get Random Number in range - Java java.util

Java examples for java.util:Random Int

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Description

get Random Number in range

Demo Code


//package com.java2s;

import java.util.Random;

public class Main {

    public static Integer getRandomNum(int max, int min) {
        Random random = new Random();
        int result = random.nextInt(max) % (max - min + 1) + min;
        return result;
    }/*from  ww  w . ja v  a2  s. co m*/

    public static String getRandomNum(String prefix, int length) {
        StringBuilder builder = new StringBuilder();
        builder.append(prefix).append(getRandomNum(length));
        return builder.toString();
    }

    public static String getRandomNum(int length) {
        Random random = new Random();
        StringBuffer buffer = new StringBuffer();
        String len = prefixZero(1, length);
        int strLen = len.length();
        int num = strLen % 10 == 0 ? strLen / 10 : (strLen / 10) + 1;
        int mode = strLen % 10;
        if (length < 10) {
            int randomNum = random.nextInt(Integer.parseInt(prefixZero(
                    mode, mode)));
            int baseNum = Integer.parseInt(prefixZero(1, mode));
            buffer.append(randomNum + baseNum);
        } else {
            for (int i = 1; i <= num; i++) {
                if (i < num) {
                    buffer.append(random.nextInt(1000000000) + 1000000000);
                } else if (i == num && mode != 0) {
                    int randomNum = random.nextInt(Integer
                            .parseInt(prefixZero(mode, mode)));
                    int baseNum = Integer.parseInt(prefixZero(1, mode));
                    buffer.append(randomNum + baseNum);
                } else if (i == num && mode == 0) {
                    buffer.append(random.nextInt(1000000000) + 1000000000);
                }
            }
        }
        return buffer.toString();
    }

    public static String prefixZero(int prefix, int length) {
        return new StringBuilder()
                .append(prefix)
                .append(String.format(
                        "%0$0"
                                + (length - new Integer(prefix).toString()
                                        .length()) + "d", 0)).toString();
    }
}

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