相關(guān)要點(diǎn):
1.必須實(shí)現Cloneable接口，這個(gè)接口只是一個(gè)標識；如果不實(shí)現，調用了clone()，運行時(shí)會(huì )報CloneNotSupportedException
2.clone是Object的方法，標識為protected，子類(lèi)必須重寫(xiě)，標識符可改為public
3.對于jdk1.5,clone可以返回相應類(lèi)的類(lèi)型或Object；對于1.4，只能返回Object
4.注意深復制和淺復制
淺復制
(1)對于int,double,Double,String等基本類(lèi)型，super.clone()是采用的深復制
view plaincopy to clipboardprint?public class TestShallow implements Cloneable {
public int a;
public String b;
public Double c;
public TestShallow clone() throws CloneNotSupportedException{
return (TestShallow)super.clone();
}
}
class Test {
public static void main(String[] args) throws CloneNotSupportedException {
TestShallow a = new TestShallow();
a.a = 12;
a.b = "hahaa";
a.c = 14.11;
System.out.println("a原值");
print(a);
TestShallow b = a.clone();
b.a = 13;
b.b = "hahab";
b.c = 15.11;
System.out.println("a現值");
print(a);
System.out.println("b現值");
print(b);
}
public static void print(TestShallow a) {
System.out.println("a=" + a.a);
System.out.println("b=" + a.b);
System.out.println("c=" + a.c);
}
}
結果:
a原值
a=12
b=hahaa
c=14.11
a現值
a=12
b=hahaa
c=14.11
b現值
a=13
b=hahab
c=15.11
(2)對其他類(lèi)及自定義類(lèi)，默認采用的是淺復制
view plaincopy to clipboardprint?class A {
public String a;
}
public class TestShallow1 implements Cloneable {
public int a;
public A b;
public TestShallow1() {
b = new A();
}
public TestShallow1 clone() throws CloneNotSupportedException{
return (TestShallow1)super.clone();
}
}
class Test1 {
public static void main(String[] args) throws CloneNotSupportedException {
TestShallow1 a = new TestShallow1();
a.a = 12;
a.b.a = "hahaa";
System.out.println("a原值");
print(a);
TestShallow1 b = a.clone();
b.a = 13;
b.b.a = "hahab";
System.out.println("a現值");
print(a);
System.out.println("b現值");
print(b);
}
public static void print(TestShallow1 a) {
System.out.println("a=" + a.a);
System.out.println("b=" + a.b.a);
}
}
結果：
a原值
a=12
b=hahaa
a現值
a=12
b=hahab
b現值
a=13
b=hahab
深復制
對于其中非基本類(lèi)型的字段，必須明確進(jìn)行其賦值
view plaincopy to clipboardprint?class A implements Cloneable {
public String a;
public A clone() throws CloneNotSupportedException{
return (A)super.clone();
}
}
public class TestDeep implements Cloneable {
public int a;
public A b;
public TestDeep() {
b = new A();
}
public TestDeep clone() throws CloneNotSupportedException{
TestDeep clone = (TestDeep)super.clone();
clone.b = this.b.clone();
return clone;
}
}
class Test1 {
public static void main(String[] args) throws CloneNotSupportedException {
TestDeep a = new TestDeep();
a.a = 12;
a.b.a = "hahaa";
System.out.println("a原值");
print(a);
TestDeep b = a.clone();
b.a = 13;
b.b.a = "hahab";
System.out.println("a現值");
print(a);
System.out.println("b現值");
print(b);
}
public static void print(TestDeep a) {
System.out.println("a=" + a.a);
System.out.println("b=" + a.b.a);
}
}
結果:
a原值
a=12
b=hahaa
a現值
a=12
b=hahaa
b現值
a=13
b=hahab
