I have a project that I'm working on for my Java class (obviously) and I must have missed the lecture on how to interact with TreeMaps. I have no idea what I'm doing with this part and I'm not finding a lot of help from Google.
For the first case in the program, I have to print all values of a TreeMap. The following is the code I was provided and the work I have done with it. Everything in case A is mine, but it isn't working. Any help would be appreciated.
import java.util.Scanner;
import java.util.Set;
import java.util.Map;
import java.util.TreeMap;
import java.io.File;
import java.io.FileNotFoundException;
public class prog7 {
public static void main(String args[])
throws FileNotFoundException
{
Scanner kb=new Scanner(System.in);
/*here, add code to declare and create a tree map*/
TreeMap treeMap = new TreeMap();
/*here, add code to declare a variable and
let it be the key set of the map
*/
String key;
//temporary variables
String tempWord;
String tempDef;
//the following code reads data from the file glossary.txt
//and saves the data as entries in the map
Scanner infile=new Scanner(new File("glossary.txt"));
while(infile.hasNext())
{
tempWord=infile.nextLine();
tempDef=infile.nextLine();
/*here, add code to add tempWord and tempDef
as an entry in the map
*/
treeMap.put(tempWord, tempDef);
}
infile.close();
while(true)
{
System.out.println();
System.out.println();
//show menu and prompt message
System.out.println("Please select one of the following actions:");
System.out.println("q - Quit");
System.out.println("a - List all words and their definitons");
System.out.println("b - Enter a word to find its definition");
System.out.println("c - Add a new entry");
System.out.println("d - Delete an entry");
System.out.println("Please enter q, a, b, c or d:");
String selection=kb.nextLine(); //read user's selection
if (selection.equals("")) continue; //if selection is "", show menu again
switch (selection.charAt(0))
{
case 'q':
System.out.println("\nThank you.");
return;
/*write code for the cases 'a','b','c' and 'd'
so that the program runs as in the sample run
*/
case 'a':
for (String treeKey : treeMap.keySet())
System.out.println(treeKey);
break;
Iterate over the entrySet rather than the keySet. You get a set of Map.Entry<K, V>
which have convenient getKey()
and getValue()
methods.
That said, Java's standard Map implementations have an implementation of toString() that does what you want. Of course, I reckon you'll only get points for reimplementing it, not for cleverly avoiding it...
for (Map.Entry<K, V> entry : myMap.entrySet()) {
System.out.println("Key: " + entry.getKey() + ". Value: " + entry.getValue());
}