Explain why constructor inject is better than other options [duplicate]

Answer 1

With examples? Here's a simple one:

public class TwoInjectionStyles {
    private Foo foo;

    // Constructor injection
    public TwoInjectionStyles(Foo f) {
        this.foo = f;
    }

    // Setting injection
    public void setFoo(Foo f) { this.foo = f; }
}

Personally, I prefer constructor injection when I can.

In both cases, the bean factory instantiates the TwoInjectionStyles and Foo instances and gives the former its Foo dependency.