Creating a 4 digit Random Number using java with no repetition in digits

Creating a 4 digit Random Number using java with no repetition in digits

I wrote a code using java to create a random 4 digit number with no
repetition of digits, the code I wrote is given below :-

Random r = new Random();
d1 = r.nextInt(9);
d2 = r.nextInt(9);
d3 = r.nextInt(9);
d4 = r.nextInt(9);
while(d1==d2||d1==d3||d1==d4||d2==d3||d2==d4||d3==d4)
{
if(d1==d2||d2==d3||d2==d4)
{
d2 = r.nextInt(9);
}
if(d1==d3||d2==d3||d3==d4)
{
d3 = r.nextInt(9);
}
if(d1==d4||d2==d4||d3==d4)
{
d4 = r.nextInt(9);
}
}
System.out.println(d1+""+d2+""+d3+""+d4);

here are the test cases(generated from
System.out.println(R1+""+R2+""+R3+""+R4);) are as following :-

0123 | OK as required
1234 | OK as required
2123 | not OK because 2 is present more than one time
9870 | OK as required
0444 | not OK because 4 is present more than one time

Now My question here is, that if there is some better way to do this. If I
could enhance it in some way?