImplement实现Comparable。假设你想默认在上进行排序name，然后执行（为简单起见，省略了nullchecks）：

public class Contact implements Comparable<Contact> {

    private String name;
    private String phone;
    private Address address;

    public int compareTo(Contact other) {
        return name.compareTo(other.name);
    }

    // Add/generate getters/setters and other boilerplate.
}

这样你就可以做

List<Contact> contacts = new ArrayList<Contact>();
// Fill it.

Collections.sort(contacts);

如果要定义外部可控排序（覆盖自然排序），则需要创建一个Comparator：

List<Contact> contacts = new ArrayList<Contact>();
// Fill it.

// Now sort by address instead of name (default).
Collections.sort(contacts, new Comparator<Contact>() {
    public int compare(Contact one, Contact other) {
        return one.getAddress().compareTo(other.getAddress());
    }
}); 

你甚至可以Comparator在Contact自身中定义，以便你可以重用它们，而不必每次都重新创建它们：

public class Contact {

    private String name;
    private String phone;
    private Address address;

    // ...

    public static Comparator<Contact> COMPARE_BY_PHONE = new Comparator<Contact>() {
        public int compare(Contact one, Contact other) {
            return one.phone.compareTo(other.phone);
        }
    };

    public static Comparator<Contact> COMPARE_BY_ADDRESS = new Comparator<Contact>() {
        public int compare(Contact one, Contact other) {
            return one.address.compareTo(other.address);
        }
    };

}

可以如下使用：

List<Contact> contacts = new ArrayList<Contact>();
// Fill it.

// Sort by address.
Collections.sort(contacts, Contact.COMPARE_BY_ADDRESS);

// Sort later by phone.
Collections.sort(contacts, Contact.COMPARE_BY_PHONE);

为了使结果更好，你可以考虑使用通用的javabean比较器：

public class BeanComparator implements Comparator<Object> {

    private String getter;

    public BeanComparator(String field) {
        this.getter = "get" + field.substring(0, 1).toUpperCase() + field.substring(1);
    }

    public int compare(Object o1, Object o2) {
        try {
            if (o1 != null && o2 != null) {
                o1 = o1.getClass().getMethod(getter, new Class[0]).invoke(o1, new Object[0]);
                o2 = o2.getClass().getMethod(getter, new Class[0]).invoke(o2, new Object[0]);
            }
        } catch (Exception e) {
            // If this exception occurs, then it is usually a fault of the developer.
            throw new RuntimeException("Cannot compare " + o1 + " with " + o2 + " on " + getter, e);
        }

        return (o1 == null) ? -1 : ((o2 == null) ? 1 : ((Comparable<Object>) o1).compareTo(o2));
    }

}

你可以使用以下方法：

// Sort on "phone" field of the Contact bean.
Collections.sort(contacts, new BeanComparator("phone"));

（如你在代码中所见，可能的空字段已经被覆盖以避免在排序过程中出现NPE）