regexDemo5.java

String str1 = new String("hello world");
String str2 = new String("world hello");
String str3 = new String("the world wryyyy");

String regex = "^(?!.*hello)";
Pattern p = Pattern.compile(regex);
System.out.println(p.matcher(str1).find()); // false
System.out.println(p.matcher(str2).find()); // false
System.out.println(p.matcher(str3).find()); // true