GWT Listbox OnChangeHandler

Question

如何为GWT列表框显式触发OnChangeHandler？

在我的场景中，当我调用ListBox的SetSelectedIndex（X）方法时应该触发它。

Answer 1

尝试任何一个：

覆盖setSelectedIndex()方法并触发ChangeEvent

    final ListBox lb = new ListBox() {
        @Override
        public void setSelectedIndex(int index) {
            super.setSelectedIndex(index);
            DomEvent.fireNativeEvent(Document.get().createChangeEvent(), this);
        }
    };

OR

覆盖setSelectedIndex()方法并调用用于ChangeHandler同样行为的方法。

public void onModuleLoad() {

    // Make a new list box, adding a few items to it.
    final ListBox lb = new ListBox() {
        @Override
        public void setSelectedIndex(int index) {
            super.setSelectedIndex(index);
            onChangeBody(this);
        }
    };
    lb.addItem("foo");
    lb.addItem("bar");
    lb.addItem("baz");
    lb.addItem("toto");
    lb.addItem("tintin");

    lb.addChangeHandler(new ChangeHandler() {

        @Override
        public void onChange(ChangeEvent event) {
            onChangeBody(lb);
        }
    });

    // Make enough room for all five items (setting this value to 1 turns it
    // into a drop-down list).
    lb.setVisibleItemCount(5);

    // Add it to the root panel.
    RootPanel.get().add(lb);
}

public void onChangeBody(ListBox lb) {
    System.out.println(lb.getValue(lb.getSelectedIndex()));
}