Java
Get flash to fully experience Pearltrees
High performance
executable
java.util.*
Interfaces
GUI
Files
Data Types
Debug Tomcat using Eclipse
Java
// Get current time long start = System.currentTimeMillis(); // Do something ... // Get elapsed time in milliseconds long elapsedTimeMillis = System.currentTimeMillis()-start; // Get elapsed time in seconds float elapsedTimeSec = elapsedTimeMillis/1000F; // Get elapsed time in minutes float elapsedTimeMin = elapsedTimeMillis/(60*1000F); // Get elapsed time in hours float elapsedTimeHour = elapsedTimeMillis/(60*60*1000F); // Get elapsed time in days float elapsedTimeDay = elapsedTimeMillis/(24*60*60*1000F);
Computing Elapsed Time
Random Numbers
Java has a rich toolkit for generating random numbers, in a class named "Random". This document is a quick guide to using Random. Random can generate many kinds of random number, not all of which I discuss here. The best way to think of class Random is that its instances are random number generator objects -- objects that go around spitting out random numbers of various sorts in response to messages from their clients. However, in using this constructor you should recognize that algorithmic random number generators are not truly random, they are really algorithms that generate a fixed but random-looking sequence of numbers. When you create a random number generator, it initializes its sequence from a value called its "seed".
Oracle acquired Sun in 2010, and since that time Oracle's hardware and software engineers have worked side-by-side to build fully integrated systems and optimized solutions designed to achieve performance levels that are unmatched in the industry. Early examples include the Oracle Exadata Database Machine X2-8 , and the first Oracle Exalogic Elastic Cloud , both introduced in late 2010. During 2011, Oracle introduced the SPARC SuperCluster T4-4 , a general-purpose, engineered system with Oracle Solaris that delivered record-breaking performance on a series of enterprise benchmarks. Oracle's SPARC-based systems are some of the most scalable, reliable, and secure products available today. Sun's prized software portfolio has continued to develop as well, with new releases of Oracle Solaris , MySQL , and the recent introduction of Java 7 . Oracle invests in innovation by designing hardware and software systems that are engineered to work together.
Java Technology
execute shell command
//execute shell commands from java String cmd = " ls -al "; Runtime run = Runtime . getRuntime (); Process pr = run . exec ( cmd ); pr . waitFor (); BufferedReader buf = new BufferedReader ( new InputStreamReader ( pr . getInputStream ())); String line = " "; while (( line = buf . readLine ())!= null ) { System . out . println ( line ); }
Students in Prof. Baldwin's Introductory Java Programming classes at ACC are responsible for knowing and understanding all of the material in this lesson (except that they are not responsible for detailed information that is specific to C++). The detailed material on C++ is provided as supplementary material for the benefit of those persons who are already familiar with C++ and who are making the transition into Java.