How do the instance variables effect the values of my constructors here?
I am working through a java exercise and am somewhat confused what the new values of the last 4 lines of code are.
public class Snake
public Snake x = null;
public Snake y = null;
public static void main(String args)
Snake a = new Snake();
Snake b = new Snake();
a.x = a;
b.x = a.x;
b.y = b.x;
a.y = b.y.x;
java variables constructor
edited Nov 13 '18 at 17:09
Michael
19.6k83470
asked Nov 13 '18 at 17:05
Salizmo SqueegeeSalizmo Squeegee
22
add a comment |
I am working through a java exercise and am somewhat confused what the new values of the last 4 lines of code are.
public class Snake
public Snake x = null;
public Snake y = null;
public static void main(String args)
Snake a = new Snake();
Snake b = new Snake();
a.x = a;
b.x = a.x;
b.y = b.x;
a.y = b.y.x;
java variables constructor
edited Nov 13 '18 at 17:09
Michael
19.6k83470
asked Nov 13 '18 at 17:05
Salizmo SqueegeeSalizmo Squeegee
22
You just have an object with a property that points to the object itself... and that's a little like the beginning of infinity :-)
– ernest_k
Nov 13 '18 at 17:09
By the end both X and Y fields of A and B are equal to A. Whoever authored this exercise is an idiot. It's like trying to teach someone English with "how much wood would a woodchuck chuck"
– Michael
Nov 13 '18 at 17:12
add a comment |
I am working through a java exercise and am somewhat confused what the new values of the last 4 lines of code are.
public class Snake
public Snake x = null;
public Snake y = null;
public static void main(String args)
Snake a = new Snake();
Snake b = new Snake();
a.x = a;
b.x = a.x;
b.y = b.x;
a.y = b.y.x;
java variables constructor
edited Nov 13 '18 at 17:09
Michael
19.6k83470
asked Nov 13 '18 at 17:05
Salizmo SqueegeeSalizmo Squeegee
22
I am working through a java exercise and am somewhat confused what the new values of the last 4 lines of code are.
public class Snake
public Snake x = null;
public Snake y = null;
public static void main(String args)
Snake a = new Snake();
Snake b = new Snake();
a.x = a;
b.x = a.x;
b.y = b.x;
a.y = b.y.x;
java variables constructor
java variables constructor
edited Nov 13 '18 at 17:09
Michael
19.6k83470
asked Nov 13 '18 at 17:05
Salizmo SqueegeeSalizmo Squeegee
22
edited Nov 13 '18 at 17:09
Michael
19.6k83470
asked Nov 13 '18 at 17:05
Salizmo SqueegeeSalizmo Squeegee
22
edited Nov 13 '18 at 17:09
Michael
19.6k83470
edited Nov 13 '18 at 17:09
Michael
19.6k83470
edited Nov 13 '18 at 17:09
Michael
19.6k83470
19.6k83470
asked Nov 13 '18 at 17:05
Salizmo SqueegeeSalizmo Squeegee
22
asked Nov 13 '18 at 17:05
Salizmo SqueegeeSalizmo Squeegee
22
asked Nov 13 '18 at 17:05
Salizmo SqueegeeSalizmo Squeegee
22
22
You just have an object with a property that points to the object itself... and that's a little like the beginning of infinity :-)
– ernest_k
Nov 13 '18 at 17:09
By the end both X and Y fields of A and B are equal to A. Whoever authored this exercise is an idiot. It's like trying to teach someone English with "how much wood would a woodchuck chuck"
– Michael
Nov 13 '18 at 17:12
add a comment |
You just have an object with a property that points to the object itself... and that's a little like the beginning of infinity :-)
– ernest_k
Nov 13 '18 at 17:09
By the end both X and Y fields of A and B are equal to A. Whoever authored this exercise is an idiot. It's like trying to teach someone English with "how much wood would a woodchuck chuck"
– Michael
Nov 13 '18 at 17:12
You just have an object with a property that points to the object itself... and that's a little like the beginning of infinity :-)
– ernest_k
Nov 13 '18 at 17:09
You just have an object with a property that points to the object itself... and that's a little like the beginning of infinity :-)
– ernest_k
Nov 13 '18 at 17:09
By the end both X and Y fields of A and B are equal to A. Whoever authored this exercise is an idiot. It's like trying to teach someone English with "how much wood would a woodchuck chuck"
– Michael
Nov 13 '18 at 17:12
By the end both X and Y fields of A and B are equal to A. Whoever authored this exercise is an idiot. It's like trying to teach someone English with "how much wood would a woodchuck chuck"
– Michael
Nov 13 '18 at 17:12
add a comment |
2 Answers
2
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oldest
votes
Then you understood that a and b are two snakes. But they are really references to two different snakes.
