public class TestTreeMapOfStringAndInteger
1: //TestTreeMapOfStringAndInteger.java
2: //Compare the output of this program with that of
3: //TestTreeMapOfStringAndInteger.java and try to
4: //explain the difference(s) that you see.
6: import java.util.TreeMap;
7: import java.util.Scanner;
9: public class TestTreeMapOfStringAndInteger
10: {
11: public static void main(String[] args)
12: {
13: System.out.println("=====1=========================");
14: //Create empty String/Integer TreeMap, then display content and size.
15: TreeMap<String, Integer> treeMap;
16: treeMap = new TreeMap<String, Integer>();
17: System.out.println(treeMap);
18: System.out.println(treeMap.size());
19: pause(1);
21: System.out.println("=====2=========================");
22: //Add one key/value pair and re-display.
23: treeMap.put("Hello", 2);
24: System.out.println(treeMap);
25: System.out.println(treeMap.size());
26: System.out.println(treeMap.get("Hello"));
27: pause(2);
29: System.out.println("=====3=========================");
30: //Add another key/value pair and re-display.
31: if (treeMap.containsKey("Hello"))
32: {
33: treeMap.put("Hello", 5);
34: }
35: System.out.println(treeMap);
37: if (treeMap.containsKey("Good-bye"))
38: {
39: treeMap.put("Good-bye", 5);
40: }
41: else
42: {
43: treeMap.put("Good-bye", 7);
44: }
45: System.out.println(treeMap);
46: System.out.println(treeMap.size());
47: System.out.println(treeMap.get("Hello"));
48: System.out.println(treeMap.get("Good-bye"));
49: pause(3);
51: System.out.println("=====4=========================");
52: //Display all keys, all values and all key/value pairs.
53: //Do it first the pre-Java 8 way ...
54: for (String s : treeMap.keySet())
55: {
56: System.out.print(s + " ");
57: }
58: System.out.println();
59: for (Integer i : treeMap.values())
60: {
61: System.out.print(i + " ");
62: }
63: System.out.println();
64: for (String s : treeMap.keySet())
65: {
66: System.out.println(s + " " + treeMap.get(s));
67: }
68: pause(4);
70: System.out.println("=====5=========================");
71: //Display all keys, all values and all key/value pairs.
72: //Now do it the Java 8 way ...
73: treeMap.keySet().forEach(s -> System.out.print(s + " "));
74: System.out.println();
75: treeMap.values().forEach(i -> System.out.print(i + " "));
76: System.out.println();
77: treeMap.keySet().forEach
78: (
79: s -> System.out.println(s + " " + treeMap.get(s))
80: );
81: pause(5);
82: }
84: public static void pause(int pauseNumber)
85: {
86: Scanner keyboard = new Scanner(System.in);
87: System.out.println("Pause " + pauseNumber);
88: System.out.print("Press Enter to continue ... ");
89: keyboard.nextLine();
90: }
91: }
92: /* Output (without the pauses):
93: =====1=========================
94: {}
95: 0
96: =====2=========================
97: {Hello=2}
98: 1
99: 2
100: =====3=========================
101: {Hello=5}
102: {Good-bye=7, Hello=5}
103: 2
104: 5
105: 7
106: =====4=========================
107: Good-bye Hello
108: 7 5
109: Good-bye 7
110: Hello 5
111: =====5=========================
112: Good-bye Hello
113: 7 5
114: Good-bye 7
115: Hello 5
116: */