Complex initialization in Java

Complex initialization in Java

Although boring, it is still listed.

6.1 Memento1 code in memorandum mode (5.6)

Routines 7-2 unchanged class package intent. memento; public final class Memento1 {private final VirtualState state State; // the state to be remembered, public Memento1 (state State state) {this. state = new VirtualState (state);} State getState () {State state State = new state (this. state. x, this. state. y); return state;}/*** deep cloning technology can be used. */Class VirtualState {private int x; private int y; public VirtualState (State state) {x = state. getX (); y = State. getY ();}}}

In the program VirtualStateIt is intended to remind programmers that the saved state is not the same object as the Originator Member state.

In fact, yqj2065 will never design a redundant class drop, or use State.

Therefore, the corresponding code is available:

Package intent. memento; public final class Memento2 {private final State state State; // the state to be remembered, public Memento2 (State state State) {this. state = new State () {setX (state. getX (); setY (state. getY () ;}};} State getState () {return new State () {setX (state. getX (); setY (state. getY ());}};}}

A boring thing here

new State(){{setX(state.getX());setY(state.getY());}};

In Introduction to programming (Java) p80, we also mentioned {{;}};
Class external initialization block.