Java – How to get all elements inside a JFrame

javajcomponentswing

I have this code to get all the elements I need and do some processing. The problem is I need to specify every panel I have to get the elements inside it.

for (Component c : panCrawling.getComponents()) {
    //processing
}
for (Component c : panFile.getComponents()) {
    //processing
}
for (Component c : panThread.getComponents()) {
    //processing
}
for (Component c : panLog.getComponents()) {
    //processing
}
//continue to all panels

I want to do something like this and get all the elements without need specefy all the panels names. How I do this. The code below don't get all the elements.

for (Component c : this.getComponents()) {
    //processing
}

Best Answer

You can write a recursive method and recurse on every container:

This site provides some sample code:

public static List<Component> getAllComponents(final Container c) {
    Component[] comps = c.getComponents();
    List<Component> compList = new ArrayList<Component>();
    for (Component comp : comps) {
        compList.add(comp);
        if (comp instanceof Container)
            compList.addAll(getAllComponents((Container) comp));
    }
    return compList;
}

If you only want the components of the immediate sub-components, you could limit the recursion depth to 2.

Related Solutions

Java – How to assert that a certain exception is thrown in JUnit 4 tests

It depends on the JUnit version and what assert libraries you use.

For JUnit5 and 4.13 see answer https://stackoverflow.com/a/2935935/2986984
If you use assertJ or google-truth, see answer https://stackoverflow.com/a/41019785/2986984

The original answer for JUnit <= 4.12 was:

@Test(expected = IndexOutOfBoundsException.class)
public void testIndexOutOfBoundsException() {

    ArrayList emptyList = new ArrayList();
    Object o = emptyList.get(0);

}

Though answer https://stackoverflow.com/a/31826781/2986984 has more options for JUnit <= 4.12.

Reference :

JUnit Test-FAQ

Java – Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop

Iterator.remove() is safe, you can use it like this:

List<String> list = new ArrayList<>();

// This is a clever way to create the iterator and call iterator.hasNext() like
// you would do in a while-loop. It would be the same as doing:
//     Iterator<String> iterator = list.iterator();
//     while (iterator.hasNext()) {
for (Iterator<String> iterator = list.iterator(); iterator.hasNext();) {
    String string = iterator.next();
    if (string.isEmpty()) {
        // Remove the current element from the iterator and the list.
        iterator.remove();
    }
}

Note that Iterator.remove() is the only safe way to modify a collection during iteration; the behavior is unspecified if the underlying collection is modified in any other way while the iteration is in progress.

Source: docs.oracle > The Collection Interface

And similarly, if you have a ListIterator and want to add items, you can use ListIterator#add, for the same reason you can use Iterator#remove — it's designed to allow it.

In your case you tried to remove from a list, but the same restriction applies if trying to put into a Map while iterating its content.

Best Answer

Related Solutions

Java – How to assert that a certain exception is thrown in JUnit 4 tests

Java – Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop

Related Topic