Groovy Tip 3: How to Determine if an object is empty in an IF condition statement

In the Java language programming, the non null Judgment of object is an eternal topic. For example, we often need to judge a string as follows:

if(str!=null&&!str.equals(""))
　　{
　　　 ......
}

Typing such a statement really makes you sick, and sometimes you forget the "!" in the input "!str.equals" statement. Causes the code to have a logical error.

and agile Groovy language development does not require us to worry about such problems. The same judgment statement, we just need to enter the following code:

def str = null
　　if(str)
　　{
　　　 println"str is not null"
　　}
　　else
　　{
　　　 println'str is null'
}

The execution result of this statement segment is:

STR is NULL

As can be seen, the IF (str) Judgment statement is not executed when STR is null. You might ask, what happens when str = '?

def str = ''
　　if(str)
　　{
　　　 println"str is not null"
　　}
　　else
　　{
　　　 println'str is null'
}

The results of the execution are:

STR is NULL

In this way, we can rewrite the beginning of the Java code into the following code:

if(str)
　　{
　　　 ......
}

This is a lot simpler. Isn't it?