字符串标记器和Scanner Java

Question

I have a large text file which I want to separate into different strings using the delimiter !- (Each string is multiple lines).

I then want to discard all the other strings that do not contain:

===========  ALL OBJECTS IN CLASS: FENESTRATIONSURFACE:DETAILED ===========

So far I've got this and its not outputting anything (it complies but no output to console).I'm new to programming and I'm not making much progress after researching this for sometime so any suggestions or pointers would be most appreciated thanks!

public class Main {
    public static void main(String[] args) throws FileNotFoundException {
        File file = new File("C:/Users/Anton/Pictures/1 x geotransform0.5m shading.txt");
        Scanner scan = new Scanner(file);
        while(scan.hasNextLine()){
            StringTokenizer st = new StringTokenizer(scan.nextLine(),"!-");
            if(st.equals("   ===========  ALL OBJECTS IN CLASS: FENESTRATIONSURFACE:DETAILED ===========")) {
                System.out.print(st);
            }
        }
        scan.close();
    }
}

Answer 1

You should consider reading the java doc page to StringTokenizer : http://docs.oracle.com/javase/7/docs/api/java/util/StringTokenizer.html

There two different problems in your code:

1. Because your desired strings are more than one line out of a file, you first have to add them up (into a String ) and then work with it via StringTokenizer to separate again.
2. You have to compare the StringTokenizer.nextToken() to your check String not the whole StringTokenizer . StringTokenizer.nextToken() then gives you the next String separated through !- .

The following code should work:

public class Main {
public static void main(String[] args) throws FileNotFoundException {
    File file = new File("C:/Users/Anton/Pictures/1 x geotransform0.5m shading.txt");
    Scanner scan = new Scanner(file);
    //Scanning
    //first scan the whole file into a string (because a sting can have more than one line)
    String temp = "";
    while(scan.hasNextLine()){
        temp = scan.nextLine();
    }
    //now add the string to tokeinzer
    StringTokenizer st = new StringTokenizer(temp,"!-");
    //now give output
    while(st.hasMoreTokens()){
    String temp2 = st.nextToken();
        if(temp2.equals("   ===========  ALL OBJECTS IN CLASS: FENESTRATIONSURFACE:DETAILED ===========")) {
            System.out.print(temp2);
        }
    }
    scan.close();
}
}
}

Answer 2

remove the if condition and add the below while condition

 while (st.hasMoreElements()) {
                        System.out.println(st.nextElement());
                    }

because stringtokenizer splits the text based on token. so your if never becomes true.

Answer 3

try this...........

while(scan.hasNextLine()){
                StringTokenizer st = new StringTokenizer(scan.nextLine(),"!-");
                while(st.hasMoreTokens()){
                    String stt = st.nextElement().toString();
                    if(stt.equals("===========  ALL OBJECTS IN CLASS: FENESTRATIONSURFACE:DETAILED ===========")) {
                        System.out.print(stt);
                    }
                }
            }

you comparing string with stringtokenizer object not value....