Basically, I have a form where people can enter stuff in, and there is one part where they input an email address. Sometimes, people just put in their name and don't put an actual email address. Sometimes they do not fill it out at all.
Is there any easy way to check to see if the string has an @ symbol in it and check to see if its Null?
Any help is appreciated
Use an AND boolean operator. str != null && str.contains("@")
We first check the string is not null, then check that it contains '@'. Note: The reason that the null check is first is so that we do not attempt to access the string if it is null.
String s = "[email protected]"; if(s!= null && !s.isEmpty() && s.contains("@") ) { System.out.println("ok"); } else System.out.println("ko"); } 
!s.isEmpty() is not needed. When s contains "@", it is never empty
The String class contains a contains method to check the @ symbol, and you can simply check for null with a != null call:
public static void main(String[] args) { String a = "should be false"; String b = "should be @true"; String c = null; System.out.println(checkString(a)); System.out.println(checkString(b)); System.out.println(checkString(c)); } static boolean checkString(String str) { return str != null && str.contains("@"); } Output:
false
true
false
Here is some really simple code to achieve this:
String ourString = "[email protected]"; if(/* Check if our string is null: */ ourString != null && /* Check if our string is empty: */ !ourString.isEmpty() && /* Check if our string contains "@": */ ourString.contains("@")) { System.out.println("String Fits the Requirements"); } else { System.out.println("String Does Not Fit the Requirements"); } For future reference, this is extremely broad for Stack Overflow, and you should try checking the javadoc before you make a post asking for the answer. For example, here is the javadoc for the String class: https://docs.oracle.com/javase/7/docs/api/java/lang/String.html
Javadocs provided by Oracle detail every method and attribute for all of the classes included in the standard java library. Here is a link to the javadoc homepage for Java 7. https://docs.oracle.com/javase/7/docs/api/overview-summary.html
I think use Optional is the best way to do this.
Codes like this:
String nullEmail = null; System.out.println(Optional.ofNullable(nullEmail).filter(s -> s.contains("@")).isPresent()); String rightEmail = "[email protected]"; System.out.println(Optional.ofNullable(rightEmail).filter(s -> s.contains("@")).isPresent()); String wrongEmail = "chentong"; System.out.println(Optional.ofNullable(wrongEmail).filter(s -> s.contains("@")).isPresent()); The output is:
false true false 
str != null && str.contains("@")str != null && str.contains("@")