In Java, override and overload are two different concepts:
- Override:
- Overriding means that a subclass redefines (overrides) a method inherited from a parent class.
- Overriding requires that the subclass method has the same method name, parameter list, and return type as the parent class method.
- Overriding can modify or extend the functionality of a parent class method, but it cannot change the signature of the method.
- Overriding can take advantage of polymorphism and call the corresponding method at runtime based on the actual type of the object.
Sample code:
class Animal {
public void makeSound() {
System.out.println("Animal makes sound");
}
}
class Dog extends Animal {
@Override
public void makeSound() {
System.out.println("Dog barks");
}
}
Animal animal = new Dog();
animal.makeSound(); // 输出："Dog barks"
- Overload:
- Overloading means that in the same class, multiple methods with the same name but different parameter lists can be defined.
- The characteristic of overloaded methods is that the number, type or order of parameters are different.
- The compiler decides which overloaded method to call based on the method's parameter list.
- Overloading can provide a more flexible way of calling methods, making it easier to handle different logical operations in different situations.
Sample code:
class Calculator {
public int add(int a, int b) {
return a + b;
}
public double add(double a, double b) {
return a + b;
}
}
Calculator calculator = new Calculator();
int result1 = calculator.add(5, 3); // 调用 int add(int a, int b)
double result2 = calculator.add(2.5, 4.7); // 调用 double add(double a, double b)
Through rewriting and overloading, code flexibility and extensibility can be achieved. 重写用于在子类中修改父类方法的行为, implement specific logic; 重载用于定义多个相似功能但参数不同的方法, provide more choices.