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18 package org.apache.log4j.spi;
19
20 import org.apache.log4j.*;
21 import org.apache.log4j.helpers.LogLog;
22
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24
25
26 /***
27 RootLogger sits at the top of the logger hierachy. It is a
28 regular logger except that it provides several guarantees.
29
30 <p>First, it cannot be assigned a <code>null</code>
31 level. Second, since root logger cannot have a parent, the
32 {@link #getChainedLevel} method always returns the value of the
33 level field without walking the hierarchy.
34
35 @author Ceki Gülcü
36
37 */
38 public final class RootLogger extends Logger {
39 /***
40 The root logger names itself as "root". However, the root
41 logger cannot be retrieved by name.
42 */
43 public RootLogger(Level level) {
44 super("root");
45 setLevel(level);
46 }
47
48 /***
49 Return the assigned level value without walking the logger
50 hierarchy.
51 */
52 public final Level getChainedLevel() {
53 return level;
54 }
55
56 /***
57 Setting a null value to the level of the root logger may have catastrophic
58 results. We prevent this here.
59
60 @since 0.8.3 */
61 public final void setLevel(Level level) {
62 if (level == null) {
63 LogLog.error(
64 "You have tried to set a null level to root.", new Throwable());
65 } else {
66 this.level = level;
67 }
68 }
69
70 }