File	Doc	Category	Size	Date	Package
RandomUtils.java	API Doc	Azureus 3.0.3.4	4274	Thu Jan 11 10:18:16 GMT 2007	org.gudy.azureus2.core3.util

RandomUtils

• java.lang.Object

Fields Summary
public static final Random	RANDOM
public static final int	LISTEN_PORT_MIN
public static final int	LISTEN_PORT_MAX

Constructors Summary

Methods Summary
public static java.lang.String	generateRandomAlphanumerics(int num_to_generate) Generate a random string of charactors. param num_to_generate number of chars to generate return random char string String alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; StringBuffer buff = new StringBuffer( num_to_generate ); for( int i=0; i < num_to_generate; i++ ) { int pos = (int)( RANDOM.nextDouble() * alphabet.length() ); buff.append( alphabet.charAt( pos ) ); } return buff.toString();
public static byte[]	generateRandomBytes(int num_to_generate) Generate a random array of bytes. param num_to_generate number of bytes to generate return random byte array byte[] id = new byte[ num_to_generate ]; RANDOM.nextBytes( id ); return id;
public static int	generateRandomIntBetween(int min, int max) return random int between min and max, e.g params of [5,7] returns 5,6 or 7 return min +generateRandomIntUpto(max + 1 - min);
public static int	generateRandomIntUpto(int max) return random int between 0 and max-1. e.g. param of 10 returns 0->9 return nextInt(max);
public static int	generateRandomNetworkListenPort() Generate a random port number for binding a network IP listening socket to. NOTE: Will return a valid non-privileged port number >= LISTEN_PORT_MIN and <= LISTEN_PORT_MAX. return random port number // DON'T use NetworkManager methods to get the ports here else startup can hang int existing_tcp = COConfigurationManager.getIntParameter( "TCP.Listen.Port" ); int existing_udp = COConfigurationManager.getIntParameter( "UDP.Listen.Port" ); int existing_udp2 = COConfigurationManager.getIntParameter( "UDP.NonData.Listen.Port" ); while( true ){ int min = LISTEN_PORT_MIN; int port = min + RANDOM.nextInt( LISTEN_PORT_MAX + 1 - min ); // skip magnet ports if ( port >= 45100 && port <= 45110 ){ continue; } if ( port != existing_tcp && port != existing_udp && port != existing_udp2){ return port; } }
public static int	generateRandomPlusMinus1() Generates a random +1 or -1 return +1 or -1 return RANDOM.nextBoolean() ? -1:1;
public static byte	nextByte() return (byte)RANDOM.nextInt();
public static void	nextBytes(byte[] bytes) RANDOM.nextBytes(bytes);
public static float	nextFloat() return RANDOM.nextFloat();
public static int	nextInt(int n) return RANDOM.nextInt(n);
public static int	nextInt() return RANDOM.nextInt();
public static long	nextLong() return RANDOM.nextLong();