Errata

The code for A and B each feature a line that includes a semicolon. These semicolons are redundant, and should be removed. The line:
var x = 0;
should be:
var x = 0
and the line:
var firemanNo = 0;
should be:
var firemanNo = 0

Original: "You can pass variables to a function so long as the variable type matches the parameter type"

Readers might get the impression that *only* variables can be passed to a function. This could be misleading. "argument" is a more general term that also includes "plain" values.

Suggestion: Use "arguments/type of argument“ instead of "variable".

Note from the Author or Editor:
Change the third heading to:
You can pass arguments to a function so long as the argument type matches the parameter type

Heading reads "More powerful boolean expressions (continued)", but there is no previous heading of that name.

Suggested fix: Remove "(continued)"

Note from the Author or Editor:
We don't need the main heading on this page, as it's really a continuation of the previous page. The entire heading "More powerful boolean expressions (continued)" can be removed.

Original: "Creates a Duck variable, and assigns it a reference to a Duck object."

Should be "Creates a myDuck variable, and assigns it a reference to a Duck object." to match the code example on the left.

Suggested fix: change "Duck variable" to "myDuck variable"

Note from the Author or Editor:
For extra clarification, the last but one annotation on page 109 can be changed to: Creates a Duck variable named myDuck, and assigns it a reference to a Duck object.

Location:
"The following code, for example, checks that w’s value is not null, and then calls the object’s eat function:"

Problem:
Missing parentheses for 'eat()' function in text.

Suggested fix:
Add parentheses after 'eat' for consistency and to avoid confusion.

"If w and hunger are is not null," should read, "If w and hunger are not null."

Hi! On page 259 there is an example that says:
"The following code, for example, copies mShopping, and assigns the copy to a new variable named shoppingSnapshot"

The Variable called shoppingSnapshot is wrong because the following example is:

val shoppingCopy = mShopping.toList()

So the variable should be called shoppingCopy instead shoppingSnapshot.

Note from the Author or Editor:
shoppingSnapshot in the body text needs to be changed to shoppingCopy.

Text:
"The following things happen when you call the convert function using the code:"

Missing formatting for "convert"

Suggested fix:
Format "convert" as code.

The option name has changed slightly. It is now "Kotlin/JVM".
Also, by default, the option "Java" is selected. This should be deselected.

Note from the Author or Editor:
Update the text to say "To do this, create a new project, select the Gradle option, check the Kotlin (Java) option, and make sure all the other options for additional libraries and frameworks are unchecked."

Original: "To do this, open build.gradle, and update the dependencies section like so:"

Problem: Files in IDEA are usually open by simply clicking on them (contents is then shown in main window). build.gradle needs to be double clicked to show its contents.

Suggestion: Update text to say: "To do this, open build.gradle with a double click on the file name, and update the dependencies section like so:"

System: macOS 10.12.6 (Sierra), IntelliJ IDEA 2019.1