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Yasir Khan
3,937 PointsHow to use HashMap to write to an external txt file
public void writeAMap(HashMap<String, String> map, String filename)
{
if(map != null) {
try (FileWriter writer = new FileWriter(filename, true)) {
for(String key : map.keySet()) {
String value = map.get(key);
if(value == null) {
System.out.println("Warning: Null response for " +
key + " in writeAMap. Using a default.");
value = "I don't know what you mean?";
}
writer.write(key.trim());
writer.write('\n');
writer.write(value.trim());
writer.write('\n');
}
writer.close();
}
catch(IOException e) {
System.out.println("Problem writing file: " + filename +
" in writeAMap");
}
}
else {
System.out.println("Null map passed to writeAMap.");
}
I am then calling this method in another class like the below
public void mapWrite(HashMapmap) { help.writeAMap(map, "responses.txt"); }
Then I am calling the above method to the main method like below.
HashMap key = new HashMap(); instruct.mapWrite(key);
but it isn't working, it compiles fine but it just does not to do anything.
1 Answer
Seth Kroger
56,416 PointsI'd suggest using a debugger to help pinpoint where the code is going wrong. Particularly I'd set a breakpoint before calling the save function (or inside at the top) and examine the map to make sure it's not empty (which is not the same as being null) and has the key/value pairs you expect.
I also note that the snippets you wrote don't all have the <String, String> for the HashMap. Make sure you have that whenever you declare a HashMap to be sure the types are correct.
Derek Markman
16,291 PointsDerek Markman
16,291 PointsI think this link will help you out http://stackoverflow.com/questions/15413467/writing-from-hashmap-to-a-txt-file