java生成随机数字和字母组合

import java.util.Random;

public String getCharAndNumr(int length)
{
String val = "";

Random random = new Random();
for(int i = 0; i < length; i++)
{
String charOrNum = random.nextInt(2) % 2 == 0 ? "char" : "num"; // 输出字母还是数字

if("char".equalsIgnoreCase(charOrNum)) // 字符串
{
int choice = random.nextInt(2) % 2 == 0 ? 65 : 97; //取得大写字母还是小写字母
val += (char) (choice + random.nextInt(26));
}
else if("num".equalsIgnoreCase(charOrNum)) // 数字
{
val += String.valueOf(random.nextInt(10));
}
}

return val;
}