-*- coding: utf-8 -*-


       L?sningsforslag til ukeoppgaver til ?velser 1.-5.9.2014


Det finnes selvf?lgelig mange gode l?sninger; her er mine forslag. Om
du tror du har et bedre forslag, h?rer jeg gjerne om det.

(Til spesielt interesserte: Forslagene mine er ikke helt perfekte; hva
kan gi sm?feil i utskriften?)


Oppgave 3a

import java.io.*;

class Classes2 {
    public static void main(String arg[]) {
	for (String fName: arg) {
	    readJavaFile(fName);
	}
    }

    static void readJavaFile(String fName) {
	try {
	    LineNumberReader f = new LineNumberReader(new FileReader(fName));

	    while (true) {
		String line = f.readLine();
		if (line == null) break;

		String className = findClassName(line);
		if (className == null) continue;

		System.out.printf("%-20s%s:%d\n", className, fName, f.getLineNumber());
	    }
	} catch (Exception e) {
	    System.err.println("Read error for "+fName+"!");
	}
    }

    static String findClassName(String t) {
	// Find "class name" and return name.

	String w[] = t.split(" ");
	for (int i = 0;  i <w.length-1;  ++i) {
	    if (w[i].equals("class")) 
		return w[i+1];
	}
	return null;
    }
}


Om man velger ? benytte regul?re uttrykk, kan programmet bli enn?
enklere:

import java.io.*;
import java.util.regex.*;

class Classes {
    public static void main(String arg[]) {
	for (String fName: arg) {
	    try {
		LineNumberReader f = new LineNumberReader(new FileReader(fName));
		
		while (true) {
		    String line = f.readLine();
		    if (line == null) break;

		    Pattern p = Pattern.compile(".*\\bclass\\s+([A-Z]\\w*).*");
		    Matcher m = p.matcher(line);
		    if (m.matches()) {
			System.out.printf("%-20s%s:%d\n", 
					  m.group(1), fName, f.getLineNumber());
		    }
		}
	    } catch (Exception e) {
		System.err.println("Read error for "+fName+"!");
	    }
	}
    }
}


Oppgave 3b

import java.io.*;

class Classes {
    public static void main(String arg[]) {
	for (String fName: arg) {
	    readJavaFile(fName);
	}
    }

    static void readJavaFile(String fName) {
	try {
	    LineNumberReader f = new LineNumberReader(new FileReader(fName));

	    while (true) {
		String line = f.readLine();
		if (line == null) break;

		String className = findClassName(line);
		if (className == null) continue;

		System.out.printf("%-20s%s:%d\n", className, fName, f.getLineNumber());
	    }
	} catch (Exception e) {
	    System.err.println("Read error for "+fName+"!");
	}
    }

    static String findClassName(String t) {
	// Find "class name" and return name.

	String w[] = t.split(" ");
	for (int i = 0;  i <w.length-1;  ++i) {
	    if (w[i].equals("class")) {
		String n = w[i+1];

		// Is it an abstract class?
		if (i>0 && w[i-1].equals("abstract")) n = "["+n+"]";

		return n;
	    }
	}
	return null;
    }
}


Oppgave 3c

import java.io.*;
import java.util.*;

class ClassName {
    String name, fileName;
    int lineNum;
    boolean isAbstract;
    String superClass = null;
    List<ClassName> subClasses = new ArrayList<ClassName>();

    ClassName(String n, boolean a, String s) {
	name = n;  isAbstract = a;  superClass = s;
    }
    
    void print(String indent) {
	System.out.printf("%-26s%s:%d\n",
		indent+(isAbstract ? "["+name+"]" : name), fileName, lineNum);

	for (ClassName sub: subClasses)
	    sub.print(indent+"  ");
    }
}

class Classes {
    static Map<String,ClassName> classes = new TreeMap<String,ClassName>();

    public static void main(String arg[]) {
	for (String fName: arg)
	    readJavaFile(fName);

	printClassNames();
    }

    static void readJavaFile(String fName) {
	try {
	    LineNumberReader f = new LineNumberReader(new FileReader(fName));

	    while (true) {
		String line = f.readLine();
		if (line == null) break;

		ClassName cn = findClassName(line);
		if (cn != null) {
		    cn.fileName = fName;  cn.lineNum = f.getLineNumber();
		    classes.put(cn.name,cn);
		}
	    }
	} catch (Exception e) {
	    System.err.println("Read error for "+fName+"!");
	}
    }

    static void printClassNames() {
	// Find all sub-classes:
	for (ClassName nam: classes.values()) {
	    if (nam.superClass != null)
		classes.get(nam.superClass).subClasses.add(nam);
	}

	// Print all class names:
	for (ClassName nam: classes.values())
	    if (nam.superClass == null) 
		nam.print("");
    }

    static ClassName findClassName(String t) {
	// Find "class name".

	String w[] = t.split(" ");
	for (int i = 0;  i <w.length-1;  ++i) {
	    if (w[i].equals("class")) {
		String nam = w[i+1];
		boolean abstr = false;
		String sup = null;

		// Is it an abstract class?
		if (i>0 && w[i-1].equals("abstract")) 
		    abstr = true;

		// Is it a super-class?
		if (i<w.length-3 && w[i+2].equals("extends"))
		    sup = w[i+3];

		return new ClassName(nam, abstr, sup);
	    }
	}
	return null;
    }
}