摘要： public class Memory { private static Memory instance = new Memory(); public static Memory getInstance() { return instance; } public boolean check(bool 阅读全文

摘要： import java.util.Stack; public abstract class AbstractCommand { public abstract int execute(int value); public abstract int undo(); public abstract in 阅读全文

摘要： public class Student{ private String id; private String name; private String age; public String getAge() { return age; } public void setAge(String age 阅读全文