org.eclipse.tracecompass.common.core/src/org/eclipse/tracecompass/common/core/NonNullUtils.java

   1 /*******************************************************************************
   2  * Copyright (c) 2014 Ericsson
   3  *
   4  * All rights reserved. This program and the accompanying materials are
   5  * made available under the terms of the Eclipse Public License v1.0 which
   6  * accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *   Alexandre Montplaisir - Initial API and implementation
  11  *******************************************************************************/
  12
  13 package org.eclipse.tracecompass.common.core;
  14
  15 import org.eclipse.jdt.annotation.NonNull;
  16 import org.eclipse.jdt.annotation.Nullable;
  17
  18 /**
  19  * Utility methods to handle {@link org.eclipse.jdt.annotation.NonNull}
  20  * annotations.
  21  *
  22  * @author Alexandre Montplaisir
  23  */
  24 public final class NonNullUtils {
  25
  26     private NonNullUtils() {}
  27
  28     /**
  29      * Convert a potentially null string into an empty one if it is null.
  30      *
  31      * @param str
  32      *            The string to null-check, and convert to an empty string if
  33      *            null.
  34      * @return The non-null string
  35      */
  36     public static String nullToEmptyString(@Nullable String str) {
  37         if (str == null) {
  38             return ""; //$NON-NLS-1$
  39         }
  40         return str;
  41     }
  42
  43     /**
  44      * Convert a non-annotated object reference to a {@link NonNull} one.
  45      *
  46      * If the reference is actually null, a {@link NullPointerException} is
  47      * thrown. This is usually more desirable than letting an unwanted null
  48      * reference go through and fail much later.
  49      *
  50      * @param obj
  51      *            The object that is supposed to be non-null
  52      * @return A {@link NonNull} reference to the same object
  53      * @throws NullPointerException
  54      *             If the reference was actually null
  55      */
  56     public static <T> T checkNotNull(@Nullable T obj) {
  57         if (obj == null) {
  58             throw new NullPointerException();
  59         }
  60         return obj;
  61     }
  62 }