<![CDATA[
CSE142 Program Example handout #21
Program file Histogram.java
---------------------------
// Stuart Reges
// 2/18/05
//
// This program reads an input file of test scores (integers) and displays a
// histogram of the score distribution.
import java.io.*;
import java.awt.*;
import java.util.*;
public class Histogram {
public static final int MAX_SCORE = 100; // max possible score
public static void main(String[] args) throws FileNotFoundException {
Scanner input = new Scanner(new File("histogram.txt"));
// read file into count array
int[] count = new int[MAX_SCORE + 1];
while (input.hasNextInt()) {
count[input.nextInt()]++;
}
// use array to produce a histogram
for (int i = 0; i < count.length; i++) {
if (count[i] != 0) {
System.out.print(i + ": ");
for (int j = 1; j <= count[i]; j++) {
System.out.print("*");
}
System.out.println();
}
}
draw(count);
}
// Uses a DrawingPanel to draw the histogram
public static void draw(int[] count) {
DrawingPanel p = new DrawingPanel(count.length * 3 + 6, 200);
Graphics g = p.getGraphics();
g.setColor(Color.BLACK);
for (int i = 0; i < count.length; i++) {
g.drawLine(i * 3 + 3, 175, i * 3 + 3, 175 - 5 * count[i]);
}
}
}
Histogram output
----------------
19: *
30: *
31: *
32: *
35: **
40: **
42: *
43: *
44: *
46: *
47: *
50: ***
51: **
52: *
53: **
54: ***
55: ***
56: **
57: **
58: *****
59: *
60: *****
61: ***
62: *
63: ***
64: ******
65: ****
66: ****
67: ***
68: *****
69: *******
70: **
71: ***********
72: ***********
73: ************
74: ******
75: **********
76: *************
77: **************
78: ********
79: ***************
80: *************
81: ***********
82: ************
83: ***********
84: **********************
85: ***************************
86: ********************
87: ********************************
88: ***************
89: ****************
90: ***************
91: *********
92: **********
93: ***********
94: ************
95: ***********
96: **
97: *******
98: **
99: *
100: *****
]]>
