PVS Studio throws V3125: The 'control.Parent' object was used after it was verified against null. Check lines: 11, 9.
using System.Windows.Forms;
namespace V3125_False_Positive
{
static class Program
{
static void Main()
{
if (new Control() is Control control && control.Parent != null)
{
string parentname = control.Parent.Name;
}
}
}
}
Is this a false positive?
Indeed, this is a false positive. We'll look into it and try fixing it for the next release (actually, for the release after the next one, as we are planning to release a new version in about a week, so the fix will not make it).
Thanks for the tip!
I want to implement a insertion method for a Binary search tree, and come up with a solution below. I know there are plenty of code examples but I wonder what is the problem in my implementation? Or is there a problem? When I had traced it I thought I have missed something.
public void insertBST(Node<Double> head, int value){
if (head == null){
head = new Node<Double>(value);
return;
}
else {
if (head.getValue() > value)
insertBST(head.getLeft(), value);
else
insertBST(head.getRight(), value);
}
}
When you reassign a passed parameter, you're only changing the local variable, not the value passed to the function. You can read this question for more information - Is Java "pass-by-reference"? This is Java, right? Either way, a similar argument likely applies.
This is the problem with this line of code:
head = new Node<Double>(value);
You aren't changing the value passed into the function, so you never add to the tree.
You have two alternatives here, either the option presented by amdorra, or returning the current node:
public void insertBST(Node<Double> current, int value)
{
if (current == null)
{
return new Node<Double>(value);
}
else
{
if (head.getValue() > value)
head.setLeft(insertBST(head.getLeft(),value));
else
head.setRight(insertBST(head.getRight(),value));
return current;
}
}
To call the function, you can simply say:
root = insertBST(root, value);
With alternatives, the root will have to be handled as a special case.
at the beginning of you function you are adding the new Node to a part you will never have access to outside this function
so i will assume that your Node class looks like the following
Class Node{
private Node left;
private Node right;
//constructor, setters and getters and stuff
}
you could modify your code to look like the following:
if (head.getValue() > value){
if(head.getLeft == null) {
head.setLeft(new Node<Double>(value));
return;
}
insertBST(head.getLeft(),value);
}
else{
if(head.getRight == null) {
head.setRight(new Node<Double>(value));
return;
}
insertBST(head.getRight(),value);
}
you should also remove this part if (head==null) and always make sure you are sending a valid Node to the first call
i seem to have a nullPointerException without any reason, could you please review piece of my code and tell me your opinion?
This is the class and the constructor that i am calling on another class in order to get a label randomly (using the shuffle, which is randomizing as well) from a linked list.
here is the
public class RandomHeuristic {
GameInterface game;
JLabel randomLabel;
public JLabel RandomHeuristic() {
randomLabel = (JLabel) game.labels.getFirst();
int counter = 0;
do {
Collections.shuffle(game.labels);
randomLabel = (JLabel) game.labels.getFirst();
counter++;
if (counter == 100) {
break;
}
/*
* Debugging
* System.out.println(randomLabel.getText());
*/
} while (randomLabel != null && game.isLegalMove(randomLabel) == false);
//Retrieves and removes the head (first element) of this list.
if(randomLabel == null){
RandomHeuristic();
}
//game.labels.remove(randomLabel);
return randomLabel;
}
}
And here is where i am calling the constructor, the playHeuristicMove() is expecting a JLabel i checked it on debugging that is working correctly, though i still get a nullPointer Exception when i call it. randomHeuristicOne is created on the same class like this: RandomHeuristic randomHeuristicOne;
playHeuristicMove(randomHeuristicOne.RandomHeuristic());
Perhaps you want to take a look at your game GameInterface object it seems it's never been instantiated
I know this has been an issue for a while now, and checked all previously answers I could get, but still this one doesn't work.
The object 'crew' represents crewmembers with ranks and other items. The comparison should be made by comparing 'assigned_rank', an int value, and if this value is equal in both instances, then 'is_trainer', a boolean, should make the difference.
This method worked great as long as it was running with java < 7. But since Java 7 I keep getting this one:
java.lang.IllegalArgumentException: Comparison method violates its general contract!
at java.util.ComparableTimSort.mergeLo(ComparableTimSort.java:714)
at java.util.ComparableTimSort.mergeAt(ComparableTimSort.java:451)
at java.util.ComparableTimSort.mergeCollapse(ComparableTimSort.java:376)
at java.util.ComparableTimSort.sort(ComparableTimSort.java:182)
at java.util.ComparableTimSort.sort(ComparableTimSort.java:146)
at java.util.Arrays.sort(Arrays.java:472)
at java.util.Collections.sort(Collections.java:155)
at dormas_flightlog.Query.getCrew(Query.java:714)
Here is the source, where some potentially dangerous parts have allready been out-commented, but it still does not work:
public class crew implements Serializable, Comparable<crew> {
private static final long serialVersionUID = 36L;
private int flightID = 0;
private int assigned_rank = 25;
private boolean is_trainer = false;
...
