[JAVA] use contains function when checking whether JAVA Java string is included

When checking for Java string inclusion

ex)

String str = "contains test";

System.out.println( str.contains("contains") );  // true

System.out.println( str.contains("what") );  // false

System.out.println( str.contains("TEST") );  // false

System.out.println( str.contains("test") );  // true

😀

Thank you!!

감사합니다!!