NoSuchMethodError 错误

[mxk0921]

用序列化方法写深克隆时出现这个错误。求高手解答

Exception in thread "main" java.lang.NoSuchMethodError: Country.setP(LPopulation;)V
at Client2_3.main(Client2_3.java:14)

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;


public class Client2_3 {
	public static void main(String[] args) {
		Country america = new Country();
		Population p1 = new Population();
		p1.setPpl(10000);
		america.setP(p1);
		int america_ppl = america.getP().getPpl();
		
		Country china = (Country) Country.deepClone(new Country());
		china.getP().setPpl(20000);
		int china_ppl = china.getP().getPpl();
		
		System.out.println("the population of America is "+america_ppl);
		System.out.println("the population of China is "+china_ppl);
	}

}

class Population implements Serializable {
	private int ppl;

	public int getPpl() {
		return ppl;
	}

	public void setPpl(int ppl) {
		this.ppl = ppl;
	}
	
}

class Country implements Serializable{
    private Population p;
    
    public Population getP() {
        return p;
    }
    public void setP(Population p) {
        this.p = p;
    }
    public static Object deepClone(Object src) {
        Object dst = null;
        try {
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            ObjectOutputStream oo = new ObjectOutputStream(out);
            oo.writeObject(src);

            ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
            ObjectInputStream oi = new ObjectInputStream(in);
            dst = oi.readObject();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }       
        return dst;
    }
}

[qqhw123]

Country china = (Country) Country.deepClone(new Country());
china.getP().setPpl(20000);
这里有问题，你应该把america放进去，而不是new Country()
不然的话，会报NullPointerException

至于你提示的错误，我运行的时候没有出现。

[菖蒲老先生]

Country china = (Country) Country.deepClone(america);
没你说的那个错。。。

[mxk0921]

谢谢你们的回答。不过我试了还是不行。。

[mxk0921]

我放到另外一个包就没报错。。真TM神奇

[菖蒲老先生]

哪里不行了，我的运行出结果了。

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class Client2_3 {
	public static void main(String[] args) {
		Country america = new Country();
		Population p1 = new Population();
		p1.setPpl(10000);
		america.setP(p1);
		int america_ppl = america.getP().getPpl();

		Country china = (Country) Country.deepClone(america);
		china.getP().setPpl(20000);
		int china_ppl = china.getP().getPpl();

		System.out.println("the population of America is " + america_ppl);
		System.out.println("the population of China is " + china_ppl);
	}

}

class Population implements Serializable {
	private int ppl;

	public int getPpl() {
		return ppl;
	}

	public void setPpl(int ppl) {
		this.ppl = ppl;
	}

}

class Country implements Serializable {
	private Population p;

	public Population getP() {
		return p;
	}

	public void setP(Population p) {
		this.p = p;
	}

	public static Object deepClone(Object src) {
		Object dst = null;
		try {
			ByteArrayOutputStream out = new ByteArrayOutputStream();
			ObjectOutputStream oo = new ObjectOutputStream(out);
			oo.writeObject(src);

			ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
			ObjectInputStream oi = new ObjectInputStream(in);
			dst = oi.readObject();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		return dst;
	}
}

// 运行结果
// the population of America is 10000
// the population of China is 20000

[Quote=引用 3 楼 的回复:]

谢谢你们的回答。不过我试了还是不行。。
[/Quote]