What happens when you set two references to the same object equal to each other?-CodePudding

For example, let's say we have a code snippet as follows:

Rectangle r1 = new Rectangle( 5 );
Rectangle r2 = new Rectangle( 10 );
Rectangle r3 = r1;

r1.length = 30;
r1 = r2;
r2 = r3;
r1 = r2;

What exactly is happening when we set r1 to r2 and r2 to r3? Does everything that happens to r2 then happen to r1, etc.?

CodePudding user response：

Rectangle r1 = new Rectangle( 5 ); // A
Rectangle r2 = new Rectangle( 10 ); // B
Rectangle r3 = r1; // r3 = A

r1.length = 30; // Mutate A
r1 = r2; // r1 = B
r2 = r3; // r2 = A
r1 = r2; // r1 = A

Reassigning a variable with will just change the value to which that variable points to.

In the end we can see all 3 variables will point to A and B reference will be lost.

CodePudding user response：

At first:

End: (The rectangle object below will be recycled by the GC because there is no reference to it)

What you did was a reference change, r1, r2 were pointed to different objects.