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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.*;
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
----------------
17: *
19: *
28: **
31: *
32: *
33: *
37: *
38: **
39: *
43: *
44: *
46: *
47: **
48: *
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: ***
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