#Override
public int compareTo(crew him) {
int myRank = this.getAssigned_rank();
int hisRank = him.assigned_rank;
if (this == him) {
return 0;
}
if (myRank > hisRank) {
return 1;
}
if (myRank < hisRank) {
return -1;
}
if (myRank == hisRank) {
// if (is_trainer && !o.is_trainer) {
// i = 1;
// }
// if (!is_trainer && o.is_trainer) {
// i = -1;
// }
// if (is_trainer && o.is_trainer) {
// i = 0;
// }
// if (!is_trainer && !o.is_trainer) {
// i = 0;
// }
return 0;
}
return 0;
}
#Override
public int hashCode() {
int hash = 7;
hash = 31 * hash + this.assigned_rank;
hash = 31 * hash + (this.is_trainer ? 1 : 0);
return hash;
}
#Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
int myRank = this.getAssigned_rank();
int hisRank = 0;
if (o instanceof crew) {
crew him = (crew) o;
hisRank = him.assigned_rank;
} else {
return false;
}
if (myRank > hisRank) {
return false;
}
if (myRank < hisRank) {
return false;
}
if (myRank == hisRank) {
// if (is_trainer && !o.is_trainer) {
// i = 1;
// }
// if (!is_trainer && o.is_trainer) {
// i = -1;
// }
// if (is_trainer && o.is_trainer) {
// i = 0;
// }
// if (!is_trainer && !o.is_trainer) {
// i = 0;
// }
return true;
}
return false;
}
}
Implementing equals() was just a try to solve this problem. The given exception comes with or without equals(). I cannot see how the compareTo-method violates its contract. Any help is greatly appreciated....one day this code has to work with java 7 and I don't know how...
Thanks
see this:
From http://www.oracle.com/technetwork/java/javase/compatibility-417013.html#source
Area: API: Utilities Synopsis: Updated sort behavior for Arrays and
Collections may throw an IllegalArgumentException
Description: The sorting algorithm used by java.util.Arrays.sort and
(indirectly) by java.util.Collections.sort has been replaced. The new
sort implementation may throw an IllegalArgumentException if it detects
a Comparable that violates the Comparable contract. The previous
implementation silently ignored such a situation. If the previous
behavior is desired, you can use the new system
property java.util.Arrays.useLegacyMergeSort, to restore previous
mergesort behavior.
Nature of Incompatibility: behavioral
RFE: 6804124
For more detailed info, see the bug database reference here.
maybe you just have NaN values which you compare through Collections.sort(...), this has been a problem to me and I got that exception even having right implementation of compare(obj1, obj2) method! Check that!
I was able to solve this error cause it was a bug in jdk7.
here I found the solution:
"Comparison method violates its general contract!" - TimSort and GridLayout
Basically i just had to add the
JAVA_OPTS="$JAVA_OPTS -Djava.util.Arrays.useLegacyMergeSort=true"
to my jboss
Unfortunately, none of the solutions work for Android. TimSort is used deep in Android's ViewGroup relating to addChildrenForAccessibility that shows up under Java 7 & 8. No user code is involved in any comparison.
From other reports, it is related to having RelativeLayout with overlapping items as is commonly done. For example, a TextView that appears over an Image, or two items at the same location, where you only set one visible at a time.
https://code.google.com/p/android/issues/detail?id=55933
I've not found any way around the bug. You can't set a -Djava option in Android Studio or Eclipse (at least that I could find). Forcing use of Java 1.6 should work, but doesn't. Seems like Amazon's newer Fire tablets and phones are far more sensitive to this bug than other devices.
There are rumors Java 9 will have a fix such as a run-time option that works, but with a bug that's been around for years, I have doubts it will ever be fixed - especially considering the animosity between Oracle and Google. Any yes, perhaps the bug is really deep in the Android code and should be fixed there. With more than a billion devices out there, that's not a viable solution for all the existing devices.
I am getting some errors thrown in my code when I open a Windows Forms form in Visual Studio's designer. I would like to branch in my code and perform a different initialization if the form is being opened by designer than if it is being run for real.
How can I determine at run-time if the code is being executed as part of designer opening the form?
if (System.ComponentModel.LicenseManager.UsageMode == System.ComponentModel.LicenseUsageMode.Designtime)
{
// Design time logic
}
To find out if you're in "design mode":
Windows Forms components (and controls) have a DesignMode property.
