解析XML并在getter中创建防御性副本 - Java JABX

Question

我正在尝试使用java JABX解析XML文件并创建一组对象。我有一个类，我想将xml映射到：

$('ul').mousewheel(function(event, delta) {
  this.scrollLeft -= (delta * 20);
  event.preventDefault();   
});

如果在getter方法中我有public class Dash implements Serializable { private List<ViewBlock> viewBlocks = new ArrayList<ViewBlock>(); public List<ViewBlock> getViewBlocks() { return viewBlocks; // ---> this works //return new ArrayList<ViewBlock>(viewBlocks); ---> this doesn't } public void setViewBlocks(List<ViewBlock> viewBlocks) { this.viewBlocks.clear(); this.viewBlocks.addAll(viewBlocks); } } 它可以正常工作但是当我使用第二个选项return viewBlocks时，我的数组列表为空。我需要它来返回数组的副本并解析xml，这可能吗？

Answer 1

尝试通过添加空检查进行更改，并确保进行初始化。

 public class Dash implements Serializable {

    private List<ViewBlock> viewBlocks = new ArrayList<ViewBlock>();

    public List<ViewBlock> getViewBlocks() {

      if (viewBlocks== null) {
            numbers = new ArrayList<ViewBlock>();
        }          
        return viewBlocks;
    }
    public void setViewBlocks(List<ViewBlock> viewBlocks) {
        this.viewBlocks.clear();
        this.viewBlocks.addAll(viewBlocks);
    }
}