Question

如何实例化Java内部类

/**
* @author 2011301510060
*
*/
import java.util.Scanner;
public class People
{
private String szName;
private String szSex;
private int age;
private int height;
private int weight;
static int sum = 0;

public People(){}

public People(String _name, String _sex, int _age, int _height, int _weight)
{
this.szName = _name;
this.szSex = _sex;
this.age = _age;
this.height = _height;
this.weight = _weight;
}

public static void setSum(int _sum) {
sum = _sum ;
System.out.println("sum = "+sum);
}

public void setName(String _name) {
szName = _name;
}

public String getName() {
return this.szName;
}

public void setSex(String _sex) {
szSex = _sex;
}

public String getSex() {
return this.szSex;
}

public void setAge(int _age) {
age = _age;
}

public int getAge() {
return this.age;
}

public void setHeight(int _height) {
height = _height;
}

public int getHeight() {
return this.height;
}

public void setWeight(int _weight) {
weight = _weight;
}

public int getWeight() {
return this.weight;
}
class Hobby
{
public void showAllinformation(People one) {
System.out.println("sum = "+sum);
System.out.println("name:"+one.getName());
System.out.println("sex:"+one.getSex());
}
public Hobby()
{
System.out.println("i am a inner class!");
}
}

}

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);
People me = new People();

People one = new People();
People.Hobby hobby = one.new Hobby(); ///////////////////////// 这里报错

}

}

Answer 1

假设外部类叫Out，内部类叫In，那么我们可以使用Out.In in = new Out().new In()来实例化内部类的对象，具体示例代码如下：

class Out {
private int age = 12;

class In {
private int age = 13;
public void print() {
int age = 14;
System.out.println("局部变量：" + age);
System.out.println("内部类变量：" + this.age);
System.out.println("外部类变量：" + Out.this.age);
}
}
}

public class Demo {
public static void main(String[] args) {
Out.In in = new Out().new In();
in.print();
}
}

Answer 2

内部类的实例化方式如下例子所示：
public class Animal {
class Head{
}
}
测试如何实例化内部类：
public class TestInstanceInnerClass {
public TestInstanceInnerClass() {
Animal animal=new Animal();//首先实例化外部类
Head head=animal.new Head();//把内部类当成一个成员变量进行实例化
}
}

Answer 3

把Hobby类提取出来，当作一个类，在People类的属性中添加一个Hobby类的对象

追问

我想像上面那样实例化。其他的方法暂且不考虑。thanks

Answer 4

怎么会报错呢？

下面这2种都可以：

People one = new People();

  People.Hobby hobby = one.new Hobby();

  Hobby bby = one.new Hobby();

Answer 5

People p = new People();
Hobby h = p.new Hobby();

追问

貌似 不行啊

追答

你的代码里面多写了一个  } 号
__________________________________
public Hobby()
{
System.out.println("i am a inner class!");
}
}

}------>这里

追问

http://yun.baidu.com/share/link?shareid=3384082929&uk=3910849304

代码在上面，要不你试试把hobby的定义体放在public void displayInformation();函数的下面试试？