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POConsistency of contains method on a HashSet and HashMap
 

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  1. POConsistency of contains method on a HashSet and HashMap
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    <p>Why does containsAll method on a HashSet does not remain consistent if remove is called on the Set whereas a containsValue method on a HashMap remains consistent after a value is removed After a value is removed from a HashSet containsAll returns false even if all values were present where as in case of HashMap the containsValue method returns correct value</p> <pre><code>public static void main(String[] args) { HashSet&lt;String&gt; lookup=new HashSet&lt;String&gt;(); HashMap&lt;Integer,String&gt; findup=new HashMap&lt;Integer,String&gt;(); String[] Alltokens={"This","is","a","programming","test","This","is","a","any","language"}; for(String s:Alltokens) lookup.add(s); String[] tokens={"This","is","a"}; Collection&lt;String&gt; tok=Arrays.asList(tokens); lookup.remove(Alltokens[5]); if(lookup.containsAll(tok)) System.out.print("found"); else System.out.print("NOT found"); Integer i=0; for(String s:Alltokens) findup.put(i++,s); boolean found=true; findup.remove(Alltokens[0]); findup.remove(5); //Edit : trying to remove value whose key is 5 for(String s:tokens) if(!findup.containsValue(s)) found=false; System.out.print("\nIn map " + found); } </code></pre> <p>Output NOT found In map true</p> <p>Is there a way to keep containsAll consistent if remove method is called on the HashSet? Also if a value that was not present in the set is passed to remove method.ContainsAll remains consistent</p> <pre><code> lookup.remove("Alltokens[5]"); if(lookup.containsAll(tok)) </code></pre> <p>//This will be true now where as it is false if a value already present is removed</p> <p>May be it has got to do something with keys in HashMaps and no keys in HashSet.Can you please explain how do they work?</p>
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    1. COThere's something missing after `lookup.remove(Alltokens[5]);`.
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      1. USJoachim Sauer
    2. COThe above code will not compile. You should post the actual code, and you should add `{ }` rather than allowing one-line statements to cause these issues for you, as you refactor your code and they change from one-liners to multi-liners.
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    3. CO@JoachimSauer Sorry the if condition went missing.edited it now
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