cop3252 test #2 files, streams, tools, & inner/nested classes

inner classes

have access to outer class members

Scanner (reading from files)

Scanner sc = new Scanner(new File("input.txt"));

package

namespace that organizes related classes and interfaces, like folders for Java files

import packageName.ClassName;      // Import a single class

import packageName.*;              // Import all classes in the package

ObjectInputStream (serialization)

ObjectInputStream in = new ObjectInputStream(new FileInputStream("obj.dat"));

MyClass obj = (MyClass) in.readObject();

ObjectOutputStream (serialization)

ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("obj.dat"));

out.writeObject(myObject);

Formatter (writing formatted text to files)

Formatter fmt = new Formatter("output.txt");

Know how to open an output file and write data to it (write() method)

FileOutputStream fos = new FileOutputStream("output.txt");

fos.write(data);

Know how to open an input file and read data from it (read() method)

FileInputStream fis = new FileInputStream("input.txt");

int data = fis.read();

know what the '.class' file of a nested class looks like

Outer$Inner.class

anonymous inner class

used for one-time class definitions 

-classpath

for specifying the locations of all classes or packages needed (for both javac and java)

-d

for specifying where the result of a javac command will be placed

transient

if an instance variable in an object is declared transient, it will be left out of the serialization 

Serializable

a marker interface, an object can be serialized if its class implements this interface 

serialization of objects

representing an object as a sequence of bytes

Buffered Streams

used to add functionality to other streams and is usually constructed out of other stream objects

random access file

can read/write either sequentially or by accessing single records anywhere in the file

sequential file

typically read or written as an entire file

File

a class used for retrieving properties of files or directories on a disk, does not open files or provide file processing features 

Reader, Writer

character stream input and output

InputStream, OutputStream

byte stream input and output

character streams

text files

byte streams

binary files

output stream

flows from a program to an output destination

input stream

flows from an input source into a program usually to be stored in variables

System.err

standard error stream object

System.out

standard output stream object

System.in

standard input stream object

stream

sequence of data flowing from 1 place to another

static nested classes

access to outer class members is limited

java.lang

automatically part of every program

how to embed an image in such a way that it can also be loaded from a jar file

1.) place the image inside the same package as the class

2.) use getResource to look for the image inside jar at runtime

3.) do not use File since the resource is not an external file