11 A B

package cn.lyhh;
class Person{
    private String name;
    private int age;
    static String city =  "A城";
    public Person(String name,int age) {
        this.name = name;
        this.age = age;
    }
    public String getInfo() {
        return "姓名:" + this.name + ",年龄:" + this.age + ",城市:" + city;
    }
}
public class L {
    public static void main(String[] args) {
        Person per1 = new Person("张三",30);
        Person per2 = new Person("李四",31);
        Person per3 = new Person("王五",30);
        System.out.println("======修改信息之前======");
        System.out.println(per1.getInfo());
        System.out.println(per2.getInfo());
        System.out.println(per3.getInfo());
        System.out.println("======修改信息之后======");
        Person.city = "B城";
        System.out.println(per1.getInfo());
        System.out.println(per2.getInfo());
        System.out.println(per3.getInfo());
        
    }

}

package cn.lyhh;
class La{
    private static La instance = new La();
    private La() {
    }
    public static La getInstance() {
        return instance;
    }
    public void print() {
        System.out.println("hello world!!!");
    }
}
public class L {
    public static void main(String[] args) {
        La s = null;
        s = La.getInstance();
        s.print();
    }

}

package cn.lyhh;
class La{
    private static La instance = new La();
    private La() {
    }
    public static La getInstance() {
        return instance;
    }
    public void print() {
        System.out.println("hello world!!!");
    }
}
public class L {
    public static void main(String[] args) {
        La s = null;
        s = La.getInstance();
        s.print();
    }

}

package cn.lyh;
class Person{
    private String name;
    private static int count;
    public Person() {
        count++;
        this.name = "NONAME - " + count;
    }
    public Person(String name) {
        this.name = name;
    }
    public String getInfo() {
        return "姓名:" + this.name;
    }
}
public class Ly{
    public static void main(String[] args) {
        System.out.println(new Person().getInfo());
        System.out.println(new Person("A").getInfo());
        System.out.println(new Person("B").getInfo());
        System.out.println(new Person().getInfo());
    }

}

package cn.lyh;
class Person{
    private String name;
    private static int count;
    public Person() {
        count++;
        System.out.println("产生了" + count + "个实例化");
    }
    public String getInfo() {
        return "姓名:" + this.name;
    }
}
public class Y {
    public static void main(String[] args) {
        new Person();
        new Person();
        new Person();
        new Person();
        new Person();
    }
}