I would like to modify a label. I create it at the top:
JLabel curStatus;
and then in a method that starts up all of the gui...
curStatus = new JLabel("");
jfrm.add(curStatus);
then for the method that takes a string, and puts it as the status of the jlabel:
public void setCurStatus(String inCurStatus) {
curStatus.setText("hi!"); <<< ERROR ON THIS LINE...
curStatus.setVisible(true);
}
I get this error:
Exception in thread "main" java.lang.NullPointerException
from the code snippet, it is clear that jLabel is null when you set the text.
Obvious and only possible reason is : your GUI initialization code is not being executed before setting text. There cant be other reason at all.
You look again, and make sure that those initializations happen at the very first (call it in the top of constructor)
either remove the #param from the method or use
curStatus.setText(inCurStatus); // instead of curStatus.setText("Hi");
and pass "Hi" as an argument when you call the method.
Related
I have written an AST transform that creates a setter for a JPA mapped property (it both sets the local field and calls setOwner on the other end of the relationship):
private static void createSetter(FieldNode field) {
Parameter parameter = GeneralUtils.param(field.getType(), field.getName());
BlockStatement body = new BlockStatement();
body.addStatement(assignS(fieldX(field), varX(parameter)));
MethodCallExpression setterCall = callX(varX(parameter), "setOwner", varX("this", field.getDeclaringClass()));
setterCall.setType(ClassHelper.VOID_TYPE);
body.addStatement(stmt(setterCall));
MethodNode method = new MethodNode(setterName(field.getName()), ACC_PUBLIC, ClassHelper.VOID_TYPE, new Parameter[] {parameter}, ClassNode.EMPTY_ARRAY, body);
field.getDeclaringClass().addMethod(method);
}
This works, but the generated method has a strange null statement at the end as disassembled by JD-GUI (in addition to an odd local variable):
public void setMore(Simple_MoreStuff more) {
Simple_MoreStuff localSimple_MoreStuff = more;
this.more = localSimple_MoreStuff;
more.setOwner(this);
null;
}
It doesn't seem to affect the actual correctness, but it's odd, and it seems like a bug. In MethodCallExpression, I found this comment but don't know if it relates, since my method is in fact void (I explicitly set it above, and it makes no difference):
//TODO: set correct type here
// if setting type and a methodcall is the last expression in a method,
// then the method will return null if the method itself is not void too!
// (in bytecode after call: aconst_null, areturn)
Is there a way to keep the generated method from having the spurious null?
I have not looked at JD-GUI, so I cannot tell how capable this tool is in understanding bytecode, that does not come from Java. But in general disassemblers can only somewhat show what Java code in that case might look like, by no means it is supposed to show correct code from a non-Java language. So better do not expect correct Java code if you disassemble Groovy.
In this case I suspect that JD-GUI stumbles over a workaround we have not gotten rid of yet. In several cases we add at the method end dead code, the const_null, areturn you have noticed. We do this because of problems with the verifier if a bytecode label is used at the end of a method. And since the dead code does not influence correctness we are currently using this solution.
I'm trying to perform some basic logic on my application which checks the entities position to call an enter/exit method however I'm getting some strange results:
Contains false - Compare true
Where the following method prints the results
#Override
public void checkLocation(Player player) {
System.out.println("Contains " + contains(player) + " - Compare ${inLocation(player.position)}");
}
The contains boolean:
#Override
public boolean contains(Player player) {
return inLocation(player.position);
}
I don't understand how contains(player) returns false, while the inLocation(player.position) returns true? Really stomping on my understanding of how things work.
The code is in groovy. ${var} is just groovy's way of concatenating.
Depending on the context of your code it is possible that groovy's contains method is being called on the class/controller/service that this code exists in, instead of calling your defined contains method. Maybe it is implicitly calling
this.contains(player)
Try changing your method name to "hasPlayer()" or add a println inside your contains method to ensure that code is being called.
