title: how to store number of second in variable in java
body: <p>I want to generate a token(validity in second) for 20 years. So total numbers of second in 20 years are: 631152000. Here is a token generation code:</p>
  
  <pre><code>    long tokenLifetInSecond=631152000;
      long expiryTime = System.currentTimeMillis();
      expiryTime += 1000L * tokenLifetimeInSecond;
  </code></pre>
  
  <p>So the result of expiryTime=2095766040489. Is using long is a safe as it can store 2 billion records ?</p>