使用 JList 显示 TreeMap 对象
我想遍历 TreeMap 将对象添加到 DefaultListModel，然后添加到 JList。但是，列表中仅显示键值，而不显示对象。我该如何纠正这个问题？
请参见下面的代码：
public class ViewInventoryInterface extends JFrame {
private Inventory theInventory; // reference to back end
private InventoryUPCIterator iter;
private DefaultListModel dlm;
private JList list;
private JScrollPane scroll;
public ViewInventoryInterface(Inventory theInventory) {
this.theInventory = theInventory;
iter = theInventory.inventoryUPCIterator(); //returns an iterator for the inventory
dlm = new DefaultListModel();
while (iter.hasNext()) {
dlm.addElement(iter.next());
}
list = new JList(dlm);
scroll = new JScrollPane(list);
setTitle("Inventory");
add(scroll);
setSize(400, 400);
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
}
}
这是创建迭代器的类
public class InventoryUPCIterator {
private Set<String> keys;
private Iterator<String> iter;
public InventoryUPCIterator(HashMap<String, ItemIndex> inventory) {
TreeMap<String, ItemIndex> values = new TreeMap<String, ItemIndex>(
inventory);
// sorts the index according to the natural ordering of String values
keys = values.keySet();// returns set of sorted keys
iter = keys.iterator();
}
public boolean hasNext() {
return iter.hasNext();
}
public String next() {
return iter.next();
}
public void reset() {
iter = keys.iterator();// start again from the beginning
}
}
I would like to iterate through a TreeMap to add objects to a DefaultListModel and then to a JList. However, only the key values are displayed in the list and not the object. How can I correct this?
see code below:
public class ViewInventoryInterface extends JFrame {
private Inventory theInventory; // reference to back end
private InventoryUPCIterator iter;
private DefaultListModel dlm;
private JList list;
private JScrollPane scroll;
public ViewInventoryInterface(Inventory theInventory) {
this.theInventory = theInventory;
iter = theInventory.inventoryUPCIterator(); //returns an iterator for the inventory
dlm = new DefaultListModel();
while (iter.hasNext()) {
dlm.addElement(iter.next());
}
list = new JList(dlm);
scroll = new JScrollPane(list);
setTitle("Inventory");
add(scroll);
setSize(400, 400);
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
}
}
and this is the class from which the iterator is created
public class InventoryUPCIterator {
private Set<String> keys;
private Iterator<String> iter;
public InventoryUPCIterator(HashMap<String, ItemIndex> inventory) {
TreeMap<String, ItemIndex> values = new TreeMap<String, ItemIndex>(
inventory);
// sorts the index according to the natural ordering of String values
keys = values.keySet();// returns set of sorted keys
iter = keys.iterator();
}
public boolean hasNext() {
return iter.hasNext();
}
public String next() {
return iter.next();
}
public void reset() {
iter = keys.iterator();// start again from the beginning
}
}
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评论（2）
您仅将键值添加到 dlm 对象中，
修改上面的循环以添加该值
You are only adding the key value into the dlm object
modify the above loop to add the value as well
不幸的是，您没有展示如何获取迭代器（
theInventory.inventoryUPCIterator()）。但我相信您写了类似 map.entries().iterator() 的东西，它返回条目的迭代器（即键值对）。使用 map.keySet() 或 key.values() 代替，或者在迭代条目时使用entry.getKey()。Unfortunately you have not showed how do you get the iterator (
theInventory.inventoryUPCIterator()). But I believe that you wrote something like map.entries().iterator() that returns iterator of entries (i.e. key-value pairs). Use map.keySet() or key.values() instead or useentry.getKey()when iterating entries.