import java.util.Random;

public class GenerateRandomNumber {

 public static void main(String[] args) {

  System.out.println("生成的10為隨機數為：" + getCharAndNumr(10));
 }

 /**
  * java生成隨機數字和字母組合
  * @param length[生成隨機數的長度]
  * @return
  */
 public static String getCharAndNumr(int length) {
  String val = "";
  Random random = new Random();
  for (int i = 0; i < length; i++) {
   // 輸出字母還是數字
   String charOrNum = random.nextInt(2) % 2 == 0 ? "char" : "num";
   // 字符串
   if ("char".equalsIgnoreCase(charOrNum)) {
    // 取得大寫字母還是小寫字母
    int choice = random.nextInt(2) % 2 == 0 ? 65 : 97;
    val += (char) (choice + random.nextInt(26));
   } else if ("num".equalsIgnoreCase(charOrNum)) { // 數字
    val += String.valueOf(random.nextInt(10));
   }
  }
  return val;
 }

}