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POHow to update an element in an array that is in an arraylist in java
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  1. POHow to update an element in an array that is in an arraylist in java
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    copied!<p>I have made an ArrayList in Java and put some integers and some doubles in it, then I added an array of integers and an array of doubles. Now I have changed a value of one of the doubles that is in the array, and I want to update it. However, I'm having trouble with coming up with the exact syntax for it, since it's a location within an array within an ArrayList.</p> <p>To be more specific, I have</p> <pre><code>ArrayList&lt;Patch&gt; patches; patches = new ArrayList&lt;Patch&gt;(); //the ArrayList of patches int[] VisPatch; //the array of integers that keeps track of the patchID of the visible patches double[] formFactor; //the array of doubles that keeps track of the formFactor for the visible patches //these are brought in from a file using a scanner int patchID = fin.nextInt(); //the patch number for each patch in the file double emissionPower = fin.nextDouble(); //the emission power of the individual patch double reflectance = fin.nextDouble(); //the reflectance of the individual patch int numVisPatch = fin.nextInt(); //the number of patches that are 'visible' to this particular patch //initialize the arrays that hold the visible patch parameters VisPatch = new int[numVisPatch]; formFactor = new double[numVisPatch]; for(int i=0; i&lt;numVisPatch; i++){ VisPatch[i] = fin.nextInt(); //brought in from file formFactor[i] = fin.nextDouble(); }//end for loop //create a new patch object from the numbers read in patches.add(new Patch(emissionPower, reflectance, numVisPatch, VisPatch, formFactor)); //get the first visible patch in the VisPatch array int adjacentPatchID = patches.get(maxKeyIndex).VisPatch[k]; //maxKeyIndex has been declared, and yes, we're in a for loop that uses k //do some math on the emissionPower double increment = 2; double newEmissionPower = patches.get(adjacentPatchID).emissionPower + increment; //now update the emission power of the patch ummm... </code></pre> <p>I've tried </p> <pre><code>patches.set(adjacentPatchID, newEmissionPower); </code></pre> <p>and</p> <pre><code>patches.set(get(adjacentPatchID).emissionPower, newEmissionPower); </code></pre> <p>and</p> <pre><code>patches.set(adjacentPatchID.emissionPower, newEmissionPower); </code></pre> <p>but my IDE (I'm using Eclipse) just put a bunch of red squiggly lines under everything and says I don't know what I'm talking about (mainly because I don't).</p>
 

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