<![CDATA[
CSE142 Program Example handout #21
Program file Histogram.java
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// 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
----------------
24: *
25: *
30: *
34: *
35: **
37: *
40: *
43: ***
44: *****
45: ***
46: *
47: *
48: ****
49: *
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: *******
96: **
98: **
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