Log

java.lang.Object
- com.oracle.svm.core.log.Log

All Implemented Interfaces:

AutoCloseable

Direct Known Subclasses:

RealLog
```
public abstract class Log
extends Object
implements AutoCloseable
```
Utility class that provides low-level output methods for basic Java data types (strings and numbers). The methods do not allocate any Java objects or arrays, so that they can be used, e.g., during garbage collection.
The string output methods do not perform platform- or charset-depending conversions. Therefore, the printed strings must not contain any Unicode-characters.
All methods return the Log object they are invoked on, so that output of multiple values can be chained. A typical usage looks like the following:
```
 import static com.oracle.svm.core.log.Log.*;

 void foo(int i, String s) {
   log().string("i: ").signed(i).string(" s: ").string(s).newline();
 }
 
```
This class implements AutoCloseable, not because the log ever gets "closed", but so it can be used to bracket several lines of logging with a try-with-resources statement, e.g.,
```
 try (final Log trace = Log.log()) {
     trace.string("[in myMethod(arg: ".signed(arg).string(")").newline();
     trace.string("  i: ").signed(i);
     trace.string("  j: ").signed(j);
     trace.string("]").newline();
 }
 
```

Field Summary

Fields
Modifier and Type Field and Description

static int LEFT_ALIGN

static int NO_ALIGN

static int RIGHT_ALIGN

Fields
Modifier and Type	Field and Description
`static int`	`LEFT_ALIGN`
`static int`	`NO_ALIGN`
`static int`	`RIGHT_ALIGN`

Constructor Summary

Constructors
Modifier Constructor and Description

protected Log()

Constructors
Modifier	Constructor and Description
`protected`	`Log()`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`abstract Log`	`autoflush(boolean onOrOff)` Turn auto-flushing of the log at every newline on or off.
`abstract Log`	`bool(boolean value)` Prints the strings "true" or "false" depending on the value.
`abstract Log`	`character(char value)` Prints the provided character.
`void`	`close()` An implementation of AutoCloseable.close().
`Log`	`exception(Throwable t)` Prints the provided exception, including a stack trace if available, followed by a newline.
`abstract Log`	`exception(Throwable t, int maxFrames)` Prints the provided exception, including a stack trace if available, with at most the specified number of frames, followed by a newline.
`static void`	`finalizeDefaultLogHandler(org.graalvm.nativeimage.LogHandler handler)` If `ImageSingletons.contains(java.lang.Class<?>)` returns `false` for `LogHandler.class`, then this method installs a `FunctionPointerLogHandler` that delegates to `handler`.
`abstract Log`	`flush()` Forces the log to flush to its destination.
`abstract Log`	`hex(int value)` Prints the value, treated as an unsigned value, in hexadecimal format.
`abstract Log`	`hex(long value)` Prints the value, treated as an unsigned value, in hexadecimal format.
`abstract Log`	`hex(org.graalvm.word.WordBase value)` Prints the value, treated as an unsigned value, in hexadecimal format.
`abstract Log`	`hexdump(org.graalvm.word.PointerBase from, int wordSize, int numWords)` Prints a hexdump.
`Log`	`indent(boolean addOrRemove)` Change current amount of indentation, and then print a newline.
`abstract boolean`	`isEnabled()` Is this log enabled?
`static Log`	`log()` Return the singleton RealLog instance.
`static PrintStream`	`logStream()` Returns the `Log.log()` wrapped as a `PrintStream`.
`abstract Log`	`newline()` Prints the newline character.
`static Log`	`noopLog()` Return the singleton NoopLog instance.
`abstract Log`	`number(long value, int radix, boolean signed)` Prints the value according according to the given format specification.
`abstract Log`	`object(Object value)` Simulates java.lang.String.valueOf(Object obj), but without the call to hashCode().
`abstract Log`	`rational(long numerator, long denominator, long decimals)`
`abstract Log`	`redent(boolean addOrRemove)` Change current amount of indentation.
`static void`	`setLog(RealLog realLog)` Set the singleton RealLog instance (only possible during native image generation).
`abstract Log`	`signed(int value)` Prints the value, treated as a signed value, in decimal format.
`abstract Log`	`signed(long value)` Prints the value, treated as a signed value, in decimal format.
`abstract Log`	`signed(org.graalvm.word.WordBase value)` Prints the value, treated as a signed value, in decimal format.
`abstract Log`	`spaces(int value)` Prints the requested number of spaces, e.g., for indentation.
`Log`	`string(byte[] value)` Prints all bytes in the array, without any conversion.
`abstract Log`	`string(byte[] value, int offset, int length)` Prints the provided range of bytes in the array, without any conversion.
`abstract Log`	`string(org.graalvm.nativeimage.c.type.CCharPointer value)` Prints the C string.
`abstract Log`	`string(char[] value)` Prints all characters in the array, without any platform- or charset-depending conversions.
`abstract Log`	`string(String value)` Prints all characters in the string, without any platform- or charset-depending conversions.
`abstract Log`	`string(String str, int fill, int align)` Prints all characters in the string, filling with spaces before or after.
`abstract Log`	`unsigned(int value)` Prints the value, treated as an unsigned value, in decimal format.
`abstract Log`	`unsigned(long value)` Prints the value, treated as an unsigned value, in decimal format.
`abstract Log`	`unsigned(long value, int fill, int align)` Prints the value, treated as an unsigned value, filing spaces before or after.
`abstract Log`	`unsigned(org.graalvm.word.WordBase value)` Prints the value, treated as an unsigned value, in decimal format.
`abstract Log`	`unsigned(org.graalvm.word.WordBase value, int fill, int align)` Prints the value, treated as an unsigned value, filing spaces before or after.
`abstract Log`	`zhex(byte value)` Prints the value, treated as an unsigned value, in hexadecimal format zero filled to 2-digits.
`abstract Log`	`zhex(int value)` Prints the value, treated as an unsigned value, in hexadecimal format zero filled to 8-digits.
`abstract Log`	`zhex(long value)` Prints the value, treated as an unsigned value, in hexadecimal format zero filled to 16-digits.
`abstract Log`	`zhex(short value)` Prints the value, treated as an unsigned value, in hexadecimal format zero filled to 4-digits.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - NO_ALIGN
```
public static final int NO_ALIGN
```
    See Also:
    