Windows Presentation Foundation controls should use the IsInDesignMode attached property.
The Control.DesignMode property is probably what you're looking for. It tells you if the control's parent is open in the designer.
In most cases it works great, but there are instances where it doesn't work as expected. First, it doesn't work in the controls constructor. Second, DesignMode is false for "grandchild" controls. For example, DesignMode on controls hosted in a UserControl will return false when the UserControl is hosted in a parent.
There is a pretty easy workaround. It goes something like this:
public bool HostedDesignMode
{
get
{
Control parent = Parent;
while (parent!=null)
{
if(parent.DesignMode) return true;
parent = parent.Parent;
}
return DesignMode;
}
}
I haven't tested that code, but it should work.
The most reliable approach is:
public bool isInDesignMode
{
get
{
System.Diagnostics.Process process = System.Diagnostics.Process.GetCurrentProcess();
bool res = process.ProcessName == "devenv";
process.Dispose();
return res;
}
}
The most reliable way to do this is to ignore the DesignMode property and use your own flag that gets set on application startup.
Class:
public static class Foo
{
public static bool IsApplicationRunning { get; set; }
}
Program.cs:
[STAThread]
static void Main()
{
Foo.IsApplicationRunning = true;
// ... code goes here ...
}
Then just check the flag whever you need it.
if(Foo.IsApplicationRunning)
{
// Do runtime stuff
}
else
{
// Do design time stuff
}
I had the same problem in Visual Studio Express 2013. I tried many of the solutions suggested here but the one that worked for me was an answer to a different thread, which I will repeat here in case the link is ever broken:
protected static bool IsInDesigner
{
get { return (Assembly.GetEntryAssembly() == null); }
}
The devenv approach stopped working in VS2012 as the designer now has its own process. Here is the solution I am currently using (the 'devenv' part is left there for legacy, but without VS2010 I am not able to test that though).
private static readonly string[] _designerProcessNames = new[] { "xdesproc", "devenv" };
private static bool? _runningFromVisualStudioDesigner = null;
public static bool RunningFromVisualStudioDesigner
{
get
{
if (!_runningFromVisualStudioDesigner.HasValue)
{
using (System.Diagnostics.Process currentProcess = System.Diagnostics.Process.GetCurrentProcess())
{
_runningFromVisualStudioDesigner = _designerProcessNames.Contains(currentProcess.ProcessName.ToLower().Trim());
}
}
return _runningFromVisualStudioDesigner.Value;
}
}
/// <summary>
/// Are we in design mode?
/// </summary>
/// <returns>True if in design mode</returns>
private bool IsDesignMode() {
// Ugly hack, but it works in every version
return 0 == String.CompareOrdinal(
"devenv.exe", 0,
Application.ExecutablePath, Application.ExecutablePath.Length - 10, 10);
}
System.Diagnostics.Debugger.IsAttached
It's hack-ish, but if you're using VB.NET and when you're running from within Visual Studio My.Application.Deployment.CurrentDeployment will be Nothing, because you haven't deployed it yet. I'm not sure how to check the equivalent value in C#.
using (System.Diagnostics.Process process = System.Diagnostics.Process.GetCurrentProcess())
{
bool inDesigner = process.ProcessName.ToLower().Trim() == "devenv";
return inDesigner;
}
I tried the above code (added a using statement) and this would fail on some occasions for me. Testing in the constructor of a usercontrol placed directly in a form with the designer loading at startup. But would work in other places.
What worked for me, in all locations is:
private bool isDesignMode()
{
bool bProcCheck = false;
using (System.Diagnostics.Process process = System.Diagnostics.Process.GetCurrentProcess())
{
bProcCheck = process.ProcessName.ToLower().Trim() == "devenv";
}
bool bModeCheck = (System.ComponentModel.LicenseManager.UsageMode == System.ComponentModel.LicenseUsageMode.Designtime);
return bProcCheck || DesignMode || bModeCheck;
}
Maybe a bit overkill, but it works, so is good enough for me.
The success in the example noted above is the bModeCheck, so probably the DesignMode is surplus.
You check the DesignMode property of your control:
if (!DesignMode)
{
//Do production runtime stuff
}
Note that this won't work in your constructor because the components haven't been initialized yet.
When running a project, its name is appended with ".vshost".
So, I use this:
public bool IsInDesignMode
{
get
{
Process p = Process.GetCurrentProcess();
bool result = false;
if (p.ProcessName.ToLower().Trim().IndexOf("vshost") != -1)
result = true;
p.Dispose();
return result;
}
}
It works for me.
