Control flow

You could say that control flow is the bread and butter of program writing. We will begin by exploring two conditional expressions: if and when.

The if expression

In Java, the if statement is not an expression and does not return a value. Let’s examine the following function, which returns one of two possible values:

public String getUnixSocketPolling(boolean isBsd) {
    if (isBsd) {
        return "kqueue";
    } else {
        return "epoll";
    }
}

While this example is easy to understand, it is generally discouraged to have multiple return statements, as it can make code more difficult to comprehend.

We can rewrite this method using Java’s var keyword:

public String getUnixSocketPolling(boolean isBsd) {
    var pollingType = "epoll";
    if (isBsd) {
        pollingType = "kqueue";
    }
    return pollingType;
}

In our previous example, we used a single return statement but had...