带内循环返回的Java for-each循环未按预期工作

Question

Following Java code is not working in Android as expected whether it is compiled with JDK 1.6 or 1.7. When the "if statement" is evaluated true, "found is assigned to variable mState, however the next statement "return ext;" is not being executed. Instead it executed the last statement "return null;". Also mState variable seems to have being destroyed prior to execute "return null;" statement.

String mState = null;
for (PacketExtension ext : packetExtensions) {
    if (elementName.equals(ext.getElementName()) && namespace.equals(ext.getNamespace()))
    {
        mState = "found";
        return ext;
     }
}
return null;

I have also try to recode as below, but also face with the same problem as before.

PacketExtension ext = null;
for (Iterator<PacketExtension> iterator = packetExtensions.iterator(); iterator.hasNext(); ) {
    ext = iterator.next();
    if (elementName.equals(ext.getElementName()) && namespace.equals(ext.getNamespace())
    {
        return ext;
    }
]
return null;

The below modified code is not working either. Even if I tried to assign ext to new local variable ext2 when "if statement" is true; and change "return null;" to "return ext2;", ext2 is also get destroyed before its "return ext2" and new approach is also not working. Appreciate some expert advice.

PacketExtension ext = null;
PacketExtension ext2 = null;

for (Iterator<PacketExtension> iterator = packetExtensions.iterator(); iterator.hasNext(); ) {
    ext = iterator.next();
    if (elementName.equals(ext.getElementName()) && namespace.equals(ext.getNamespace())
    {
        ext2 = ext;
        break;
    }
]
return ext2;

Answer 1

If by "the next statement "return ext;" is not being executed." you mean that when stepping with the debugger the "current statement" indicator goes to the second return, it's just an issue with Android debugging with Eclipse.

Whenever there is more than an exit point in a method, it will be shown on the last one. However, the result is correct, you can check that by stepping out to the caller method and verifying the returned value.

Answer 2

String mState = null;
PacketExtension ext = null;

for (PacketExtension ext : packetExtensions) {
    if (elementName.equals(ext.getElementName()) && namespace.equals(ext.getNamespace()))
    {
        mState = "found";
         this.ext = ext;
        break;
    }
}
return ext;