记忆之前的操作状态，必要时恢复；
游戏：
<pre>
public class Game {
private static final String TAG = "Game";
private int order;
private int surplusNum;
public Game() {
}
public Game(int order, int surplusNum) {
Log.i(TAG, "playGame: 关卡=" + order + "剩余游戏次数=" + surplusNum);
this.order = order;
this.surplusNum = surplusNum;
}
public Memory saveState() {
Memory memory = new Memory();
memory.order = order;
memory.surplusNum = surplusNum;
return memory;
}
public void recover(Memory memory) {
order = memory.order;
surplusNum = memory.surplusNum;
}
public void playGame() {
Log.i(TAG, "playGame: 关卡=" + ++order + "剩余游戏次数=" + --surplusNum);
}
public Memory quit() {
Memory memory = saveState();
Log.i(TAG, "quit: " + memory.toString());
return memory;
}
}
</pre>
记忆：
<pre>
public class Memory {
int order;
int surplusNum;
@Override
public String toString() {
final StringBuilder sb = new StringBuilder("Memory{");
sb.append("order=").append(order);
sb.append(", surplusNum=").append(surplusNum);
sb.append('}');
return sb.toString();
}
}
</pre>
存储记忆：
<pre>
public class Caretaker {
Memory memory;
public Memory getMemory() {
return memory;
}
public void setMemory(Memory memory) {
this.memory = memory;
}
}
</pre>
使用：
<pre>
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Game game = new Game(1, 10);
game.playGame();
game.playGame();
Memory memory = game.quit();
Caretaker caretaker = new Caretaker();
caretaker.setMemory(memory);
Game game2 = new Game();
game2.recover(caretaker.getMemory());
game2.playGame();
}
}
</pre>
log：
<pre>
03-10 21:25:34.223 5445-5445/com.lerz.memorydemo I/Game: playGame: 关卡=1剩余游戏次数=10
03-10 21:25:34.223 5445-5445/com.lerz.memorydemo I/Game: playGame: 关卡=2剩余游戏次数=9
03-10 21:25:34.223 5445-5445/com.lerz.memorydemo I/Game: playGame: 关卡=3剩余游戏次数=8
03-10 21:25:34.223 5445-5445/com.lerz.memorydemo I/Game: quit: Memory{order=3, surplusNum=8}
03-10 21:25:34.223 5445-5445/com.lerz.memorydemo I/Game: playGame: 关卡=4剩余游戏次数=7
</pre>
