Change background for new or changed records-优快云博客

本文介绍了一种使用TableViewer在Eclipse RCP中为新记录或已更改记录设置背景颜色的方法。通过重写hashCode方法来标识对象状态的变化，并利用HashMap存储已保存记录的状态。在显示时，根据记录是否为新记录或已修改来改变其背景颜色。

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TableViewer: Change background for new or changed records

1) //override hashCode() of the class that displayed in the table.

/**
 * Calculate these fields that affect the object state to change
 */
public int hashCode() {
    return BaseUtils.hashCode(id, name, sex, date, value);
}

2) In UI

//<PrimaryKey, hashCode>
private Map<Object, Integer> states = new HashMap<Object, Integer>();

3) //Init or Save


//After persistenting, the Person.getID() is not null.
for (Person person : persons) {
    if (person.getId() != null)
        states.put(person.getId(), person.hashCode());
}

4) get changed objects

/** Before persistenting, get changed objects */
List<Person> getChangedObjects(List<Person> list, Map<Object,Integer> states) {
    List<Person> changes = new ArrayList<Person>();
    for (Person p : list) {
        Integer hashCode = states.get(p.getId());
        if (p.getId() == null || hashCode == null || hashCode != p.hashCode()) {
            changes.add(p);
        }
    }
    return changes;
}

5)//class Provider implements ITableColorProvider


public Color getBackground(Object element, int columnIndex) {
    Person p = (Person) element;
    boolean isNew = p.getId() == null;
    boolean modified = states.containsKey(p.getId()) && states.get(p.getId()) != element.hashCode();

    if (isNew || modified)
        return RcpUI.COLOR_YELLOW;
    else
        return null;
}

public Color getForeground(Object element, int columnIndex) {
    return null;
}