    Constant Field Values
  - LEFT_ALIGN
```
public static final int LEFT_ALIGN
```
    See Also:
    
    Constant Field Values
  - RIGHT_ALIGN
```
public static final int RIGHT_ALIGN
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - Log
```
protected Log()
```
- Method Detail
  - finalizeDefaultLogHandler
```
public static void finalizeDefaultLogHandler(org.graalvm.nativeimage.LogHandler handler)
```
    If ImageSingletons.contains(java.lang.Class<?>) returns false for LogHandler.class, then this method installs a FunctionPointerLogHandler that delegates to handler.
  - setLog
```
public static void setLog(RealLog realLog)
```
    Set the singleton RealLog instance (only possible during native image generation).
  - log
```
public static Log log()
```
    Return the singleton RealLog instance.
  - logStream
```
public static PrintStream logStream()
```
    Returns the Log.log() wrapped as a PrintStream.
  - noopLog
```
public static Log noopLog()
```
    Return the singleton NoopLog instance.
  - isEnabled
```
public abstract boolean isEnabled()
```
    Is this log enabled?
  - string
```
public abstract Log string(String value)
```
    Prints all characters in the string, without any platform- or charset-depending conversions.
  - string
```
public abstract Log string(String str,
                           int fill,
                           int align)
```
    Prints all characters in the string, filling with spaces before or after.
  - string
```
public abstract Log string(char[] value)
```
    Prints all characters in the array, without any platform- or charset-depending conversions.
  - string
```
public final Log string(byte[] value)
```
    Prints all bytes in the array, without any conversion.
  - string
```
public abstract Log string(byte[] value,
                           int offset,
                           int length)
```
    Prints the provided range of bytes in the array, without any conversion.
  - string
```
public abstract Log string(org.graalvm.nativeimage.c.type.CCharPointer value)
```
    Prints the C string.
  - character
```
public abstract Log character(char value)
```
    Prints the provided character.
  - newline
```
public abstract Log newline()
```
    Prints the newline character.
  - autoflush
```
public abstract Log autoflush(boolean onOrOff)
```
    Turn auto-flushing of the log at every newline on or off. Default is off.
    
    Parameters:
    
    onOrOff - true if auto-flush must be turned on, false otherwise.
  - number
```
public abstract Log number(long value,
                           int radix,
                           boolean signed)
```
    Prints the value according according to the given format specification. The digits '0' to '9' followed by the letters 'a' to 'z' are used to represent the digits.
    
    Parameters:
    
    value - The value to print.
    
    radix - The base of the value, between 2 and 36.
    
    signed - true if the value should be treated as a signed value (and the digits are preceded by '-' for negative values).
  - signed
```
public abstract Log signed(org.graalvm.word.WordBase value)
```
    Prints the value, treated as a signed value, in decimal format.
  - signed
```
public abstract Log signed(int value)
```
    Prints the value, treated as a signed value, in decimal format.
  - signed
```
public abstract Log signed(long value)
```
    Prints the value, treated as a signed value, in decimal format.
  - unsigned
```
public abstract Log unsigned(org.graalvm.word.WordBase value)
```
    Prints the value, treated as an unsigned value, in decimal format.
  - unsigned
```
public abstract Log unsigned(org.graalvm.word.WordBase value,
                             int fill,
                             int align)
```
    Prints the value, treated as an unsigned value, filing spaces before or after.
  - unsigned
```