I have a member named _label as an ivar member in class :
#interface CCHelloWorldLayer : CCLayer
{
CCLabelBMFont *_label;
}
in another codeblock: initializing with this line:
_label = [CCLabelBMFont labelWithString:#"Testing " fntFile:fntName];
question is this:
if I want to modify its text what Should I do ?
I dont see any method like:
[_label setString:#"Well.there is no such a method"];
if I do
_label = [CCLabelBMFont labelWithString:#"Testing " fntFile:fntName];
_label = [CCLabelBMFont labelWithString:#"Well.there is no such a method"
fntFile:fntName];
is first memory allocation autoreleasing it self ?
is it safe to recall labelWithString method repeately ?
(note:I dont use ARC in test project.and I wont.)
thanks in advice
There is a setString method but it appears to be "private". The +labelWithString method does create an autorelease object and can be used repeatedly. It looks like it creates a texture, so you would want to create a new texture each time (as opposed to trying to modify it).
In general though, if you want the autoreleased object to stick around, you should retain it and release it when you're done.
[_label setString:#"Well.there is no such a method"];
This method exists and you can call it like that. Try it, it works.
The method is not declared in the class but in CCLabelProtocol.
I have a textfield (lower level) a call a function that call a higher level form that contains a datafield to pick up a date and display it in my textfield lowerlevel.
The problem is I cannot get back to my textfield (lower level) since the datefield appears
public void formdatepicker() {
final javax.microedition.lcdui.Command CONFIRM_COMMAND
= new javax.microedition.lcdui.Command("OK",
javax.microedition.lcdui.Command.OK, 1);
javax.microedition.lcdui.Command CANCEL_COMMAND
= new javax.microedition.lcdui.Command("Cancel",
javax.microedition.lcdui.Command.CANCEL, 2);
final DateField datefield = new DateField("Pick a date", DateField.DATE);
form.append(datefield);
form.addCommand(CONFIRM_COMMAND);
form.addCommand(CANCEL_COMMAND);
form.setCommandListener(new CommandListener() {
public void commandAction(javax.microedition.lcdui.Command c, Displayable d) {
if (c == CONFIRM_COMMAND) {
Date date = datefield.getDate();
display.setCurrent(null);// try to hide the current form to get
}
}
});
Display.getInstance().getJ2MEDisplay().setCurrent(form);
Your mistake is wrong assumption about what setCurrent(null) does. Per your question and code snippet, it looks like you expect it to somehow show the screen that has been displayed prior to form. It doesn't, see the exaplanation in the API javadocs (available online):
The application may pass null as the argument to setCurrent(). This does not have the effect of setting the current Displayable to null; instead, the current Displayable remains unchanged. However, the application management software may interpret this call as a request from the application that it is requesting to be placed into the background...
If you want to use setCurrent(Displayable) to show some screen instead of current one, you need to pass this screen as an argument to setCurrent.
For the sake of completeness, note that there is another version of setCurrent that accepts two parameters, first of which is Alert, which works a bit differently, but it is not applicable in your case because you use Form not Alert.
symfony getLayout does not seem to work when layout is set via view.yml. Is there anyway to get this within the controller's action class method
I recently needed this. You can do it but you just need to return the entire view.yml contents as an array:
$view_array = sfViewConfigHandler::getConfiguration(array(sfConfig::get('sf_app_config_dir').'/view.yml'));
Just adjust the relative path from sf_app_config_dir (or use another marker) to get what you need.
It's not a trivial task. The view.yml, is not in the "scope" of the action.
Maybe, you can use setLayout in your action rather then in view.yml.
if you can't, for some reasons... you can try this method to reach datas in view.yml:
Is it possible to get a value from view.yml in an action
Execute the following code in the action. It works for both cases, layout set in the action or in the view.yml.
$controller = $this->getContext()->getController();
$view = $controller->getView($this->getModuleName(), $this->getActionName(), 'Success'); // viewName == 'Success' (default)
$layout_name = $view->getDecoratorTemplate(); // e.g expected: layout.php
Let us know if it works for you.