de.weltraumschaf.commons.testing

Class CapturingPrintStream

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

java.io.PrintStream

de.weltraumschaf.commons.testing.CapturingPrintStream

All Implemented Interfaces:

Closeable, Flushable, Appendable, AutoCloseable

public final class CapturingPrintStream
extends PrintStream

Captures the written bytes instead of printing them to any output stream.

This type of object is useful in tests to capture output written to System.out or System.err:

final CapturingPrintStream out = new CapturingPrintStream();
 System.setOut(out);

 // ... executes to code which calls System.out()

 final String output = out.getCapturedOutput();
 

This capturing output streams buffers everything written to OutputStream.write(int), if you want to reset the buffer you must create a new instance.

Since:

1.0.0

Author:

Sven Strittmatter

Field Summary

Fields

Modifier and Type	Field and Description
private ByteArrayOutputStream	capturedOutput Used to collect captured output.
private PrintStream	delegate used to do the real work.
private String	encoding Encoding of the captured bytes.

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Constructors

Constructor and Description
CapturingPrintStream() Creates the print stream with platform encoding.
CapturingPrintStream(String encoding) Dedicated constructor.

Method Summary

Methods

Modifier and Type	Method and Description
PrintStream	append(char c)
PrintStream	append(CharSequence csq)
PrintStream	append(CharSequence csq, int start, int end)
boolean	checkError()
void	close()
void	flush()
PrintStream	format(Locale l, String format, Object... args)
PrintStream	format(String format, Object... args)
String	getCapturedOutput() Returns the whole string of everything written to this stream.
(package private) PrintStream	getDelegate() Only for testing.
void	print(boolean b)
void	print(char c)
void	print(char[] s)
void	print(double d)
void	print(float f)
void	print(int i)
void	print(long l)
void	print(Object obj)
void	print(String s)
PrintStream	printf(Locale l, String format, Object... args)
PrintStream	printf(String format, Object... args)
void	println()
void	println(boolean x)
void	println(char x)
void	println(char[] x)
void	println(double x)
void	println(float x)
void	println(int x)
void	println(long x)
void	println(Object x)
void	println(String x)
CapturingPrintStream	reset() Resets the captured output.
(package private) void	setDelegate(PrintStream delegate) Injection point for testing.
void	write(byte[] buf, int off, int len)
void	write(int b)

Methods inherited from class java.io.PrintStream

clearError, setError

Methods inherited from class java.io.FilterOutputStream

write

Methods inherited from class java.lang.Object

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

Field Detail

capturedOutput

private final ByteArrayOutputStream capturedOutput

Used to collect captured output.

delegate

private PrintStream delegate

used to do the real work.

encoding

private final String encoding

Encoding of the captured bytes.

Constructor Detail

CapturingPrintStream

public CapturingPrintStream()
                     throws UnsupportedEncodingException

Creates the print stream with platform encoding.

Throws:

UnsupportedEncodingException - if the platform encoding is not supported

CapturingPrintStream

public CapturingPrintStream(String encoding)
                     throws UnsupportedEncodingException

Dedicated constructor.

Initializes parents output stream with a dummy stream.

Parameters:

encoding - must not be null or empty

Throws:

UnsupportedEncodingException - if the platform encoding is not supported

Method Detail

getDelegate

PrintStream getDelegate()

Only for testing.

Returns:

never null

setDelegate

void setDelegate(PrintStream delegate)

Injection point for testing.

Parameters:

delegate - must not be null

getCapturedOutput

public String getCapturedOutput()
                         throws UnsupportedEncodingException

Returns the whole string of everything written to this stream.

Returns:

never null

Throws:

UnsupportedEncodingException - if the platform encoding is not supported

reset

public CapturingPrintStream reset()

Resets the captured output.

Returns:

self for chaining

flush

public void flush()

Specified by:

flush in interface Flushable

Overrides:

flush in class PrintStream

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class PrintStream

checkError

public boolean checkError()

Overrides:

checkError in class PrintStream

write

public void write(int b)

Overrides:

write in class PrintStream

write

public void write(byte[] buf,
         int off,
         int len)

Overrides:

write in class PrintStream

print

public void print(boolean b)

Overrides:

print in class PrintStream

print

public void print(char c)

Overrides:

print in class PrintStream

print

public void print(int i)

Overrides:

print in class PrintStream

print

public void print(long l)

Overrides:

print in class PrintStream

print

public void print(float f)

Overrides:

print in class PrintStream

print

public void print(double d)

Overrides:

print in class PrintStream

print

public void print(char[] s)

Overrides:

print in class PrintStream

print

public void print(String s)

Overrides:

print in class PrintStream

print

public void print(Object obj)

Overrides:

print in class PrintStream

println

public void println()

Overrides:

println in class PrintStream

println

public void println(boolean x)

Overrides:

println in class PrintStream

println

public void println(char x)

Overrides:

println in class PrintStream

println

public void println(int x)

Overrides:

println in class PrintStream

println

public void println(long x)

Overrides:

println in class PrintStream

println

public void println(float x)

Overrides:

println in class PrintStream

println

public void println(double x)

Overrides:

println in class PrintStream

println

public void println(char[] x)

Overrides:

println in class PrintStream

println

public void println(String x)

Overrides:

println in class PrintStream

println

public void println(Object x)

Overrides:

println in class PrintStream

printf

public PrintStream printf(String format,
                 Object... args)

Overrides:

printf in class PrintStream

printf

public PrintStream printf(Locale l,
                 String format,
                 Object... args)

Overrides:

printf in class PrintStream

format

public PrintStream format(String format,
                 Object... args)

Overrides:

format in class PrintStream

format

public PrintStream format(Locale l,
                 String format,
                 Object... args)

Overrides:

format in class PrintStream

append

public PrintStream append(CharSequence csq)

Specified by:

append in interface Appendable

Overrides:

append in class PrintStream

append

public PrintStream append(CharSequence csq,
                 int start,
                 int end)

Specified by:

append in interface Appendable

Overrides:

append in class PrintStream

append

public PrintStream append(char c)

Specified by:

append in interface Appendable

Overrides:

append in class PrintStream