Name: gm110360 Date: 08/07/2002


FULL PRODUCT VERSION :
java version "1.4.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)

FULL OPERATING SYSTEM VERSION : Windows NT Workstation 4.0
(Build 1381: Service Pack 6) with Service Pack 6a



A DESCRIPTION OF THE PROBLEM :
Documentation does not state that applet cannot call
getParameters() before init() is called. Calling init in
constructor will cause a NullPointerException in
Applet.java. The reason for failure is because Applet.java
requires the "stub" variable to be non-null before this
method is called. Instead this method (and numerous others)
should follow the code in isActive() in Applet.java.
Applets should *not* have to wrap the getParameter call in
a try...catch block.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Create a new applet by extenting javax.swing.JApplet.
2. In the applet's constructor, call getParameters
("SomeParam").
3. Compile and test the applet. It will *always* fail.

EXPECTED VERSUS ACTUAL BEHAVIOR :
Applet should not fail. getParameters should return null if
the "stub" variable is null.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.NullPointerException
        at java.applet.Applet.getParameter(Applet.java:158)
        at TestingParamApplet.<init>(TestingParamApplet.java:22)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstruct
orAccessorImpl.java:39)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingC
onstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
        at java.lang.Class.newInstance0(Class.java:296)
        at java.lang.Class.newInstance(Class.java:249)
        at sun.applet.AppletPanel.createApplet(AppletPanel.java:548)
        at sun.applet.AppletPanel.runLoader(AppletPanel.java:477)
        at sun.applet.AppletPanel.run(AppletPanel.java:290)
        at java.lang.Thread.run(Thread.java:536)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class TestingParamApplet extends javax.swing.JApplet {

    public TestingParamApplet() {
        String test = getParameter("TestParam");
    }
    
    public void init() {
        this.text.setText(getParameter("TestParam"));
    }
}
---------- END SOURCE ----------

CUSTOMER WORKAROUND :
DO NOT call getParameter in your constructor. Either call
it in init or create a timer in your construtor that fires
every so often (maybe 50 milliseconds) and checks isActive
() before calling getParameter
(Review ID: 153926)
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