Java tutorial
/* ==================================================================== Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ==================================================================== */ package org.apache.poi.ss.formula.udf; import java.util.HashMap; import java.util.Locale; import java.util.Map; import org.apache.poi.ss.formula.functions.FreeRefFunction; /** * Default UDF finder - for adding your own user defined functions. * * @author PUdalau */ public final class DefaultUDFFinder implements UDFFinder { private final Map<String, FreeRefFunction> _functionsByName; public DefaultUDFFinder(String[] functionNames, FreeRefFunction[] functionImpls) { int nFuncs = functionNames.length; if (functionImpls.length != nFuncs) { throw new IllegalArgumentException("Mismatch in number of function names and implementations"); } HashMap<String, FreeRefFunction> m = new HashMap<>(nFuncs * 3 / 2); for (int i = 0; i < functionImpls.length; i++) { m.put(functionNames[i].toUpperCase(Locale.ROOT), functionImpls[i]); } _functionsByName = m; } @Override public FreeRefFunction findFunction(String name) { return _functionsByName.get(name.toUpperCase(Locale.ROOT)); } }