File	Doc	Category	Size	Date	Package
SimpleCalcStreamTok.java	API Doc	Example	2856	Wed Mar 10 12:22:26 GMT 2004	None

SimpleCalcStreamTok

• java.lang.Object

Fields Summary
protected StreamTokenizer	tf The StreamTokenizer Input
protected PrintWriter	out The Output File
protected String	variable The variable name (not used in this version)
protected Stack	s The operand stack

Constructors Summary
public SimpleCalcStreamTok(String fileName) Construct by filename this(new FileReader(fileName));
public SimpleCalcStreamTok(Reader rdr) Construct from an existing Reader tf = new StreamTokenizer(rdr); // Control the input character set: tf.slashSlashComments(true); // treat "//" as comments tf.ordinaryChar('-"); // used for subtraction tf.ordinaryChar('/"); // used for division s = new Stack();
public SimpleCalcStreamTok(Reader in, PrintWriter out) Construct from a Reader and a PrintWriter this(in); setOutput(out);

Methods Summary
void	clearStack() s.removeAllElements();
protected void	doCalc() int iType; double tmp; while ((iType = tf.nextToken()) != StreamTokenizer.TT_EOF) { switch(iType) { case StreamTokenizer.TT_NUMBER: // Found a number, push value to stack push(tf.nval); break; case StreamTokenizer.TT_WORD: // Found a variable, save its name. Not used here. variable = tf.sval; break; case '+": // + operator is commutative. push(pop() + pop()); break; case '-": // - operator: order matters. tmp = pop(); push(pop() - tmp); break; case '*": // Multiply is commutative push(pop() * pop()); break; case '/": // Handle division carefully: order matters! tmp = pop(); push(pop() / tmp); break; case '=": out.println(peek()); break; default: out.println("What's this? iType = " + iType); } }
public static void	main(java.lang.String[] av) /* Driver - main program */ if (av.length == 0) new SimpleCalcStreamTok( new InputStreamReader(System.in)).doCalc(); else for (int i=0; i<av.length; i++) new SimpleCalcStreamTok(av[i]).doCalc();
double	peek() return ((Double)s.peek()).doubleValue();
double	pop() return ((Double)s.pop()).doubleValue();
void	push(double val) s.push(new Double(val));
public void	setOutput(java.io.PrintWriter out) Change the output destination. this.out = out;