Java Tips - Use StringUtils to Compare Strings

 

Scenario

Wrapper classes come with a bunch of methods which are very easy to use in practice. When we literally assign a value to this kind of objects, these methods work well in a convenient and intuitive way. But if they take values from a SQL select result, they will become nullable objects when their corresponding fields in the database table are nulls. This causes a NullPointerException exception during runtime.

StringUtils can be used as an alternative to avoid the potential defect.

Example

 

import org.apache.commons.lang3.StringUtils;

public class App 

{

    public static void main( String[] args )

    {

    String strA = "abcd";

    String strB = "ABcd";

    String strC = "abcd";

    String strNull = null;

   

    System.out.println( strB.replace("AB", "ab").equals(strA));

   

    try {

    strNull.equals(strA);

    } catch (NullPointerException ex) {

    System.out.println(ex);

    }

   

        System.out.println( StringUtils.equals(strA, strB) );

        System.out.println( StringUtils.equals(strA, strC) );

        System.out.println( StringUtils.equals(strNull, strA) );

    }

}

Output:

true

java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because "strNull" is null

false

true

false