com.google.gwt.core.ext

## Class TreeLogger

- java.lang.Object
- - com.google.gwt.core.ext.TreeLogger

    public abstract class TreeLogger
    extends java.lang.Object

An interface used to log messages in deferred binding generators.

### Nested Class Summary

Nested Classes
`static class` `TreeLogger.HelpInfo` Provides extra information to the user, generally details of what caused the problem or what the user should do to fix the problem.
`static class` `TreeLogger.Type` A type-safe enum of all possible logging severity types.

### Field Summary

Fields
`static TreeLogger.Type` `ALL` Logs everything -- quite a bit of stuff.
`static TreeLogger.Type` `DEBUG` Logs detailed information that could be useful during debugging.
`static TreeLogger.Type` `ERROR` Logs an error.
`static TreeLogger.Type` `INFO` Logs information.
`static TreeLogger` `NULL` A valid logger that ignores all messages.
`static TreeLogger.Type` `SPAM` Logs extremely verbose and detailed information that is typically useful only to product implementors.
`static TreeLogger.Type` `TRACE` Logs information related to lower-level operation.
`static TreeLogger.Type` `WARN` Logs a warning.

### Constructor Summary

Constructors
Constructor and Description
`TreeLogger()`

### Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
`TreeLogger` `branch(TreeLogger.Type type, java.lang.String msg)` Calls `branch(com.google.gwt.core.ext.TreeLogger.Type, String, Throwable, com.google.gwt.core.ext.TreeLogger.HelpInfo)` with a `null` `caught` and `helpInfo`.
`TreeLogger` `branch(TreeLogger.Type type, java.lang.String msg, java.lang.Throwable caught)` Calls `branch(com.google.gwt.core.ext.TreeLogger.Type, String, Throwable, com.google.gwt.core.ext.TreeLogger.HelpInfo)` with a `null` `helpInfo`.
`abstract TreeLogger` `branch(TreeLogger.Type type, java.lang.String msg, java.lang.Throwable caught, TreeLogger.HelpInfo helpInfo)` Produces a branched logger, which can be used to write messages that are logically grouped together underneath the current logger.
`abstract boolean` `isLoggable(TreeLogger.Type type)` Determines whether or not a log entry of the specified type would actually be logged.
`void` `log(TreeLogger.Type type, java.lang.String msg)` Calls `log(TreeLogger.Type, String, Throwable, HelpInfo)` with a `null` `caught` and `helpInfo`.
`void` `log(TreeLogger.Type type, java.lang.String msg, java.lang.Throwable caught)` Calls `log(TreeLogger.Type, String, Throwable, HelpInfo)` with a `null` `helpInfo`.
`abstract void` `log(TreeLogger.Type type, java.lang.String msg, java.lang.Throwable caught, TreeLogger.HelpInfo helpInfo)` Logs a message and/or an exception, with optional help info.

### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

### Field Detail

#### ERROR

    public static final TreeLogger.Type ERROR

Logs an error.

#### WARN

    public static final TreeLogger.Type WARN

Logs a warning.

#### INFO

    public static final TreeLogger.Type INFO

Logs information.

#### TRACE

    public static final TreeLogger.Type TRACE

Logs information related to lower-level operation.

#### DEBUG

    public static final TreeLogger.Type DEBUG

Logs detailed information that could be useful during debugging.

#### SPAM

    public static final TreeLogger.Type SPAM

Logs extremely verbose and detailed information that is typically useful only to product implementors.

#### ALL

    public static final TreeLogger.Type ALL

Logs everything -- quite a bit of stuff.

#### NULL

    public static final TreeLogger NULL

A valid logger that ignores all messages. Occasionally useful when calling methods that require a logger parameter.

### Constructor Detail

#### TreeLogger

    public TreeLogger()

### Method Detail

#### branch

    public final TreeLogger branch(TreeLogger.Type type,
                                   java.lang.String msg)

Calls `branch(com.google.gwt.core.ext.TreeLogger.Type, String, Throwable, com.google.gwt.core.ext.TreeLogger.HelpInfo)` with a `null` `caught` and `helpInfo`.

#### branch

    public final TreeLogger branch(TreeLogger.Type type,
                                   java.lang.String msg,
                                   java.lang.Throwable caught)

Calls `branch(com.google.gwt.core.ext.TreeLogger.Type, String, Throwable, com.google.gwt.core.ext.TreeLogger.HelpInfo)` with a `null` `helpInfo`.

#### branch

    public abstract TreeLogger branch(TreeLogger.Type type,
                                      java.lang.String msg,
                                      java.lang.Throwable caught,
                                      TreeLogger.HelpInfo helpInfo)

Produces a branched logger, which can be used to write messages that are logically grouped together underneath the current logger. The details of how/if the resulting messages are displayed is implementation-dependent.

The log message supplied when branching serves two purposes. First, the message should be considered a heading for all the child messages below it. Second, the `type` of the message provides a hint as to the importance of the children below it. As an optimization, an implementation could return a "no-op" logger if messages of the specified type weren't being logged, which the implication being that all nested log messages were no more important than the level of their branch parent.

As an example of how hierarchical logging can be used, a branched logger in a GUI could write log message as child items of a parent node in a tree control. If logging to streams, such as a text console, the branched logger could prefix each entry with a unique string and indent its text so that it could be sorted later to reconstruct a proper hierarchy.

Parameters:
  `type` -
  `msg` - an optional message to log, which can be `null` if only an exception is being logged
  `caught` - an optional exception to log, which can be `null` if only a message is being logged
  `helpInfo` - extra information that might be used by the logger to provide extended information to the user
Returns:
  an instance of `TreeLogger` representing the new branch of the log; may be the same instance on which this method is called

#### isLoggable

    public abstract boolean isLoggable(TreeLogger.Type type)

Determines whether or not a log entry of the specified type would actually be logged. Caller use this method to avoid constructing log messages that would be thrown away.

#### log

    public final void log(TreeLogger.Type type,
                          java.lang.String msg)

Calls `log(TreeLogger.Type, String, Throwable, HelpInfo)` with a `null` `caught` and `helpInfo`.

#### log

    public final void log(TreeLogger.Type type,
                          java.lang.String msg,
                          java.lang.Throwable caught)

Calls `log(TreeLogger.Type, String, Throwable, HelpInfo)` with a `null` `helpInfo`.

#### log

    public abstract void log(TreeLogger.Type type,
                             java.lang.String msg,
                             java.lang.Throwable caught,
                             TreeLogger.HelpInfo helpInfo)

Logs a message and/or an exception, with optional help info. It is also legal to call this method using `null` arguments for both `msg` and `caught`, in which case the log event can be ignored. The `info` can provide extra information to the logger; a logger may choose to ignore this info.

Parameters:
  `type` -
  `msg` - an optional message to log, which can be `null` if only an exception is being logged
  `caught` - an optional exception to log, which can be `null` if only a message is being logged
  `helpInfo` - extra information that might be used by the logger to provide extended information to the user