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How to generate a random String in Java
I am wanting to generate a random string of 20 characters without using apache classes. I don't really care about whether is alphanumeric or not. Also, I am going to convert it to an array of bytes later FYI.
Thanks,
This question is related to
java
I'd use this approach:
String randomString(final int length) {
Random r = new Random(); // perhaps make it a class variable so you don't make a new one every time
StringBuilder sb = new StringBuilder();
for(int i = 0; i < length; i++) {
char c = (char)(r.nextInt((int)(Character.MAX_VALUE)));
sb.append(c);
}
return sb.toString();
}
If you want a byte[] you can do this:
byte[] randomByteString(final int length) {
Random r = new Random();
byte[] result = new byte[length];
for(int i = 0; i < length; i++) {
result[i] = r.nextByte();
}
return result;
}
Or you could do this
byte[] randomByteString(final int length) {
Random r = new Random();
StringBuilder sb = new StringBuilder();
for(int i = 0; i < length; i++) {
char c = (char)(r.nextInt((int)(Character.MAX_VALUE)));
sb.append(c);
}
return sb.toString().getBytes();
}
public String randomString(String chars, int length) {
Random rand = new Random();
StringBuilder buf = new StringBuilder();
for (int i=0; i<length; i++) {
buf.append(chars.charAt(rand.nextInt(chars.length())));
}
return buf.toString();
}
You may use the class java.util.Random with method
char c = (char)(rnd.nextInt(128-32))+32
20x to get Bytes, which you interpret as ASCII. If you're fine with ASCII.
32 is the offset, from where the characters are printable in general.
Source: Stackoverflow.com