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POSearch method of Stack class always returning -1
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  1. POSearch method of Stack class always returning -1
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    copied!<p>I have this class to hold two values:</p> <pre><code>public class Coord { public int x; public int y; public Coord(int x, int y) { this.x = x; this.y = y; } } </code></pre> <p>I am trying to use it in a depth-first search algorithm:</p> <pre><code>x = this.move_to_x; y = this.move_to_y; Coord stack = new Coord(0, 0); Stack&lt;Coord&gt; start = new Stack&lt;Coord&gt;(); Stack&lt;Coord&gt; visited = new Stack&lt;Coord&gt;(); start.push(stack); visited.push(stack); while (!start.empty()) { Coord tmp = (Coord)start.pop(); int j,k; j = tmp.x; k = tmp.y; // there is only 8 possible ways to go (the neighbors) for (int a = -1; a &lt; 2; a++) { tmp.x = j + a; for (int b = -1; b &lt; 2; b++) { if (a == 0 &amp;&amp; b == 0) { continue; } tmp.y = k + b; if (tmp.x &lt; 0 || tmp.y &lt; 0) { continue; } if (tmp.x &gt; 5 || tmp.y &gt; 5) { continue; } if (tmp.x == x &amp;&amp; tmp.y == y) { System.out.println("end!"); return; } Coord push = new Coord(tmp.x, tmp.y); System.out.println("visited: " + visited); if (visited.search(push) == -1) { System.out.println("added x " + push.x + " y " + push.y + " " + visited.search(push)); start.push(push); visited.push(push); } else { System.out.println("visited x " + tmp.x + " y " + tmp.y + " index " + visited.search(push)); } } } } </code></pre> <p>The problem is that the <code>visited.search</code> method is always returning <code>-1</code>. Here is the log:</p> <pre><code>visited: [Agent.ExampleAgent.Coord@1af6a711] added x 0 y 1 -1 visited: [Agent.ExampleAgent.Coord@1af6a711, Agent.ExampleAgent.Coord@1c727896] added x 1 y 0 -1 visited: [Agent.ExampleAgent.Coord@1af6a711, Agent.ExampleAgent.Coord@1c727896, Agent.ExampleAgent.Coord@5fbd8c6e] added x 1 y 1 -1 visited: [Agent.ExampleAgent.Coord@1af6a711, Agent.ExampleAgent.Coord@1c727896, Agent.ExampleAgent.Coord@5fbd8c6e, Agent.ExampleAgent.Coord@427a8ba4] added x 0 y 0 -1 visited: [Agent.ExampleAgent.Coord@1af6a711, Agent.ExampleAgent.Coord@1c727896, Agent.ExampleAgent.Coord@5fbd8c6e, Agent.ExampleAgent.Coord@427a8ba4, Agent.ExampleAgent.Coord@262f6be5] added x 0 y 1 -1 visited: [Agent.ExampleAgent.Coord@1af6a711, Agent.ExampleAgent.Coord@1c727896, Agent.ExampleAgent.Coord@5fbd8c6e, Agent.ExampleAgent.Coord@427a8ba4, Agent.ExampleAgent.Coord@262f6be5, Agent.ExampleAgent.Coord@199d4a86] </code></pre> <p>Note that the first element that is added to the visited stack is <code>(0,1)</code>, however when it is searched for <code>(0,1)</code>, later the method returns <code>-1</code>.</p>
 

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