Guava optional of String or with prefix

Question

I have the following example code

public String getAliasSQL() {
    StringBuilder builder = new StringBuilder();
    if (field.getAlias().isPresent()) {
        builder.append(" AS ");
        builder.append(field.getAlias().get());
    }
    return builder.toString();
}

@Override
public Optional<String> getAlias() {
    return field.getAlias();
}

And I am wondering if it is possible to do this with a one line statement using the guava or() method or another simple trick.

Something like

public String getAliasSQL() {
    return field.getAlias().or("").prefixIfNotEmpty(" AS ");
}

But in a more readable way so it still would be clean code.

Answer 1

field.getAlias().transform(new Function(String, String) {
    @Override
    public String apply(String alias) {
        return " AS " + alias;
    }
}).or(""); 

This is verbose of course, but that is caused by the lack of lambda before Java 8. With Java 8, it becomes

field.getAlias().transform(alias -> " AS " + alias).or("");