【zz】Java浅复制和深复制
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class Student implements Cloneable{ String name; int age; Student(String name,int age) { this.name=name; this.age=age; } public Object clone() { Object o=null; try { o=(Student)super.clone();//Object中的clone()识别出你要复制的是哪一个对象。 } catch(CloneNotSupportedException e) { System.out.println(e.toString()); } return o; } public static void main(String[] args) { Student s1=new Student("zhangsan",18); Student s2=(Student)s1.clone(); s2.name="lisi"; s2.age=20; System.out.println("name="+s1.name+","+"age="+s1.age);//修改学生2后，不影响学生1的值。 }}
?说明：
class Professor { String name; int age; Professor(String name,int age) { this.name=name; this.age=age; }}class Student implements Cloneable{ String name;//常量对象。 int age; Professor p;//学生1和学生2的引用值都是一样的。 Student(String name,int age,Professor p) { this.name=name; this.age=age; this.p=p; } public Object clone() { Student o=null; try { o=(Student)super.clone(); } catch(CloneNotSupportedException e) { System.out.println(e.toString()); } o.p=(Professor)p.clone(); return o; } public static void main(String[] args) { Professor p=new Professor("wangwu",50); Student s1=new Student("zhangsan",18,p); Student s2=(Student)s1.clone(); s2.p.name="lisi"; s2.p.age=30; System.out.println("name="+s1.p.name+","+"age="+s1.p.age);//学生1的教授成为lisi,age为30。 }}
?那应该如何实现深层次的克隆，即修改s2的教授不会影响s1的教授？代码改进如下。
class Professor implements Cloneable{ String name; int age; Professor(String name,int age) { this.name=name; this.age=age; } public Object clone() { Object o=null; try { o=super.clone(); } catch(CloneNotSupportedException e) { System.out.println(e.toString()); } return o; }}class Student implements Cloneable{ String name; int age; Professor p; Student(String name,int age,Professor p) { this.name=name; this.age=age; this.p=p; } public Object clone() { Student o=null; try { o=(Student)super.clone(); } catch(CloneNotSupportedException e) { System.out.println(e.toString()); } o.p=(Professor)p.clone(); return o; } public static void main(String[] args) { Professor p=new Professor("wangwu",50); Student s1=new Student("zhangsan",18,p); Student s2=(Student)s1.clone(); s2.p.name="lisi"; s2.p.age=30; System.out.println("name="+s1.p.name+","+"age="+s1.p.age);//学生1的教授不改变。 }}
?3．利用串行化来做深复制
public Object deepClone(){ //将对象写到流里 ByteArrayOutoutStream bo=new ByteArrayOutputStream(); ObjectOutputStream oo=new ObjectOutputStream(bo); oo.writeObject(this); //从流里读出来 ByteArrayInputStream bi=new ByteArrayInputStream(bo.toByteArray()); ObjectInputStream oi=new ObjectInputStream(bi); return(oi.readObject());}
class Professor implements Serializable{ String name; int age; Professor(String name,int age) { this.name=name; this.age=age; }}class Student implements Serializable{ String name;//常量对象。 int age; Professor p;//学生1和学生2的引用值都是一样的。 Student(String name,int age,Professor p) { this.name=name; this.age=age; this.p=p; } public Object deepClone() throws IOException,OptionalDataException,ClassNotFoundException { //将对象写到流里 ByteArrayOutoutStream bo=new ByteArrayOutputStream(); ObjectOutputStream oo=new ObjectOutputStream(bo); oo.writeObject(this); //从流里读出来 ByteArrayInputStream bi=new ByteArrayInputStream(bo.toByteArray()); ObjectInputStream oi=new ObjectInputStream(bi); return(oi.readObject()); } public static void main(String[] args) { Professor p=new Professor("wangwu",50); Student s1=new Student("zhangsan",18,p); Student s2=(Student)s1.deepClone(); s2.p.name="lisi"; s2.p.age=30; System.out.println("name="+s1.p.name+","+"age="+s1.p.age); //学生1的教授不改变。 }}
