Add selectedItemPropertyFor(ComboBox)

HMCLCore/src/main/java/org/jackhuang/hmcl/util/SelectionModelSelectedItemProperty.java

@@ -0,0 +1,42 @@
+/*
+ * Hello Minecraft! Launcher.
+ * Copyright (C) 2018  huangyuhui <huanghongxun2008@126.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see {http://www.gnu.org/licenses/}.
+ */
+package org.jackhuang.hmcl.util;
+
+import javafx.beans.property.SimpleObjectProperty;
+import javafx.scene.control.ComboBox;
+import javafx.scene.control.SelectionModel;
+
+public class SelectionModelSelectedItemProperty<T> extends SimpleObjectProperty<T> {
+
+    public static <T> SelectionModelSelectedItemProperty<T> selectedItemPropertyFor(ComboBox<T> comboBox) {
+        return new SelectionModelSelectedItemProperty<>(comboBox.getSelectionModel());
+    }
+
+    private SelectionModel<T> model;
+
+    public SelectionModelSelectedItemProperty(SelectionModel<T> model) {
+        this.model = model;
+        model.selectedItemProperty().addListener((observable, oldValue, newValue) -> set(newValue));
+        set(model.getSelectedItem());
+    }
+
+    @Override
+    protected void invalidated() {
+        model.select(get());
+    }
+}