#final in java is a keyword that can be used to modify references, methods and classes. (Recommended: java video tutorial)
1. Used to modify a reference
If the reference is a basic data type, the reference is a constant, and the value Cannot be modified;
If the reference is a reference data type, such as an object or array, the object or array itself can be modified, but the reference pointing to the address of the object or array cannot be modified.
If the reference is to a member variable of the class, it must be assigned a value on the spot, otherwise the compilation will report an error.
An example is as follows:
final class Person {
String name ="zs";
//3. 此處不賦值會(huì)報(bào)錯(cuò)
//final int age;
final int age = 10;
}
public class Demo01 {
public static void main(String[] args) {
//1. 基本數(shù)組類型為常量，無(wú)法修改
final int i = 9;
//i = 10;
//2. 地址不能修改，但是對(duì)象本身的屬性可以修改
Person p = new Person();
p.name = "lisi";
final int[] arr = {1,2,3,45};
arr[3] = 999;
//arr = new int[]{1,4,56,78};
}
}2. Used to modify a method
When a final modified method is used, this method will become the final method and cannot be overridden by subclasses . However, the method can still be inherited.
class Person {
public final void say() {
System.out.println("說(shuō)....");
}
public void eat() {
System.out.println("吃...");
}
}
class Teacher extends Person {
//1. final修飾的方法不能被重寫，但此方法仍然被繼承
/*@Override
public void say() {
System.out.println("老師在一本正經(jīng)的說(shuō)...");
}*/
public void eat() {
System.out.println("老師在大口大口的吃...");
}
}
public class Demo02 {
public static void main(String[] args) {
Teacher t = new Teacher();
t.say();
}
}3. Used to modify the class
When using final to modify a class, the class becomes the final class and cannot be inherited. It is simply called "cutting off descendants and exterminating the descendants".
/***
* final用法3：修飾類，則該類成為最終類，無(wú)法被繼承
* @author Administrator
*
*/
final class Person02 { }
//class Teacher02 extends Person02 { }
//class MyString extends String{}
public class Demo03 {
}For more java knowledge, please pay attention to the java basic tutorial column.
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