treemap

Possible Duplicate: How do I iterate over each Entry in a Map? I want to iterate over a TreeMap , and for all keys which have a particular value, I want them to be added to a new TreeMap . How can I do this? Assuming type TreeMap<String,Integer> : for(Map.Entry<String,Integer> entry : treeMap.entrySet()) { String key = entry.getKey(); Integer value = entry.getValue(); System.out.println(key + " => " + value); } (key and Value types can be any class of course) karim79 //create TreeMap instance TreeMap treeMap = new TreeMap(); //add key value pairs to TreeMap treeMap.put("1","One"); treeMap.put(

I want to create a TreeMap in Java with a custom sort order. The sorted keys which are string need to be sorted according to the second character. The values are also string. Sample map: Za,FOO Ab,Bar polygenelubricants You can use a custom comparator like this: Comparator<String> secondCharComparator = new Comparator<String>() { @Override public int compare(String s1, String s2) { return s1.substring(1, 2).compareTo(s2.substring(1, 2)); } }; Sample: SortedMap<String,String> map = new TreeMap<String,String>(secondCharComparator); map.put("Za", "FOO"); map.put("Ab", "BAR"); map.put("00", "ZERO"

I have a list of objects I need to sort according to properties of one of their fields. I've heard that SortedMap and Comparators are the best way to do this. Do I implement Comparable with the class I'm sorting, or do I create a new class? How do I instantiate the SortedMap and pass in the Comparator? How does the sorting work? Will it automatically sort everything as new objects are inserted? EDIT: This code is giving me an error: private TreeMap<Ktr> collection = new TreeMap<Ktr>(); (Ktr implements Comparator<Ktr> ). Eclipse says it is expecting something like TreeMap<K, V> , so the number

I want to get random keys and their respective values from a Map. The idea is that a random generator would pick a key and display that value. The tricky part is that both key and value will be strings, for example myMap.put("Geddy", "Lee") . HashMap<String, String> x; Random random = new Random(); List<String> keys = new ArrayList<String>(x.keySet()); String randomKey = keys.get( random.nextInt(keys.size()) ); String value = x.get(randomKey); Narendra Yadala This question should be of help to you Is there a way to get the value of a HashMap randomly in Java? and this one also Picking a random

I am working on creating a Treemap from a csv file. The data in the csv file is hierarchical, as a result I used d3.nest() . However, the resulting JSON is in the form of {key:"United States", values:[...]} . The zoom-able treemap requires hierarchy as {name:"United States", children:[...]} . I have tried replacing name and children to key and values in the example, but it doesn't work. If anyone has already looked into using key and values on a zoomable treemap, please help. I am new to D3 and I don't know whether d.children means structure or value from the data. This is the code to convert