JComponent.isShowing（）和isDisplayable（）之间的区别 [英] Difference between JComponent.isShowing() and isDisplayable()
问题描述
Component.isDisplayable（） ？我想用它们来决定我应该停止/启动一个Timer。
What's the difference between Component.isShowing() and Component.isDisplayable()? I want to use them to decide wheter I should stop/start a Timer.
推荐答案
一个组件
isShowing（） when
确定此组件是否在屏幕上显示。这意味着
组件必须是可见的，并且它必须位于
可见并显示的容器中。
Determines whether this component is showing on screen. This means that the component must be visible, and it must be in a container that is visible and showing.
isShowing（）是递归的并检查所有父组件，但是 isDisplayable（）和 isVisible（）仅验证组件的状态，而不验证其父级的状态。
isShowing() is recursive and checks all parent components, too, but isDisplayable() and isVisible() verify only the state of the component, not that state of its parents.
这意味着您的组件当前显示在框架，面板等屏幕上。
setVisible（true） - > isShowing（）返回true（大多数情况下）
setVisible（false） - > isShowing（）返回false（在所有情况下）
This means that your component is currently showing on the screen within a Frame, Panel, etc.
setVisible(true) --> isShowing() returns true (in most cases)
setVisible(false) --> isShowing() returns false (in all cases)
isDisplayable（） when
确定此组件是否可显示。当组件连接到本机屏幕资源时，该组件可以显示
。
Determines whether this component is displayable. A component is displayable when it is connected to a native screen resource.
当一个组件被添加到可显示的
包含层次结构中或者当其包含层次结构为
displayable时，该组件可显示。当
祖先窗口打包或可见时，可以显示包含层次结构。
A component is made displayable either when it is added to a displayable containment hierarchy or when its containment hierarchy is made displayable. A containment hierarchy is made displayable when its ancestor window is either packed or made visible.
组件从$ b中删除时不可显示$ b可显示的包含层次结构或当其包含层次结构为
时不可显示。当
其祖先窗口被释放时，包含层次结构将无法显示。
A component is made undisplayable either when it is removed from a displayable containment hierarchy or when its containment hierarchy is made undisplayable. A containment hierarchy is made undisplayable when its ancestor window is disposed.
这意味着您的组件处于以下状态：它可以显示在屏幕上，但不需要当前显示在屏幕上，以显示可显示的状态。例如，即使之前在组件上调用 setVisible（false）（因此组件不可见）组件仍然是可显示和 isDisplayable（）将返回true。
This means that your component is in a state where it can be shown on the screen but it doesn't need to be currently shown on the screen to be in a displayable state. E.g., even if setVisible(false) was called on the component before (so the component is "invisible") the component is still displayable and isDisplayable() will return true.
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