public class Javaexcercise {
 
    public static int getLineCount(String text){
 
        return text.split("[\n|\r]").length;
    }
 
    public static void main(String a[]){
 
        String str = "line1\nline2\nline3\rline4";      
        int count = getLineCount(str);
        System.out.println("Total Line count: "+count);
    }
}

Result