[1] | 1 | package de.ugoe.cs.util.console;
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| 2 |
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| 3 | import java.util.ArrayList;
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| 4 | import java.util.List;
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| 5 |
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| 6 | import de.ugoe.cs.util.StringTools;
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| 7 |
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| 8 |
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| 9 | /**
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| 10 | * <p>
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| 11 | * This class provides an interface for communication with the user without have
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| 12 | * to rely on a specific user interface. Thus, it can be used to decouple the
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| 13 | * programs logic from its user interface.
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| 14 | * </p>
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| 15 | * <p>
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| 16 | * {@link Command} objects can be used to execute behavior.
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| 17 | * </p>
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| 18 | * <p>
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| 19 | * To send output to the user interface, the Observer pattern is used. The
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| 20 | * Console is an observable, the concrete user interfaces are the observers. The
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| 21 | * interface for the observers is {@link ConsoleObserver}.
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| 22 | * </p>
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| 23 | *
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| 24 | * @author Steffen Herbold
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| 25 | */
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| 26 | public final class Console {
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| 27 |
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| 28 | /**
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| 29 | * <p>
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| 30 | * List of observers.
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| 31 | * </p>
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| 32 | */
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| 33 | private List<ConsoleObserver> observers;
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| 34 |
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| 35 | /**
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| 36 | * <p>
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| 37 | * Handle of the Console instance.
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| 38 | * </p>
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| 39 | */
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| 40 | private static Console theInstance = null;
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| 41 |
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| 42 | /**
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| 43 | * <p>
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| 44 | * Returns the instance of Console. If no instances exists yet, a new one is
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| 45 | * created.
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| 46 | * </p>
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| 47 | *
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| 48 | * @return instance of this class
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| 49 | */
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| 50 | public static Console getInstance() {
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| 51 | if (theInstance == null) {
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| 52 | theInstance = new Console();
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| 53 | }
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| 54 | return theInstance;
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| 55 | }
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| 56 |
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| 57 | /**
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| 58 | * <p>
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| 59 | * Creates a new Console. Private to prevent multiple instances (Singleton).
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| 60 | * </p>
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| 61 | */
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| 62 | private Console() {
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| 63 | observers = new ArrayList<ConsoleObserver>();
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| 64 | }
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| 65 |
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| 66 | /**
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| 67 | * <p>
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| 68 | * Register a new observer.
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| 69 | * </p>
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| 70 | *
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| 71 | * @param observer
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| 72 | * observer to be added
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| 73 | */
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| 74 | public void registerObserver(ConsoleObserver observer) {
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| 75 | observers.add(observer);
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| 76 | }
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| 77 |
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| 78 | /**
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| 79 | * <p>
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| 80 | * Remove an observer. If the observer is not found, nothing is done.
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| 81 | * </p>
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| 82 | *
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| 83 | * @param observer
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| 84 | * observer to be removed
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| 85 | */
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| 86 | public void deleteObserver(ConsoleObserver observer) {
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| 87 | observers.remove(observer);
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| 88 | }
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| 89 |
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| 90 | /**
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| 91 | * <p>
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| 92 | * Sends a message to all observers containing the message that was passed
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| 93 | * to this function.
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| 94 | * </p>
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| 95 | *
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| 96 | * @param msg
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| 97 | * message that is send to the console
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| 98 | */
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| 99 | public static void print(String msg) {
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| 100 | if (theInstance == null) {
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| 101 | getInstance();
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| 102 | }
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| 103 | for (ConsoleObserver observer : theInstance.observers) {
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| 104 | observer.updateText(msg);
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| 105 | }
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| 106 | }
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| 107 |
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| 108 | /**
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| 109 | * <p>
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| 110 | * Sends a message to all observers containing the message that was passed
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| 111 | * to this function and adds an endline to the message.
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| 112 | * </p>
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| 113 | *
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| 114 | * @param msg
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| 115 | * message that is send to the observers
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| 116 | */
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| 117 | public static void println(String msg) {
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| 118 | if (theInstance == null) {
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| 119 | getInstance();
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| 120 | }
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| 121 | for (ConsoleObserver observer : theInstance.observers) {
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| 122 | observer.updateText(msg
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| 123 | + StringTools.ENDLINE);
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| 124 | }
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| 125 | }
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| 126 |
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| 127 | /**
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| 128 | * <p>
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| 129 | * Sends an error message to all observers containing the message that was
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| 130 | * passed to this function.
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| 131 | * </p>
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| 132 | *
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| 133 | * @param errMsg
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| 134 | * message that is send to the observers
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| 135 | */
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| 136 | public static void printerr(String errMsg) {
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| 137 | if (theInstance == null) {
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| 138 | getInstance();
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| 139 | }
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| 140 | for (ConsoleObserver observer : theInstance.observers) {
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| 141 | observer.errStream(errMsg);
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| 142 | }
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| 143 | }
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| 144 |
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| 145 | /**
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| 146 | * <p>
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| 147 | * Sends an error message to all observers containing the message that was
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| 148 | * passed to this function and adds an endline to the message.
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| 149 | * </p>
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| 150 | *
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| 151 | * @param errMsg
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| 152 | * message that is send to the observers
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| 153 | */
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| 154 | public static void printerrln(String errMsg) {
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| 155 | if (theInstance == null) {
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| 156 | getInstance();
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| 157 | }
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| 158 | for (ConsoleObserver observer : theInstance.observers) {
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| 159 | observer.errStream(errMsg
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| 160 | + StringTools.ENDLINE);
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| 161 | }
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| 162 | }
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| 163 |
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| 164 | /**
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| 165 | * <p>
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| 166 | * Sends an exception to all observers to print its stack trace.
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| 167 | * </p>
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| 168 | *
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| 169 | * @param e
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| 170 | * exception whose stack trace is to be printed
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| 171 | */
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| 172 | public static void printStacktrace(Exception e) {
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| 173 | if (theInstance == null) {
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| 174 | getInstance();
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| 175 | }
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| 176 | for (ConsoleObserver observer : theInstance.observers) {
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| 177 | observer.printStacktrace(e);
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| 178 | }
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| 179 | }
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| 180 |
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| 181 | /**
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| 182 | * <p>
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| 183 | * Sends a debug message to all observers containing the message that was
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| 184 | * passed to this function.
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| 185 | * </p>
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| 186 | *
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| 187 | * @param traceMsg
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| 188 | * message that is send to the observers
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| 189 | */
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| 190 | public static void trace(String traceMsg) {
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| 191 | if (theInstance == null) {
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| 192 | getInstance();
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| 193 | }
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| 194 | for (ConsoleObserver observer : theInstance.observers) {
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| 195 | observer.trace(traceMsg);
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| 196 | }
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| 197 | }
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| 198 |
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| 199 | /**
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| 200 | * <p>
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| 201 | * Sends a debug message to all observers containing the message that was
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| 202 | * passed to this function and adds an endline to the message.
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| 203 | * </p>
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| 204 | *
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| 205 | * @param traceMsg
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| 206 | * message that is send to the observers
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| 207 | */
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| 208 | public static void traceln(String traceMsg) {
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| 209 | if (theInstance == null) {
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| 210 | getInstance();
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| 211 | }
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| 212 | for (ConsoleObserver observer : theInstance.observers) {
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| 213 | observer.trace(traceMsg
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| 214 | + StringTools.ENDLINE);
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| 215 | }
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| 216 | }
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| 217 |
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| 218 | }
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