How to do the opposite of StringBuilder append in Java?

Question

What would be the opposite of:

savedPlanets.append(planet.getDisplayName()+\",\");

I have a list and I am adding the name of the planet every t

Answer 1

You can do following:

 savedPlanets.replace(planet.getDisplayName(),"");

Ideally I would do a solution like following:

Set selectedPlanets = new HashSet();

selectedPlanets.add(planet.getDisplayName());        // Whenever a planet is selected
selectedPlanets.remove(planet.getDisplayName());     // Whenever a planet is removed 

// Prepare a String with all planets        
StringBuilder savedPlanets = new StringBuilder("");
for(String planetName : selectedPlanets ){
    savedPlanets.append(planetName).append(",");
}
// Removing , from the end if any       
if(savedPlanets.toString().endsWith(","))
    finalValue = savedPlanets.substring(0, savedPlanets.length()-1);

// finalValue is what you are looking for