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POWrite x bytes with value y to a file in java
 

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  1. POWrite x bytes with value y to a file in java
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    <p>I am trying to write to a file certain number of bytes lets say x bytes, with a value y. The problem is that i am doing it lots of time and I am currently using DataOutputStream with BufferedOutputStream and the write method that gets an array of byte. Each time i allocate a new array of bytes of length x and write it. It is wasteful and I wonder if there is a more efficient way? Thanks.</p> <p>Edit: I have implemented it by allocating a big array that grows by demand, but the problem is that i store it and it might get very big. The code:</p> <pre><code> byte[] block = new byte[4096]; try { for(int i=0; i&lt;nameOccurence.length; ++i){ if(nameOccurence[i] &gt;= block.length){ int size = ((Integer.MAX_VALUE - nameOccurence[i]) &lt;= 0.5*Integer.MAX_VALUE) ? Integer.MAX_VALUE : (nameOccurence[i] * 2); block = new byte[size]; } if(nameOccurence[i] == 0){ namePointer[i] = -1;//i.e. there are no vertices with this name continue; } namePointer[i] = byteCounter; ds.writeInt(nameOccurence[i]); ds.write(block, 0, nameOccurence[i]*2); ds.write(block, 0, nameOccurence[i]*2); byteCounter += (4*((long)nameOccurence[i]))+4;//because we wrote an integer. } </code></pre> <p>where ds is DataOutputStream. Please note that the array block can grow till max int if the nameOccurence[i] is large enough.</p> <p>I think that the best way is to find the max number upon all i in nameOccurence and allocate array of this length. The problem is that it can get Integer.MAX_VALUE.</p> <p>Maybe it will be better to run with a loop and write 1 byte each time? please note that the underlying of DataOuputStream is BufferedOutputStream.</p>
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    1. USJack Stevens
    1. USJack Stevens
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    1. COPlease show us the code you got so far.
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      1. USasgs
    2. COIf you are writing the same value repeatedly, why do you need more then one `byte[]`. If you are using a large `byte[]` why do you need a BuffereOutputStream?
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      1. USPeter Lawrey
    3. COYou can use [`Arrays.fill()`](http://download.oracle.com/javase/6/docs/api/java/util/Arrays.html#fill(byte[],%20byte)) to fill the `byte[]`. But unless this has been **proven** to be a bottleneck, I wouldn't care about it.
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      1. USJoachim Sauer
 

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