如何生成一個具有小數位的隨機數

I would like to generate random numbers between 1 & 10, with a decimal place of 1 
(e.g. 1.5, 9.4, 6.3, 2.9) 

I would like to generate random numbers between 1 & 10, with 2 decimal places 
(e.g. 1.51, 9.46, 6.32, 2.93) 

I would like to generate random numbers between 1 & 10, with 3 decimal places 

    (e.g. 1.512, 9.346, 6.329, 2.935)

一種解決方案是將一個隨機數生成器僅用於小數位，然後與數字連接。有沒有更簡單的方法來實現這一點？如何生成一個具有小數位的隨機數

來源

2010-11-10 user339108

嘗試java.util.Random – Sid 2010-11-10 10:46:05

雖然BigDecimal的解決方案更加靈活，這是一個使用int和double一個簡單的解決方案。此方法採用一個Random對象，小數點的上界和下界和一個號碼和返回一個相應格式的字符串：

/** 
* Generate a decimal string representation of a random number within the 
* supplied bounds. 
* 
* @param random 
*   the random object (if null, a new one will be created) 
* @param lowerBound 
*   the lower bound, inclusive 
* @param upperBound 
*   the upper bound, inclusive 
* @param decimalPlaces 
*   the decimal places of the result 
* @return the formatted string 
*/ 
public static String getRandomValue(final Random random, 
    final int lowerBound, 
    final int upperBound, 
    final int decimalPlaces){ 

    if(lowerBound < 0 || upperBound <= lowerBound || decimalPlaces < 0){ 
     throw new IllegalArgumentException("Put error message here"); 
    } 

    final double dbl = 
     ((random == null ? new Random() : random).nextDouble() // 
      * (upperBound - lowerBound)) 
      + lowerBound; 
    return String.format("%." + decimalPlaces + "f", dbl); 

}

測試代碼：

final Random rnd = new Random(); 

for(int decpl = 0; decpl < 3; decpl++){ 
    for(int low = 0; low < 2; low++){ 
     for(int high = low + 1; high < low + 3; high++){ 
      System.out.println("Random Value between " + low + " and " 
       + high + " with " + decpl + " decimal places:"); 
      System.out.println(getRandomValue(rnd, low, high, decpl)); 
     } 
    } 
}

輸出：

Random Value between 0 and 1 with 0 decimal places: 
0 
Random Value between 0 and 2 with 0 decimal places: 
1 
Random Value between 1 and 2 with 0 decimal places: 
1 
Random Value between 1 and 3 with 0 decimal places: 
3 
Random Value between 0 and 1 with 1 decimal places: 
0.6 
Random Value between 0 and 2 with 1 decimal places: 
1.5 
Random Value between 1 and 2 with 1 decimal places: 
1.1 
Random Value between 1 and 3 with 1 decimal places: 
1.9 
Random Value between 0 and 1 with 2 decimal places: 
0.52 
Random Value between 0 and 2 with 2 decimal places: 
0.82 
Random Value between 1 and 2 with 2 decimal places: 
1.75 
Random Value between 1 and 3 with 2 decimal places: 
1.10

來源

2010-11-10 10:32:37

與我發佈的簡單解決方案相比，有什麼優勢？ – christian 2010-11-10 11:07:05

它可以重複使用許多不同的參數。如果您一次使用此類功能，請按照您的方式進行。如果您多次使用它，請按照我的方式進行。 – 2010-11-10 11:15:16