int max = 10;
int min = 5;
java.util.Ramdom rand = new java.util.Random(System.currentTimeMillis()):
int result = min + rand.nextInt(max - min);
以上代码产生5~10的整数.
如果要自已写Random类,可以参考java.util.Random的源代码
int min = 5;
java.util.Ramdom rand = new java.util.Random(System.currentTimeMillis()):
int result = min + rand.nextInt(max - min);
以上代码产生5~10的整数.
如果要自已写Random类,可以参考java.util.Random的源代码
public class Random implements java.io.Serializable {
static final long serialVersionUID = 3905348978240129619L;
private long seed;
private final static long multiplier = 0x5DEECE66DL;
private final static long addend = 0xBL;
private final static long mask = (1L << 48) - 1;
public Random() { this(System.currentTimeMillis()); }
public Random(long seed) {
setSeed(seed);
} synchronized public void setSeed(long seed) {
this.seed = (seed ^ multiplier) & mask;
haveNextNextGaussian = false;
} synchronized protected int next(int bits) {
long nextseed = (seed * multiplier + addend) & mask;
seed = nextseed;
return (int)(nextseed >>> (48 - bits));
} private static final int BITS_PER_BYTE = 8;
private static final int BYTES_PER_INT = 4; public void nextBytes(byte[] bytes) {
int numRequested = bytes.length; int numGot = 0, rnd = 0; while (true) {
for (int i = 0; i < BYTES_PER_INT; i++) {
if (numGot == numRequested)
return; rnd = (i==0 ? next(BITS_PER_BYTE * BYTES_PER_INT)
: rnd >> BITS_PER_BYTE);
bytes[numGot++] = (byte)rnd;
}
}
} public int nextInt() { return next(32); } public int nextInt(int n) {
if (n<=0)
throw new IllegalArgumentException("n must be positive"); if ((n & -n) == n) // i.e., n is a power of 2
return (int)((n * (long)next(31)) >> 31); int bits, val;
do {
bits = next(31);
val = bits % n;
} while(bits - val + (n-1) < 0);
return val;
} public long nextLong() {
return ((long)(next(32)) << 32) + next(32);
} public boolean nextBoolean() {return next(1) != 0;} public float nextFloat() {
int i = next(24);
return i / ((float)(1 << 24));
} public double nextDouble() {
long l = ((long)(next(26)) << 27) + next(27);
return l / (double)(1L << 53);
} private double nextNextGaussian;
private boolean haveNextNextGaussian = false; synchronized public double nextGaussian() {
if (haveNextNextGaussian) {
haveNextNextGaussian = false;
return nextNextGaussian;
} else {
double v1, v2, s;
do {
v1 = 2 * nextDouble() - 1; // between -1 and 1
v2 = 2 * nextDouble() - 1; // between -1 and 1
s = v1 * v1 + v2 * v2;
} while (s >= 1 || s == 0);
double multiplier = Math.sqrt(-2 * Math.log(s)/s);
nextNextGaussian = v2 * multiplier;
haveNextNextGaussian = true;
return v1 * multiplier;
}
}
}
public class Random implements java.io.Serializable {
static final long serialVersionUID = 3905348978240129619L;
private long seed;
private final static long multiplier = 0x5DEECE66DL;
private final static long addend = 0xBL;
private final static long mask = (1L << 48) - 1;
public Random() { this(System.currentTimeMillis()); }
public Random(long seed) {
setSeed(seed);
} synchronized public void setSeed(long seed) {
this.seed = (seed ^ multiplier) & mask;
haveNextNextGaussian = false;
} synchronized protected int next(int bits) {
long nextseed = (seed * multiplier + addend) & mask;
seed = nextseed;
return (int)(nextseed >>> (48 - bits));
} private static final int BITS_PER_BYTE = 8;
private static final int BYTES_PER_INT = 4; public void nextBytes(byte[] bytes) {
int numRequested = bytes.length; int numGot = 0, rnd = 0; while (true) {
for (int i = 0; i < BYTES_PER_INT; i++) {
if (numGot == numRequested)
return; rnd = (i==0 ? next(BITS_PER_BYTE * BYTES_PER_INT)
: rnd >> BITS_PER_BYTE);
bytes[numGot++] = (byte)rnd;
}
}
} public int nextInt() { return next(32); } public int nextInt(int n) {
if (n<=0)
throw new IllegalArgumentException("n must be positive"); if ((n & -n) == n) // i.e., n is a power of 2
return (int)((n * (long)next(31)) >> 31); int bits, val;
do {
bits = next(31);
val = bits % n;
} while(bits - val + (n-1) < 0);
return val;
} public long nextLong() {
return ((long)(next(32)) << 32) + next(32);
} public boolean nextBoolean() {return next(1) != 0;} public float nextFloat() {
int i = next(24);
return i / ((float)(1 << 24));
} public double nextDouble() {
long l = ((long)(next(26)) << 27) + next(27);
return l / (double)(1L << 53);
} private double nextNextGaussian;
private boolean haveNextNextGaussian = false; synchronized public double nextGaussian() {
if (haveNextNextGaussian) {
haveNextNextGaussian = false;
return nextNextGaussian;
} else {
double v1, v2, s;
do {
v1 = 2 * nextDouble() - 1; // between -1 and 1
v2 = 2 * nextDouble() - 1; // between -1 and 1
s = v1 * v1 + v2 * v2;
} while (s >= 1 || s == 0);
double multiplier = Math.sqrt(-2 * Math.log(s)/s);
nextNextGaussian = v2 * multiplier;
haveNextNextGaussian = true;
return v1 * multiplier;
}
}
}