Main.java:12: error: variable a might not have been initialized
System.out.println(a);
^
Main.java:13: error: variable b might not have been initialized
System.out.println(b);
^
Main.java:9: error: local variables referenced from a lambda expression must be final or effectively final
new Thread(()-> a = "hi").start();
^
Main.java:10: error: local variables referenced from a lambda expression must be final or effectively final
new Thread(()-> b = "hello").start();
^
4 errors