Java - classe ajouter méthode lève StackOverflowError sur déclaration package - Stack Overflow

I am producing a library for personal use; in this particular class, extending JPanel, and my code still for some random reason, produces a StackOverflowError any tips?

public class XJPanel extends JPanel
{
    static boolean isManaged = false;

    public XJPanel() {

    }

    public XJPanel(LayoutManager arg0) {
        super(arg0);
        isManaged = true;
    }

    public XJPanel(boolean arg0) {
        super(arg0);
        // TODO Auto-generated constructor stub
    }

    public XJPanel(LayoutManager arg0, boolean arg1) {
        super(arg0, arg1);
        isManaged = true;
    }
    public GridBagConstraints getConstraints()
    {
        if(isManaged = true)
        {
            return new GridBagConstraints();
        }
        throw new NullPointerException("No Layout Manager Found");
    }


    /*
    public XJPanel add(Component arg0)
    {
        JPanel p = getRoot();
        p.add(arg0);
        return null;
    }

    private JPanel getRoot() {
        return this;
    }*/

the error it reads is exactly as follows. I think I understand what a StackOverflowError is, but I'd like to know why the error message includes the package declaration -- it contains no code, so... why?

Exception in thread "main" java.lang.StackOverflowError
at javar.swing.XJPanel.getRoot(XJPanel.java:61)
at javar.swing.XJPanel.add(XJPanel.java:55)
at javar.swing.XJPanel.add(XJPanel.java:1)
...
at javar.swing.XJPanel.add(XJPanel.java:56)
at javar.swing.XJPanel.add(XJPanel.java:1)
at javar.swing.XJPanel.add(XJPanel.java:56)

the javar.swing.XJPanel.add(XJPanel.java:1) being my package declaration.

Note:

I'm sorry for being such a jerk, @SimonC I guess I had a case of the grumps, I'm well rested now and ready to shape up.

You have:

public XJPanel add(Component arg0)
{
    JPanel p = getRoot();
    p.add(arg0);
    return null;
}

private JPanel getRoot() {
    return this;
}

This is, of course, infinitely recursive (as your stack trace clearly indicates, and as a quick glance at the code shows -- try running through it in your head).

See also the documentation for StackOverflowError, which states:

Thrown when a stack overflow occurs because an application recurses too deeply.

You have implemented the add method recursive.

public XJPanel add(Component arg0) {
    JPanel p = getRoot();
    p.add(arg0);
    return null;
}

private JPanel getRoot() {
    return this;
}

is essentially equivalent to

public XJPanel add(Component arg0)
{
    this.add(arg0);
    return null;
}

Which would be unbounded infinite recursion, which would obviously give a stack overflow error.

The other questions answer why a StackOverflowError is being thrown (not randomly of course), but to answer your specific question of why your package name is included in the stack trace: because that's the package name of the last methods being called before the stack overflowed.

I am producing a library for personal use; in this particular class, extending JPanel, and my code still for some random reason, produces a StackOverflowError any tips?

public class XJPanel extends JPanel
{
    static boolean isManaged = false;

    public XJPanel() {

    }

    public XJPanel(LayoutManager arg0) {
        super(arg0);
        isManaged = true;
    }

    public XJPanel(boolean arg0) {
        super(arg0);
        // TODO Auto-generated constructor stub
    }

    public XJPanel(LayoutManager arg0, boolean arg1) {
        super(arg0, arg1);
        isManaged = true;
    }
    public GridBagConstraints getConstraints()
    {
        if(isManaged = true)
        {
            return new GridBagConstraints();
        }
        throw new NullPointerException("No Layout Manager Found");
    }


    /*
    public XJPanel add(Component arg0)
    {
        JPanel p = getRoot();
        p.add(arg0);
        return null;
    }

    private JPanel getRoot() {
        return this;
    }*/

the error it reads is exactly as follows. I think I understand what a StackOverflowError is, but I'd like to know why the error message includes the package declaration -- it contains no code, so... why?

Exception in thread "main" java.lang.StackOverflowError
at javar.swing.XJPanel.getRoot(XJPanel.java:61)
at javar.swing.XJPanel.add(XJPanel.java:55)
at javar.swing.XJPanel.add(XJPanel.java:1)
...
at javar.swing.XJPanel.add(XJPanel.java:56)
at javar.swing.XJPanel.add(XJPanel.java:1)
at javar.swing.XJPanel.add(XJPanel.java:56)

the javar.swing.XJPanel.add(XJPanel.java:1) being my package declaration.

Note:

I'm sorry for being such a jerk, @SimonC I guess I had a case of the grumps, I'm well rested now and ready to shape up.

You have:

public XJPanel add(Component arg0)
{
    JPanel p = getRoot();
    p.add(arg0);
    return null;
}

private JPanel getRoot() {
    return this;
}

This is, of course, infinitely recursive (as your stack trace clearly indicates, and as a quick glance at the code shows -- try running through it in your head).

See also the documentation for StackOverflowError, which states:

Thrown when a stack overflow occurs because an application recurses too deeply.

You have implemented the add method recursive.

public XJPanel add(Component arg0) {
    JPanel p = getRoot();
    p.add(arg0);
    return null;
}

private JPanel getRoot() {
    return this;
}

is essentially equivalent to

public XJPanel add(Component arg0)
{
    this.add(arg0);
    return null;
}

Which would be unbounded infinite recursion, which would obviously give a stack overflow error.

The other questions answer why a StackOverflowError is being thrown (not randomly of course), but to answer your specific question of why your package name is included in the stack trace: because that's the package name of the last methods being called before the stack overflowed.

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