Java Dictionary Example

Dictionary class is the abstract class which is parent of any class which uses the key and value pair relationship. The classes like HashTable extends this class for their functionality. Every key and every value is an object. In any one  Dictionary object, every key is associated with at most one value. As a rule, the  equals method should be used by implementations of this class to decide if two keys are the same. Also note that this class has become obsolete, the new implementation has to use the Map interface. Lets look at an example.

In the below example, I have created a “java.txt” file which the example code and reading the text file and printing it.

package javabeat.net.core;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class JavaDictionaryExample {
  public static void main(String args[]) throws IOException,FileNotFoundException{
    BufferedReader bufReader = new BufferedReader(new FileReader(new File(
        "java.txt")));
    String inputLine = null;
    Map dictionaryMap = new HashMap();
    while ((inputLine = bufReader.readLine()) != null) {

      // Here split the input line
      String[] words = inputLine.split("\\s+");
      if (inputLine.equals(""))
        continue;
      for (String wordStr : words) {
        wordStr = wordStr.replace(".", "");
        wordStr = wordStr.replace(",", "");
        if (dictionaryMap.containsKey(wordStr)) {
          Integer val = (Integer)dictionaryMap.get(wordStr);
          dictionaryMap.put(wordStr, val + 1);
        } else
          dictionaryMap.put(wordStr, 1);
      }
    }
    for (Object key : dictionaryMap.keySet())
      System.out.println(key + ": " + dictionaryMap.get(key));
  }
}

Output

1);: 2
: 28
Printing: 1
for: 2
dictionaryget(key));: 1
package: 1
javautilHashMap;: 1
readerclose();: 1
"inputtxt")));: 1
commas: 1
":: 1
main(String: 1
any: 1
empty: 1
import: 5
dots: 1
Hashtable();: 1
key: 1
": 1
else: 1
static: 1
wordreplace("": 2
Map: 2
+: 3
class: 1
inputLine: 1
javabeatnetcore;: 1
dictionarykeySet()): 1
and: 1
input: 1
reader: 1
javaioFileReader;: 1
FileReader(new: 1
args[]): 1
//: 5
String[]: 1
Systemoutprintln(key: 1
String: 1
:: 2
word: 3
lines: 1
Ignore: 1
javaioFile;: 1
=: 9
val: 2
javautilMap;: 1
javaioBufferedReader;: 1
inputLinesplit("\\s+");: 1
line: 1
dictionaryput(word: 2
File(: 1
HashMap();: 1
null): 1
words): 1
while: 1
JavaDictionaryExample: 1
words: 2
if: 2
map: 1
dictionaryget(word);: 1
Remove: 1
null;: 1
BufferedReader(new: 1
all: 1
readerreadLine()): 1
"");: 2
(dictionarycontainsKey(word)): 1
void: 1
continue;: 1
dictionary: 2
the: 2
stored: 1
in: 1
(String: 2
((inputLine: 1
new: 3
BufferedReader: 1
Split: 1
!=: 1
}: 5
(inputLineequals("")): 1
Integer: 1
public: 2
{: 5

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