a.x = a : means make a.x refer to snake referred by a.
b.x = a.x : means make b.x refer to snake referred by a.x (so the same as a).
b.y = b.x : means make b.y refer to snake referred by b.x (so the same as a).
a.y = b.y.x: means make a.y refer to snake referred by b.y.x, as b.y refers to a, this refers to a.x which is the same as a.
answered Nov 13 '18 at 17:14
Jean-Baptiste YunèsJean-Baptiste Yunès
23.2k12652
add a comment |
This is how it works:
a.x = a;
the x Snake object (property) of the a Snake object becomes a reference (points) to the a Snake object itself.
b.x = a.x;
the x Snake object (property) of the b Snake object becomes a reference (points) to the a.x Snake object which previously was set to refer to the a Snake object.
So this b.x also becomes a reference (points) to the a Snake object .
b.y = b.x;
the y Snake object (property) of the b Snake object becomes a reference (points) to the b.x Snake object which previously was set to refer to the a Snake object.
So this b.y also becomes a reference (points) to the a Snake object .
a.y = b.y.x;
the y Snake object (property) of the a Snake object becomes a reference (points) to the b.y.x Snake object and since b.y was previously set to a it is equivalent to a.x which previously was set to refer to the a Snake object.
So this a.y also becomes a reference (points) to the a Snake object .
Finally: all the left parts of the assignments refer (point) to a.
answered Nov 13 '18 at 17:26
forpasforpas
11k2423
add a comment |
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2 Answers
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active
oldest
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2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Then you understood that a and b are two snakes. But they are really references to two different snakes.
a.x = a : means make a.x refer to snake referred by a.
b.x = a.x : means make b.x refer to snake referred by a.x (so the same as a).
b.y = b.x : means make b.y refer to snake referred by b.x (so the same as a).
a.y = b.y.x: means make a.y refer to snake referred by b.y.x, as b.y refers to a, this refers to a.x which is the same as a.
answered Nov 13 '18 at 17:14
Jean-Baptiste YunèsJean-Baptiste Yunès
23.2k12652
add a comment |
Then you understood that a and b are two snakes. But they are really references to two different snakes.
a.x = a : means make a.x refer to snake referred by a.
b.x = a.x : means make b.x refer to snake referred by a.x (so the same as a).
b.y = b.x : means make b.y refer to snake referred by b.x (so the same as a).
a.y = b.y.x: means make a.y refer to snake referred by b.y.x, as b.y refers to a, this refers to a.x which is the same as a.
answered Nov 13 '18 at 17:14
Jean-Baptiste YunèsJean-Baptiste Yunès
23.2k12652
add a comment |
Then you understood that a and b are two snakes. But they are really references to two different snakes.
a.x = a : means make a.x refer to snake referred by a.
b.x = a.x : means make b.x refer to snake referred by a.x (so the same as a).
b.y = b.x : means make b.y refer to snake referred by b.x (so the same as a).
a.y = b.y.x: means make a.y refer to snake referred by b.y.x, as b.y refers to a, this refers to a.x which is the same as a.
answered Nov 13 '18 at 17:14
Jean-Baptiste YunèsJean-Baptiste Yunès
23.2k12652
Then you understood that a and b are two snakes. But they are really references to two different snakes.
a.x = a : means make a.x refer to snake referred by a.
b.x = a.x : means make b.x refer to snake referred by a.x (so the same as a).
b.y = b.x : means make b.y refer to snake referred by b.x (so the same as a).
a.y = b.y.x: means make a.y refer to snake referred by b.y.x, as b.y refers to a, this refers to a.x which is the same as a.
answered Nov 13 '18 at 17:14
Jean-Baptiste YunèsJean-Baptiste Yunès
23.2k12652
answered Nov 13 '18 at 17:14
Jean-Baptiste YunèsJean-Baptiste Yunès
23.2k12652
answered Nov 13 '18 at 17:14
Jean-Baptiste YunèsJean-Baptiste Yunès
23.2k12652
answered Nov 13 '18 at 17:14
Jean-Baptiste YunèsJean-Baptiste Yunès
23.2k12652
23.2k12652
add a comment |
add a comment |
This is how it works:
a.x = a;
the x Snake object (property) of the a Snake object becomes a reference (points) to the a Snake object itself.
b.x = a.x;
the x Snake object (property) of the b Snake object becomes a reference (points) to the a.x Snake object which previously was set to refer to the a Snake object.