public abstract Log unsigned(int value)
```
    Prints the value, treated as an unsigned value, in decimal format.
  - unsigned
```
public abstract Log unsigned(long value)
```
    Prints the value, treated as an unsigned value, in decimal format.
  - unsigned
```
public abstract Log unsigned(long value,
                             int fill,
                             int align)
```
    Prints the value, treated as an unsigned value, filing spaces before or after.
  - rational
```
public abstract Log rational(long numerator,
                             long denominator,
                             long decimals)
```
  - hex
```
public abstract Log hex(org.graalvm.word.WordBase value)
```
    Prints the value, treated as an unsigned value, in hexadecimal format.
  - hex
```
public abstract Log hex(int value)
```
    Prints the value, treated as an unsigned value, in hexadecimal format.
  - hex
```
public abstract Log hex(long value)
```
    Prints the value, treated as an unsigned value, in hexadecimal format.
  - zhex
```
public abstract Log zhex(long value)
```
    Prints the value, treated as an unsigned value, in hexadecimal format zero filled to 16-digits.
  - zhex
```
public abstract Log zhex(int value)
```
    Prints the value, treated as an unsigned value, in hexadecimal format zero filled to 8-digits.
  - zhex
```
public abstract Log zhex(short value)
```
    Prints the value, treated as an unsigned value, in hexadecimal format zero filled to 4-digits.
  - zhex
```
public abstract Log zhex(byte value)
```
    Prints the value, treated as an unsigned value, in hexadecimal format zero filled to 2-digits.
  - hexdump
```
public abstract Log hexdump(org.graalvm.word.PointerBase from,
                            int wordSize,
                            int numWords)
```
    Prints a hexdump.
    
    Parameters:
    
    from - pointer to memory where dumping should start from
    
    wordSize - size in bytes that a single word should have
    
    numWords - number of words to dump
  - redent
```
public abstract Log redent(boolean addOrRemove)
```
    Change current amount of indentation. Indentation determines the amount of spaces emitted after each newline.
  - indent
```
public final Log indent(boolean addOrRemove)
```
    Change current amount of indentation, and then print a newline.
  - bool
```
public abstract Log bool(boolean value)
```
    Prints the strings "true" or "false" depending on the value.
  - object
```
public abstract Log object(Object value)
```
    Simulates java.lang.String.valueOf(Object obj), but without the call to hashCode().
  - spaces
```
public abstract Log spaces(int value)
```
    Prints the requested number of spaces, e.g., for indentation.
  - exception
```
public Log exception(Throwable t)
```
    Prints the provided exception, including a stack trace if available, followed by a newline.
  - exception
```
public abstract Log exception(Throwable t,
                              int maxFrames)
```
    Prints the provided exception, including a stack trace if available, with at most the specified number of frames, followed by a newline.
  - flush
```
public abstract Log flush()
```
    Forces the log to flush to its destination.
  - close
```
public void close()
```
    An implementation of AutoCloseable.close().
    
    Specified by:
    
    close in interface AutoCloseable

Class Log

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

NO_ALIGN

LEFT_ALIGN

RIGHT_ALIGN

Constructor Detail

Log

Method Detail

finalizeDefaultLogHandler

setLog

log

logStream

noopLog

isEnabled

string

string

string

string

string

string

character

newline

autoflush

number

signed

signed

signed

unsigned

unsigned

unsigned

unsigned

unsigned

rational

hex

hex

hex

zhex

zhex

zhex

zhex

hexdump

redent

indent

bool

object

spaces

exception

exception

flush

close