java - How to efficiently dispose resources in SWT?

Question

I have a simple SWT application which contains menus and controls. I have Text, tables, and trees available in the application, and I need to explicitly call the dispose method to clear the current object and give space for displaying other widgets on the screen. The system crashes when I call the dispose method if the widget is not already activated. Is there any better approach available to dispose an active widget to give room for another widget?

Answer 1

如果您确实需要处理小部件，您可以保留已添加项目的列表。仅处置已添加到列表中的项目。

所以我会用我的主容器类覆盖 JFrame，并有一两个方法将控件添加到列表中。（如果您需要对它们的去向进行特殊控制，您也可以在添加控制方法中传递一个选项类）

class MainContainer extends JFrame {
    private List<JComponent> currentComponents = new ArrayList<JComponent>();

    public void addControl(JComponent newComp) {
        // -- add it to the JFrame --
        ...

        // -- make a note that it is on --
        currentComponents.add(newComp);
    }

    public void removeControl(JComponent oldComp) {
        // -- check if it is in the list --
        if (currentComponents.contains(oldComp)) {
            // -- remove it from the JFrame --
            ...

            // -- remove it from the list --
            currentComponents.remove(oldComp);
        }
    }
}

或者，您的所有组件都可以被覆盖并显示一个标志

private boolean isDisplayed();

方法和私有 setDisplayed(boolean state); 这样，当您进行添加时，您将显示状态设置为 true，而当您进行删除时，只有在显示状态为 true 时才执行此操作，然后将状态设置为 false。