I'm not sure if running in debug mode counts as real, but an easy way is to include an if statement in your code that checkes for System.Diagnostics.Debugger.IsAttached.
If you created a property that you don't need at all at design time, you can use the DesignerSerializationVisibility attribute and set it to Hidden. For example:
protected virtual DataGridView GetGrid()
{
throw new NotImplementedException("frmBase.GetGrid()");
}
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
public int ColumnCount { get { return GetGrid().Columns.Count; } set { /*Some code*/ } }
It stopped my Visual Studio crashing every time I made a change to the form with NotImplementedException() and tried to save. Instead, Visual Studio knows that I don't want to serialize this property, so it can skip it. It only displays some weird string in the properties box of the form, but it seems to be safe to ignore.
Please note that this change does not take effect until you rebuild.
We use the following code in UserControls and it does the work. Using only DesignMode will not work in your app that uses your custom user controls as pointed out by other members.
public bool IsDesignerHosted
{
get { return IsControlDesignerHosted(this); }
}
public bool IsControlDesignerHosted(System.Windows.Forms.Control ctrl)
{
if (ctrl != null)
{
if (ctrl.Site != null)
{
if (ctrl.Site.DesignMode == true)
return true;
else
{
if (IsControlDesignerHosted(ctrl.Parent))
return true;
else
return false;
}
}
else
{
if (IsControlDesignerHosted(ctrl.Parent))
return true;
else
return false;
}
}
else
return false;
}
Basically the logic above boils down to:
public bool IsControlDesignerHosted(System.Windows.Forms.Control ctrl)
{
if (ctrl == null) return false;
if (ctrl.Site != null && ctrl.Site.DesignMode) return true;
return IsControlDesignerHosted(ctrl.Parent);
}
If you are in a form or control you can use the DesignMode property:
if (DesignMode)
{
DesignMode Only stuff
}
I found the DesignMode property to be buggy, at least in previous versions of Visual Studio. Hence, I made my own using the following logic:
Process.GetCurrentProcess().ProcessName.ToLower().Trim() == "devenv";
Kind of a hack, I know, but it works well.
System.ComponentModel.Component.DesignMode == true
To solve the problem, you can also code as below:
private bool IsUnderDevelopment
{
get
{
System.Diagnostics.Process process = System.Diagnostics.Process.GetCurrentProcess();
if (process.ProcessName.EndsWith(".vshost")) return true;
else return false;
}
}
Here's another one:
//Caters only to thing done while only in design mode
if (App.Current.MainWindow == null){ // in design mode }
//Avoids design mode problems
if (App.Current.MainWindow != null) { //applicaiton is running }
After testing most of the answers here, unfortunately nothing worked for me (VS2015).
So I added a little twist to JohnV's answer, which didn't work out of the box, since DesignMode is a protected Property in the Control class.
First I made an extension method which returns the DesignMode's Property value via Reflection:
public static Boolean GetDesignMode(this Control control)
{
BindingFlags bindFlags = BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Static;
PropertyInfo prop = control.GetType().GetProperty("DesignMode", bindFlags);
return (Boolean)prop.GetValue(control, null);
}
and then I made a function like JohnV:
public bool HostedDesignMode
{
get
{
Control parent = Parent;
while (parent != null)
{
if (parent.GetDesignMode()) return true;
parent = parent.Parent;
}
return DesignMode;
}
}
This is the only method that worked for me, avoiding all the ProcessName mess, and while reflection should not be used lightly, in this case it did all the difference! ;)
EDIT:
You can also make the second function an extension method like this:
public static Boolean IsInDesignMode(this Control control)
{
Control parent = control.Parent;
while (parent != null)
{
if (parent.GetDesignMode())
{
return true;
}
parent = parent.Parent;
}
return control.GetDesignMode();
}
For WPF (hopefully this is useful for those WPF people stumbling upon this question):
if (System.ComponentModel.DesignerProperties.GetIsInDesignMode(new DependencyObject()))
{
}
GetIsInDesignMode requires a DependencyObject. If you don't have one, just create one.
/// <summary>
/// Whether or not we are being run from the Visual Studio IDE
/// </summary>
public bool InIDE
{
get
{
return Process.GetCurrentProcess().ProcessName.ToLower().Trim().EndsWith("vshost");
}
}
Here's a flexible way that is adaptable to where you compile from as well as whether or not you care which mode you're in.
string testString1 = "\\bin\\";
//string testString = "\\bin\\Debug\\";
//string testString = "\\bin\\Release\\";
if (AppDomain.CurrentDomain.BaseDirectory.Contains(testString))
{
//Your code here
}