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  1. PO
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    <p>What a weird programming ...</p> <p>However, the problem seems to be sitting here:</p> <p>1) In class <code>Game</code> you have a static field of type <code>HashMap&lt;Block, Coordinates&gt;</code> called <em>blocks</em>. You are inserting instances of class <code>Block</code> for the keys into that map. Corresponding line is:</p> <pre><code>blocks.put(new Block(new BlockRectangle(rectID)), new Coordinates(rectx, recty)); </code></pre> <p>2) While also creating an instace of type <code>BlockRectangle</code> in the same line, the constructor puts the object in construction as a key into the the static field of type <code>HashMap&lt;Integer, BlockRectangle&gt;</code> called <em>rects</em>. Corresponding line is:</p> <pre><code>rects.put(id, this); </code></pre> <p>3) Then you are trying to get a Block by calling</p> <pre><code>blocks.get(BlockRectangle.getByID(rectID)) </code></pre> <p>The inner expression <code>BlockRectangle.getByID(rectID)</code> will return a <code>BlockRectangle</code> instance that is looked up in the map <em>rects</em>. With this instance now a lookup is done in the map <em>blocks</em>, but this only stores <code>Block</code>s as keys, not <code>BlockRectangle</code>s (see point 1).</p> <p>Without any <code>equals</code> (and <code>hashCode</code>) method in <code>Block</code> and <code>BlockRectangle</code>, you are not getting any further. But implementing those methods in any of these classes make it worse, as it will not be a good idea to compare blocks with block rectangles.</p> <p>You should do a complete redesign of your software.</p>
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    1. POGetting NullPointerException while creating a game
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    1. USSeelenvirtuose
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    1. COOk, I changed the HashMap in BlockRectangle to HashMap<Integer, Block>, but nothing changed..
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      1. USZygimantas Anon
    2. COCould you tell me how should i fix the error simplier ?
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      1. USZygimantas Anon
    3. COChanging the map in BlockRectangle to HashMap<Integer, Block> does not change anything, as you still store BlockRectangle instances as values inside this map. Maybe you could change the other map to HashMap<BlockRectangle, Coordinates>, and then you should not create a "new Block(...)" that wraps a BlockRectangle, but just use the newly created BlockRectangle as the key. I do not know, if that works. Maybe you know someone, who could work with you on a serious redesign.
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