I am fully aware of the brace initialisation of anonymous classes, but I didn’t know that this can help to improve readability of Java programs until I read this nice post:

Map<Integer, String> map = new HashMap<Integer, String>() {{
 put(1, "one");
 put(2, "two");
 put(3, "three");
 put(4, "four");
 put(5, "five");
}};

The author said that this could help in GUI programming:

JFrame frame = new JFrame() {{
   setDefaultCloseOperation(EXIT_ON_CLOSE);  
   add(new JLabel("Hello, World!"));
   pack();
}};

Nice !