The difference between a reference to Java and a pointer to C

Believe that most beginners of Java will have doubts, what is the difference between reference and pointer?

Let's take a look at the Exchange function in the C language

1#include"stdio.h"2 voidSwapint*a,int*b)3 {4     inttemp=*A;5*a=*b;6*b=temp;7 }8 Main ()9 {Ten     intA=1, b=2; OneSwap (&a,&b); Aprintf"%d%d", A, b); -}

It's simple, just pass an address with your pointer, but what about a pointer in Java?

You can only create object implementations or use arrays without pointers.

1  Public classSwaptest {2     3      Public intA;4      Public intb;5 6      Public Static voidMain (string[] args) {7         8Swaptest s =Newswaptest ();9S.a=1;Tens.b=2; One Change (s); ASystem.out.println (s.a+ "" +s.b); -     } -      Public Static voidChange (Swaptest i) { the         inttemp=I.A; -I.a=I.B; -i.b=temp; -     } +}

See here maybe someone would say that an Integer is also a reference type why can't we just use it to pass it? We can look at it.

1  Public classSwaptest {2     3 4      Public Static voidMain (string[] args) {5         6 7Integer a=1,b=2;8 Change (A, b);9System.out.println (+ "+" +b);Ten     } One      Public Static voidChange (Integer A,integer b) { AInteger temp=A; -A=b; -b=temp; the     } -}

The output is still 1 2.

What is this for?

Let's look at one more example.

1  Public classSwaptest {2     3 4      Public Static voidMain (string[] args) {5         6 7Integer a=1, B;8b=A;9b=2;Ten  OneSystem.out.println (+ "+" +b); ASystem.out.println (a==b); -     } -  the}

You can guess what the output is.

The result is

0 S
False

Why?

Because integer is an immutable wrapper class

When B is assigned a value of 2, it is not to modify the value of the address referred to in B, but to create a new space to save as 2 and let B point to it

　　

So where is the reference better than the pointer?

Make the program more secure Java gives you the rules. Where can I use it?

But no pointers are so flexible.

The difference between a reference to Java and a pointer to C