Answers for "how to create a singleton class in java"

create a singleton list in java

List<String> list = Collections.singletonList("E");

java singleton example

public final class ClassSingleton {

    private static ClassSingleton INSTANCE;
    private String info = "Initial info class";
    
    private ClassSingleton() {        
    }
    
    public static ClassSingleton getInstance() {
        if(INSTANCE == null) {
            INSTANCE = new ClassSingleton();
        }
        
        return INSTANCE;
    }

    // getters and setters
}