使用偏好

Preferences 可用於儲存反映使用者個人應用程式設定的使用者設定，例如他們的編輯器字型，是否更喜歡以全屏模式啟動應用程式，是否選中不再顯示此項核取方塊和事物像那樣。

public class ExitConfirmer {
    private static boolean confirmExit() {
        Preferences preferences = Preferences.userNodeForPackage(ExitConfirmer.class);
        boolean doShowDialog = preferences.getBoolean("showExitConfirmation", true); // true is default value

        if (!doShowDialog) {
            return true;
        }

        //
        // Show a dialog here...
        //
        boolean exitWasConfirmed = ...; // whether the user clicked OK or Cancel
        boolean doNotShowAgain = ...; // get value from "Do not show again" checkbox

        if (exitWasConfirmed && doNotShowAgain) {
            // Exit was confirmed and the user chose that the dialog should not be shown again
            // Save these settings to the Preferences object so the dialog will not show again next time
            preferences.putBoolean("showExitConfirmation", false);
        }

        return exitWasConfirmed;
    }

    public static void exit() {
        if (confirmExit()) {
            System.exit(0);
        }
    }
}