Exampleexam 2011

Pruefung.java

package klausur;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class Pruefung {
	public static List<List<String>> transposeList(List<List<String>> list) {
		if (list == null) throw new RuntimeException("Argument Error");
		
		int size = list.get(0).size();
		for (List<String> e : list) {
			if (e.size() != size) {
				throw new RuntimeException("Argument Error");
			}
		}
		
		List<List<String>> result = new ArrayList<List<String>>();
		
		for (int x = 0; x < list.size(); x++) {
			for (int y = 0; y < list.get(x).size(); y++) {
				try {
					result.get(y);
				}
				catch (Exception e) {
					result.add(y, new ArrayList<String>());
				}
				result.get(y).add(x,list.get(x).get(y));
			}
		}
		
		return result;
	}
	
	public static Set<String> symmDiff(Set<String> set1, Set<String> set2) {
		if (set1 == null || set2 == null) throw new RuntimeException("Argument Error");
		
		Set<String> setA = new HashSet<String>(set1);
		setA.removeAll(set2);
		Set<String> setB = new HashSet<String>(set2);
		setB.removeAll(set1);
		
		Set<String> result = new HashSet<String>();
		result.addAll(setA);
		result.addAll(setB);
		
		return result;
	}
	
	public static Set<?> deepCopyTree(Set<?> set) {
		if (set == null) throw new RuntimeException("Argument Error");
		
		Set<Object> result = new HashSet<Object>();
		
		for (Object o : set) {
			if (o instanceof Set) {
				result.add(deepCopyTree((Set<?>)o));
			}
			else {
				result.add(o);
			}
		}
		
		return result;
	}
	
	public static Map<String, List<String>> setToMultiMap(Set<List<String>> set) {
		if (set == null) throw new RuntimeException("Argument Error");
		
		for (List<String> e : set) {
			if (e.size() != 2) {
				throw new RuntimeException("Argument Error");
			}
		}
		
		Map<String, List<String>> result = new HashMap<String, List<String>>();
		
		for (List<String> e : set) {
			if (!result.containsKey(e.get(0))) {
				result.put(e.get(0), new ArrayList<String>());
			}
			result.get(e.get(0)).add(e.get(1));
		}
		
		return result;
	}
}

PruefungTest.java

package klausur;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.junit.Test;
import static org.junit.Assert.*;

public class PruefungTest {
	@Test
	public void testTransposeList() {
		List<List<String>> list = new ArrayList<List<String>>();
		list.add(new ArrayList<String>(Arrays.asList("a","b","c")));
		list.add(new ArrayList<String>(Arrays.asList("x","y","z")));
		
		List<List<String>> expected = new ArrayList<List<String>>();
		expected.add(new ArrayList<String>(Arrays.asList("a","x")));
		expected.add(new ArrayList<String>(Arrays.asList("b","y")));
		expected.add(new ArrayList<String>(Arrays.asList("c","z")));
		
		assertEquals(expected, Pruefung.transposeList(list));
	}
	
	@Test
	public void testSymmDiff() {
		Set<String> set1 = new HashSet<String>(Arrays.asList("a","b"));
		Set<String> set2 = new HashSet<String>(Arrays.asList("b","c"));
		Set<String> expected = new HashSet<String>(Arrays.asList("a","c"));
		
		assertEquals(expected, Pruefung.symmDiff(set1, set2));
	}
	
	@Test
	public void testDeepCopyTree() {
		Set<Object> set = new HashSet<Object>();
		Set<Object> subset = new HashSet<Object>();
		set.add("a");
		set.add(subset);
		subset.add("d");
		subset.add(new HashSet<Object>(Arrays.asList("b","c")));
		
		Set<Object> expected = set;
		
		Set<?> actual = Pruefung.deepCopyTree(set);
		assertFalse(expected == actual);
		assertTrue(actual.equals(expected));
		// assertEquals behauptet die Sets wären ungleich?!?
		//assertEquals(expected, actual);
	}
	
	@Test 
	public void testSetToMultiMap() {
		Set<List<String>> set = new HashSet<List<String>>();
		set.add(new ArrayList<String>(Arrays.asList("Emil","PR1")));
		set.add(new ArrayList<String>(Arrays.asList("Otto","PR2")));
		set.add(new ArrayList<String>(Arrays.asList("Emil","AF")));
		
		Map<String, List<String>> expected = new HashMap<String, List<String>>();
		expected.put("Emil", new ArrayList<String>(Arrays.asList("AF","PR1")));
		expected.put("Otto", new ArrayList<String>(Arrays.asList("PR2")));
		
		assertEquals(expected, Pruefung.setToMultiMap(set));
	}
}