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copied!<p>Assuming that all your values are of integer type, you should create a <code>HashMap<string,Integer></code> to store variable values, and pass it to your <code>evaluate</code> method:</p> <pre><code>public static void main(String[] args) { NodeList commandList = ... // get your XML from somewhere Map<string,Integer> vars = new HashMap<string,Integer>(); for (Node node : commandList) { evaluate(node, vars); } // At this point, vars contains values of all variables assigned in commands // from the command list } </code></pre> <p>The evaluation should become relatively straightforward:</p> <pre><code>private static Integer evaluate(Node node, Map<string,Integer> vars) { if (node is an assignment) { String varName = ... // get variable name from node Node expr = ... // get the node representing expression being assigned Integer value = evaluate(expr, vars); vars.put(varName, value); return value; } if (node is a variable reference) { String varName = ... // get variable name from node return vars.get(varName); } if (node is an integer constant) { String constVal = ... // Get the representation from XML return Integer.decode(constVal); } if (node is a binary expression) { Node lhs = ... // Get the left-hand side expression from the node Node rhs = ... // Get the right-hand side expression from the node Integer lhsVal = evaluate(lhs, vars); Integer rhsVal = evaluate(rhs, vars); if (operator is plus) { return new Integer(((int)lhsVal) + ((int)rhsVal)); } if (operator is minus) { return new Integer(((int)lhsVal) - ((int)rhsVal)); } if (operator is multiply) { return new Integer(((int)lhsVal) * ((int)rhsVal)); } if (operator is divide) { return new Integer(((int)lhsVal) / ((int)rhsVal)); } // ... and so on } // ... and so on } </code></pre>

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