Java programming ideology _ 005 alias Phenomenon

Package WZS. test2; // assign an object to another object. Actually, the reference is copied from one place to another. // This means that if the object tank1 = tank2, so both tank1 and tank2 point to the object that originally only tank2 points to // to avoid this problem, tank1.level = tank2.levelpublic class test_wzs2 {public static void main (string [] ARGs) {tank tank1 = new tank (); tank tank2 = new tank (); tank1.level = 1; tank2.level = 2; system. out. println ("tank1.level =" + tank1.level + ", tank2.level =" + tank2.level); tank1 = tank2; system. out. println ("tank1.level =" + tank1.level + ", tank2.level =" + tank2.level); tank1.level = 5; system. out. println ("tank1.level =" + tank1.level + ", tank2.level =" + tank2.level); tank2.level = 7; system. out. println ("tank1.level =" + tank1.level + ", tank2.level =" + tank2.level); // ------------------------ tank tank3 = new tank (); tank tank4 = new tank (); tank3.level = 1; tank4.level = 2; tank3.level = tank4.level; system. out. println ("\ ntank3.level =" + tank3.level + ", tank4.level =" + tank4.level); tank3.level = 7; tank4.level = 8; system. out. println ("tank3.level =" + tank3.level + ", tank4.level =" + tank4.level) ;}} class tank {int level ;}

Output result:

tank1.level=1, tank2.level=2tank1.level=2, tank2.level=2tank1.level=5, tank2.level=5tank1.level=7, tank2.level=7tank3.level=2, tank4.level=2tank3.level=7, tank4.level=8