8.4.8

Examples of Method Declarations

CLASSES

class Test {

public static void main(String[] args) {

Super s = new Sub();

System.out.println(s.greeting() + ", " + s.name());

}

}

produces the output:

Goodnight, Dick

because the invocation of

greeting

 uses the type of

s

, namely

Super

, to figure

out, at compile time, which class method to invoke, whereas the invocation of

name

 uses the class of

s

, namely

Sub

, to figure out, at run time, which instance

method to invoke.

8.4.8.6

Large Example of Overriding

Overriding makes it easy for subclasses to extend the behavior of an existing

class, as shown in this example:

import java.io.OutputStream;

import java.io.IOException;

class BufferOutput {

private OutputStream o;

BufferOutput(OutputStream o) { this.o = o; }

protected byte[] buf = new byte[512];

protected int pos = 0;

public void putchar(char c) throws IOException {

if (pos == buf.length)

flush();

buf[pos++] = (byte)c;

}

public void putstr(String s) throws IOException {

for (int i = 0; i < s.length(); i++)

putchar(s.charAt(i));

}

public void flush() throws IOException {

o.write(buf, 0, pos);

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