Java – spring switch implementation based on runtime conditions

This is the simplified version I want to implement

For example, suppose I am an interface called color There are many classes that implement this interface, such as red class, blue class, green class, etc

At runtime, I need to select the implementation according to user input One way to achieve this goal is this

@Autowired
 @Qualifier("Red")
 private Color redColor;

 @Autowired
 @Qualifier("Green")
 private Color greenColor;


private Color getColorImplementation()
{
if(userInput=="red")
{
return redColor;

}
else if(userInput=="green")
{
return greenColor;
}
else
{
return null;
}

}

But the problem is that every time I add a new implementation, I have to update the code of the selected implementation, which is the whole purpose of the spring control part reversal What is the correct way to do this with a spring?

Solution

You can automatically assemble all the implementations of related interfaces, and then decide to use them according to the properties provided by the interface

@Autowired
private List<Color> colors;

public void doSomething(String input) {
    colors.stream().filter(c -> c.getName().contains(input)).findFirst().ifPresent(c -> {
        // something
    }
}

This is not so magical, more in line with the OO principle Dependency injection was originally designed to connect things rather than dynamically switch at run time