Java Open Jdk Download For Windows 10
Rocki Stenger
A Frame is a top-level window with a title and a border. The size of the frame includes any area designated for the border. The dimensions of the border area may be obtained using the getInsets method. Since the border area is included in the overall size of the frame, the border effectively obscures a portion of the frame, constraining the area available for rendering and/or displaying subcomponents to the rectangle which has an upper-left corner location of (insets.left, insets.top), and has a size of width - (insets.left + insets.right) by height - (insets.top + insets.bottom).
A frame, implemented as an instance of the JFrame class, is a window that has decorations such as a border, a title, and supports button components that close or iconify the window. Applications with a GUI usually include at least one frame. Applets sometimes use frames, as well.
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- The first line of code creates a frame using a constructor that lets you set the frame title. The other frequently used JFrame constructor is the no-argument constructor.
- Next the code specifies what happens when your user closes the frame. The EXIT_ON_CLOSE operation exits the program when your user closes the frame. This behavior is appropriate for this program because the program has only one frame, and closing the frame makes the program useless.See Responding to Window-Closing Events for more information.
By default, window decorations are supplied by the native window system. However, you can request that the look-and-feel provide the decorations for a frame. You can also specify that the frame have no window decorations at all, a feature that can be used on its own, or to provide your own decorations, or with full-screen exclusive mode.
Besides specifying who provides the window decorations, you can also specify which icon is used to represent the window. Exactly how this icon is used depends on the window system or look and feel that provides the window decorations. If the window system supports minimization, then the icon is used to represent the minimized window. Most window systems or look and feels also display the icon in the window decorations. A typical icon size is 16x16 pixels, but some window systems use other sizes.
The following snapshots show three frames that are identical except for their window decorations. As you can tell by the appearance of the button in each frame, all three use the Java look and feel. The first uses decorations provided by the window system, which happen to be Microsoft Windows, but could as easily be any other system running the Java platform.The second and third use window decorations provided by the Java look and feel. The third frame uses Java look and feel window decorations, but has a custom icon.
As the preceding code snippet implies, you must invoke the setDefaultLookAndFeelDecorated method before creating the frame whose decorations you wish to affect. The value you set with setDefaultLookAndFeelDecorated is used for all subsequently created JFrames. You can switch back to using window system decorations by invoking JFrame.setDefaultLookAndFeelDecorated(false). Some look and feels might not support window decorations; in this case, the window system decorations are used.
The full source code for the application that creates the frames pictured above is in FrameDemo2.java. Besides showing how to choose window decorations, FrameDemo2 also shows how to disable all window decorations and gives an example of positioning windows. It includes two methods that create the Image objects used as icons one is loaded from a file, and the other is painted from scratch.
By default, when the user closes a frame onscreen, the frame is hidden. Although invisible, the frame still exists and the program can make it visible again. If you want different behavior, then you need to either register a window listener that handles window-closing events, or you need to specify default close behavior using the setDefaultCloseOperation method. You can even do both.
The argument to setDefaultCloseOperation must be one of the following values, the first three of which are defined in the WindowConstants interface (implemented by JFrame, JInternalPane, and JDialog):
DISPOSE_ON_CLOSE can have results similar to EXIT_ON_CLOSE if only one window is onscreen. More precisely, when the last displayable window within the Java virtual machine (VM) is disposed of, the VM may terminate. See AWT Threading Issues for details.
The default close operation is executed after any window listeners handle the window-closing event. So, for example, assume that you specify that the default close operation is to dispose of a frame. You also implement a window listener that tests whether the frame is the last one visible and, if so, saves some data and exits the application. Under these conditions, when the user closes a frame, the window listener will be called first. If it does not exit the application, then the default close operation disposing of the frame will then be performed.
For more information about handling window-closing events, see How to Write Window Listeners. Besides handling window-closing events, window listeners can also react to other window state changes, such as iconification and activation.
The following tables list the commonly used JFrame constructors and methods. Other methods you might want to call are defined by the java.awt.Frame, java.awt.Window, and java.awt.Component classes, from which JFrame descends.
Because each JFrame object has a root pane, frames have support for interposing input and painting behavior in front of the frame children, placing children on different "layers", and for Swing menu bars. These topics are introduced in Using Top-Level Containers and explained in detail in How to Use Root Panes.
A string, without whitespace, specifying the name of the browsing context the resource is being loaded into. If the name doesn't identify an existing context, a new context is created and given the specified name. The special target keywords, _self, _blank (default), _parent, _top, and _unfencedTop can also be used. _unfencedTop is only relevant to fenced frames.
Indicates that you want the browser to send an Attribution-Reporting-Eligible header along with the open() call. This call must be made with transient activation (i.e. inside a user interaction event handle such as click), within five seconds of user interaction. On the server-side this is used to trigger sending an Attribution-Reporting-Register-Source header in the response to complete registration of an attribution source.
If this feature is enabled, it requests that a minimal popup window be used. The UI features included in the popup window will be automatically decided by the browser, generally including an address bar only.
Note: Requested position (top, left), and requested dimension (width, height) values in windowFeatures will be corrected if any of such requested value does not allow the entire browser popup to be rendered within the work area for applications of the user's operating system. In other words, no part of the new popup can be initially positioned offscreen.
If the browser successfully opens the new browsing context, a WindowProxy object is returned. The returned reference can be used to access properties and methods of the new context as long as it complies with the same-origin policy security requirements.
The Window interface's open() method takes a URL as a parameter, and loads the resource it identifies into a new or existing tab or window. The target parameter determines which window or tab to load the resource into, and the windowFeatures parameter can be used to control to open a new popup with minimal UI features and control its size and position.
Remote URLs won't load immediately. When window.open() returns, the window always contains about:blank. The actual fetching of the URL is deferred and starts after the current script block finishes executing. The window creation and the loading of the referenced resource are done asynchronously.
Modern browsers have strict popup blocker policies. Popup windows must be opened in direct response to user input, and a separate user gesture event is required for each Window.open() call. This prevents sites from spamming users with lots of windows. However, this poses an issue for multi-window applications. To work around this limitation, you can design your applications to:
In some cases, JavaScript is disabled or unavailable and window.open() will not work. Instead of solely relying on the presence of this feature, we can provide an alternative solution so that the site or application still functions.
If JavaScript support is disabled or non-existent, then the user agent will create a secondary window accordingly or will render the referenced resource according to its handling of the target attribute. The goal and the idea are to provide (and not impose) to the user a way to open the referenced resource.
The above code solves a few usability problems related to links opening popups. The purpose of the event.preventDefault() in the code is to cancel the default action of the link: if the event listener for click is executed, then there is no need to execute the default action of the link. But if JavaScript support is disabled or non-existent on the user's browser, then the event listener for click is ignored, and the browser loads the referenced resource in the target frame or window that has the name "WikipediaWindowName". If no frame nor window has the name "WikipediaWindowName", then the browser will create a new window and name it "WikipediaWindowName".
Using "_blank" as the target attribute value will create several new and unnamed windows on the user's desktop that cannot be recycled or reused. Try to provide a meaningful name to your target attribute and reuse such target attribute on your page so that a click on another link may load the referenced resource in an already created and rendered window (therefore speeding up the process for the user) and therefore justifying the reason (and user system resources, time spent) for creating a secondary window in the first place. Using a single target attribute value and reusing it in links is much more user resources friendly as it only creates one single secondary window, which is recycled.
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