JavaFX：将TextArea绑定到所选TreeItem的元素（包含在TreeView中） [英] JavaFX: Binding TextArea to element of selected TreeItem (contained in TreeView)

问题描述

我正在构建以下JavAFX，而且我对它完全不熟悉。以下是它的样子：

I'm building the following JavAFX and I'm pretty new to it altogether. Here's what it looks like:

http：// i.imgur.com/nfzQzIY.png

正如你所看到的那样，有一个 TreeView 左边以及中心的一些 TextArea 。请忽略其余部分。

As you can see there's a TreeView on the left as well as some TextAreas in the centre. Please ignore the rest.

左边的字母数字字符串 TreeView 是 PlugTreeItem 类对象，我为扩展TreeItem而构建，并为 Plug 项目添加了一个额外的持有者，如下所示：

The alphanumeric Strings on the left TreeView are PlugTreeItem class objects, which I've built to extend TreeItem and have an additional holder for a Plug item, like so:

public class PlugTreeItem<T> extends TreeItem{

    private Plug plugItem = null;

    //########################### PROCS ########################################

    public PlugTreeItem(Object t, Plug pl) {
        super(t);
        plugItem = pl;
    }

    public PlugTreeItem(Object t, Node node, Plug pl) {
        super(t, node);
        plugItem = pl;
    }

    public void setPlugItem(Plug plugItem) {
        this.plugItem = plugItem;
    }

    public Plug getPlugItem() {
        return plugItem;
    }
}

TreeView 是通过从SQL DB读取 Plug 来构建的，创建 PlugTreeItem 对象，将插件链接到 PlugTreeItem 然后将其添加到树的根节点（最初创建为虚拟），我们从中创建 TreeView ：
注意： result_set包含SQL结果矩阵。 MAC是包含您在屏幕截图左侧看到的地址的字段。

And the TreeView is built by reading Plugs off an SQL DB, creating PlugTreeItem objects, linking the plug to the PlugTreeItem then adding that to the tree's root node (which was created initially, as a dummy), out of which we make the TreeView: NOTE: result_set contains the SQL result matrix. MAC is the field that contains the addresses you see in left of the screenshot.

treeItemRoot = new PlugTreeItem<>("Active Plugs", new Plug());          //Root of the tree, contains a dummy Plug object.
selectedTreeItem = treeItemRoot;  //Holder of our currently selected TreeItem, see Listener below.

TreeView<String> treeView = new TreeView<>(treeItemRoot);

while(result_set.next()){
    Plug pl = null;                                         
    pl = new Plug(result_set.getString("SIHUid"), result_set.getString("sensorID"), result_set.getString("Location"), result_set.getString("Appliance"), result_set.getString("Type"), result_set.getString("connection"));
    PlugTreeItem<String> pti = new PlugTreeItem(pl.getMAC(),pl);
    treeItemRoot.getChildren().add(pti);
}

最后，我有一些TextAreas，正如你在截图中看到的那样应用程序。我希望那些在 TreeView 中反映所选 PlugTreeItem 的元素，让我们从Plug MAC TextArea开始我想反映你在左边看到的相同值。

Finally, I've got some TextAreas as you see in the screenshot of the app. I want those to reflect the elements of the selected PlugTreeItem in the TreeView, let's just start with the Plug MAC TextArea that I want to reflect the same value that you see on the left.

我已将以下监听器添加到 selectedTreeItem 这样每次用户点击 TreeItem 时， selectedTreeItem 都会更新并保留对该特定<的引用 PlugTreeItem ：

I've added the following listener to selectedTreeItem so that every time the user clicks on a TreeItem, the selectedTreeItem gets updated and holds a reference to that specific PlugTreeItem:

treeView.getSelectionModel().selectedItemProperty().addListener( new ChangeListener() {     
            @Override
            public void changed(ObservableValue observable, Object oldValue, Object newValue) { 
                selectedTreeItem = (PlugTreeItem<String>) newValue;
                System.out.println("Selection plug MAC: " + selectedTreeItem.getPlugItem().getMAC());           //MARKER: REMOVE
                // do what ever you want 
            }
        });

希望这符合我的想法。 System.out 命令确认每当我点击树上的不同项目时，我点击的MAC地址就会被打印出来。

Hopefully this does what I think it is. The System.out command confirms that whenever I click on different items on the tree, the MAC address that I clicked on gets printed.

我怎样才能告诉我的TextAreas嘿，听看selectedTreeItem。每当它改变时，得到一个特定值并将其设置为你的文字？

How can I tell my TextAreas to "hey, listen to selectedTreeItem. Whenever it changes, get a specific value and set it as your text"?

我已经尝试在 Plug 的特定字段上添加第二个Listener，我已经从String更改为 StringProperty 所以它变成 ObservableValue 。但是，即使将TextArea的textProperty与StringProperty绑定在一起之后，它也不会更改其内容。

I've tried adding a second Listener on a specific field of Plug that I've changed from String to StringProperty so that it becomes an ObservableValue. However, even after binding the TextArea's textProperty with the StringProperty, it doesn't change its contents.

我知道我可能因为其错误而错误地提出了我的问题。尺寸。如果我有任何其他信息或代码我可能已经省略或您认为不重要，请不要犹豫。

推荐答案

我不会仅为此创建TreeItem的子类。它被设计用于任何对象。对于TextArea绑定，只需在选择更改的侦听器中绑定和取消绑定。

I would not make a subclass of TreeItem just for that. It's designed to be used with any object. For the TextArea bindings, just bind and unbind in the selection changed listener.

package treebind;

import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.Scene;
import javafx.scene.control.TextArea;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class TreeBind extends Application {

    @Override
    public void start(Stage primaryStage) {

        TreeItem<Plug> treeItemRoot = new TreeItem<>(new Plug("root","a"));
        TreeView<Plug> treeView = new TreeView<>(treeItemRoot);
        for (int i=0;i<10;i++)
            treeItemRoot.getChildren().add(new TreeItem<>(new Plug("name"+String.valueOf(i),"")));
        treeView.setMinWidth(150);

        final TextArea ta1 = new TextArea();

        treeView.getSelectionModel().selectedItemProperty().addListener(new ChangeListener() {
            @Override
            public void changed(ObservableValue observable, Object oldValue, Object newValue) {
                if (oldValue!=null){
                    ((TreeItem<Plug>)oldValue).getValue().s1.unbindBidirectional(ta1.textProperty());
                    ta1.clear();
                }
                if (newValue!=null){
                    ta1.setText(((TreeItem<Plug>)newValue).getValue().s1.getValue());
                    ((TreeItem<Plug>)newValue).getValue().s1.bindBidirectional(ta1.textProperty());
                }
            }
        });

        HBox root = new HBox();
        root.getChildren().addAll(treeView,ta1);
        Scene scene = new Scene(root, 400, 300);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private class Plug{
        public final StringProperty name, s1;

        Plug(String name, String s1){
            this.name = new SimpleStringProperty(name);
            this.s1 = new SimpleStringProperty(s1);
        }
        @Override
        public String toString(){
            return name.getValue();
        }
    }
}

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