Overloading与Overriding的概念
一、 Overloading
在一个类的内部,方法名相同,参数列表不同(类型,顺序,个数)的方法,返回值不要求,这种情况叫重载。编译器选择使用的方法,所以重载又被称之为编译时多态,对使用者屏蔽因为参数不同所造成的方法间的差异。
找方法时如果没有合适的,采取自动向上扩展原则,如“代码1”:
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public class TestOverLoading{
public static void main(String[] args){
Student s=new Student();
s.print(3);
}
}
class Student{
public void print(short num){
System.out.println(num);
}
public void print(double num){
System.out.println(num);
}
}
public class TestOverLoading{
public static void main(String[] args){
Student s=new Student();
s.print(3);
}
}
class Student{
public void print(short num){
System.out.println(num);
}
public void print(double num){
System.out.println(num);
}
}
代码1
此时s.print(3)没有找到相应的print(int num)的方法,这时它会自动向上扩展,找到println(double num)。
尽管如此,对方法的调用一定要明确,如“代码2”:
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public class TestOverLoading{
public static void main(String[] args){
Student s=new Student();
char a = '中';
char b = '国';
s.print(a,b);
}
}
class Student{
public void print(byte b,short c){
System.out.println(b + c);
}
public void print(short c,byte b){
System.out.println(c + b);
}
}
public class TestOverLoading{
public static void main(String[] args){
Student s=new Student();
char a = '中';
char b = '国';
s.print(a,b);
}
}