Exercise:
Every character in the string, computing a number of times
Analysis:
1. Scanner obtain user input string
2. Create Map set, key is a string of characters, value is the number of characters
3. Traversal string, each character acquired
4. using the acquired character, Map collection to determine whether there is key
- key exists:
- By character (key), to obtain value (the number of characters)
- value++
- put (key, value) to the new value stored in the Map collection
- key does not exist:
- put(key,1)
5. Map traversal set, the output
Code
Package Penalty for demo03; Import java.util.HashMap; Import java.util.Scanner; / * Exercise: the number of calculations for each character appears in a string analysis: 1. Scanner captures user input string 2. Create a Map collection, key is a string of characters, value is the number of characters 3. traversal string, each character acquired 4. characters acquired, the key to determining whether there is a set of Map key exists: by the character (key), obtaining value ( number of characters) value ++ pUT (key, value) the value is stored in the new collection Map key does not exist: pUT (key,. 1) 5. the traverse Map set, the output * / public class Demo03MapTest { public static voidmain (String [] args) { // 1. Scanner using the acquired user input string Scanner SC = new new Scanner (the System.in); System.out.println ( "Enter a string:" ); String STR = sc.next (); // 2. Create Map set, key is a string of characters, value is the number of characters in the HashMap <character, Integer> Map = new new the HashMap <> (); // 3. traversal string acquiring each character for ( char C: str.toCharArray ()) { // 4. acquired using characters, set to Map key determines whether or not there iF (map.containsKey (C)) { // key exists Integer value =as map.get (C); value ++ ; map.put (C, value); } the else { // Key absence map.put (C,. 1 ); } } // 5. The traverse Map set, the output for (Character Key: map.keySet ()) { Integer value = as map.get (Key); System.out.println (Key + "=" + value); } } }