how to create a singleton class in java code example

Example 1: create a singleton list in java

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

Example 2: java singleton implementation

public class SingletonClass {
    private static final SingletonClass SINGLE_INSTANCE = new SingletonClass();
    private SingletonClass() {}
  public static SingletonClass getInstance() {
      return SINGLE_INSTANCE;
    }
}