So this b.x also becomes a reference (points) to the a Snake object .
b.y = b.x;
the y Snake object (property) of the b Snake object becomes a reference (points) to the b.x Snake object which previously was set to refer to the a Snake object.
So this b.y also becomes a reference (points) to the a Snake object .
a.y = b.y.x;
the y Snake object (property) of the a Snake object becomes a reference (points) to the b.y.x Snake object and since b.y was previously set to a it is equivalent to a.x which previously was set to refer to the a Snake object.
So this a.y also becomes a reference (points) to the a Snake object .
Finally: all the left parts of the assignments refer (point) to a.
answered Nov 13 '18 at 17:26
forpasforpas
11k2423
add a comment |
This is how it works:
a.x = a;
the x Snake object (property) of the a Snake object becomes a reference (points) to the a Snake object itself.
b.x = a.x;
the x Snake object (property) of the b Snake object becomes a reference (points) to the a.x Snake object which previously was set to refer to the a Snake object.
So this b.x also becomes a reference (points) to the a Snake object .
b.y = b.x;
the y Snake object (property) of the b Snake object becomes a reference (points) to the b.x Snake object which previously was set to refer to the a Snake object.
So this b.y also becomes a reference (points) to the a Snake object .
a.y = b.y.x;
the y Snake object (property) of the a Snake object becomes a reference (points) to the b.y.x Snake object and since b.y was previously set to a it is equivalent to a.x which previously was set to refer to the a Snake object.
So this a.y also becomes a reference (points) to the a Snake object .
Finally: all the left parts of the assignments refer (point) to a.
answered Nov 13 '18 at 17:26
forpasforpas
11k2423
add a comment |
This is how it works:
a.x = a;
the x Snake object (property) of the a Snake object becomes a reference (points) to the a Snake object itself.
b.x = a.x;
the x Snake object (property) of the b Snake object becomes a reference (points) to the a.x Snake object which previously was set to refer to the a Snake object.
So this b.x also becomes a reference (points) to the a Snake object .
b.y = b.x;
the y Snake object (property) of the b Snake object becomes a reference (points) to the b.x Snake object which previously was set to refer to the a Snake object.
So this b.y also becomes a reference (points) to the a Snake object .
a.y = b.y.x;
the y Snake object (property) of the a Snake object becomes a reference (points) to the b.y.x Snake object and since b.y was previously set to a it is equivalent to a.x which previously was set to refer to the a Snake object.
So this a.y also becomes a reference (points) to the a Snake object .
Finally: all the left parts of the assignments refer (point) to a.
answered Nov 13 '18 at 17:26
forpasforpas
11k2423
This is how it works:
a.x = a;
the x Snake object (property) of the a Snake object becomes a reference (points) to the a Snake object itself.
b.x = a.x;
the x Snake object (property) of the b Snake object becomes a reference (points) to the a.x Snake object which previously was set to refer to the a Snake object.
So this b.x also becomes a reference (points) to the a Snake object .
b.y = b.x;
the y Snake object (property) of the b Snake object becomes a reference (points) to the b.x Snake object which previously was set to refer to the a Snake object.
So this b.y also becomes a reference (points) to the a Snake object .
a.y = b.y.x;
the y Snake object (property) of the a Snake object becomes a reference (points) to the b.y.x Snake object and since b.y was previously set to a it is equivalent to a.x which previously was set to refer to the a Snake object.
So this a.y also becomes a reference (points) to the a Snake object .
Finally: all the left parts of the assignments refer (point) to a.
answered Nov 13 '18 at 17:26
forpasforpas
11k2423
answered Nov 13 '18 at 17:26
forpasforpas
11k2423
answered Nov 13 '18 at 17:26
forpasforpas
11k2423
answered Nov 13 '18 at 17:26
forpasforpas
11k2423
11k2423
add a comment |
add a comment |
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You just have an object with a property that points to the object itself... and that's a little like the beginning of infinity :-)
– ernest_k
Nov 13 '18 at 17:09
By the end both X and Y fields of A and B are equal to A. Whoever authored this exercise is an idiot. It's like trying to teach someone English with "how much wood would a woodchuck chuck"
– Michael
Nov 13 '18 at 17:12