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1
39
40 package com.sun.japex;
41
42 import java.io.*;
43 import java.util.*;
44 import java.lang.reflect.*;
45 import java.text.DecimalFormat  ;
46
47 public class Util {
48
49 static final int KB = 1024;
50 static final String spaces = " ";
51
52 static Method currentTime;
53 static boolean unitIsMillis;
54
55 static {
56 try {
58 currentTime = System .class.getMethod("nanoTime", null);
59 unitIsMillis = false;
60 }
61 catch (NoSuchMethodException e) {
62 try {
63 currentTime = System .class.getMethod("currentTimeMillis", null);
64 unitIsMillis = true;
65 }
66 catch (NoSuchMethodException ee) {
67 e.printStackTrace();
68 System.exit(1);
69 }
70 }
71 }
72
73
74 public Util() {
75 }
76
77 static String getSpaces(int length) {
78 return spaces.substring(0, length);
79 }
80
81 static public byte[] streamToByteArray(InputStream is) {
82 ByteArrayOutputStream bos = new ByteArrayOutputStream(8 * KB);
83 int c;
84 try {
85 while ((c = is.read()) != -1) {
86 bos.write(c);
87 }
88 } catch (IOException e) {
89 throw new RuntimeException (e);
90 }
91 return bos.toByteArray();
92 }
93
94 public static long parseDuration(String duration) {
95 try {
96 int length = duration.length();
97 switch (length) {
98 case 1:
99 case 2:
100 return Integer.parseInt(duration.substring(0, length))
102 * 1000;
103 case 5:
104 if (duration.charAt(2) == ':') {
105 return Integer.parseInt(duration.substring(0, 2))
107 * 60 * 1000 +
108 Integer.parseInt(duration.substring(3, 5))
109 * 1000;
110 }
111 break;
112 case 8:
113 if (duration.charAt(2) == ':' && duration.charAt(5) == ':') {
115 return Integer.parseInt(duration.substring(0, 2))
116 * 60 * 60 * 1000 +
117 Integer.parseInt(duration.substring(3, 5))
118 * 60 * 1000 +
119 Integer.parseInt(duration.substring(6, 8))
120 * 1000;
121 }
122 break;
123 }
124 }
125 catch (NumberFormatException e) {
126 }
128 throw new RuntimeException ("Duration '" + duration
129 + "' does not conform to pattern '((HH:)?MM:)?SS'");
130 }
131
132 public static long currentTimeNanos() {
133 try {
134 long t = ((Number ) currentTime.invoke(null, null)).longValue();
135 return unitIsMillis ? millisToNanos(t) : t;
136 }
137 catch (Exception e) {
138 e.printStackTrace();
139 System.exit(1);
140 }
141 return 0;
142 }
143
144 public static long currentTimeMillis() {
145 try {
146 long t = ((Number ) currentTime.invoke(null, null)).longValue();
147 return unitIsMillis ? t : (long) nanosToMillis(t);
148 }
149 catch (Exception e) {
150 e.printStackTrace();
151 System.exit(1);
152 }
153 return 0;
154 }
155
156 public static long millisToNanos(long millis) {
157 return millis * 1000000L;
158 }
159
160 public static double nanosToMillis(long nanos) {
161 return nanos / 1000000.0;
162 }
163
164 public static double arithmeticMean(double[] sample) {
165 double mean = 0.0;
166 for (int i = 0; i < sample.length; i++) {
167 mean += sample[i];
168 }
169 return (mean / sample.length);
170 }
171
172 public static double standardDev(double[] sample) {
173 double mean = arithmeticMean(sample);
174
175 double variance = 0.0;
177 for (int i = 0; i < sample.length; i++) {
178 variance += (sample[i] - mean) * (sample[i] - mean);
179 }
180 variance /= sample.length;
181
182 return Math.sqrt(variance);
184 }
185
186 static DecimalFormat _decimalFormat = new DecimalFormat ("0.00");
187
188 public static String formatDouble(double value) {
189 return _decimalFormat.format(value);
190 }
191 }
192 |
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Java API By Example, From Geeks To Geeks.