MATERI STRUKTUR DATA (Lecture (SD-02) String & File Processing)

Characters

Characters are the fundamental of String & File

Character literals:

1. Letters: ‘a’, ‘b’, ..., ‘z’
2. Digits: ‘0’, ‘1’, ..., ‘z’
3. Punctuation: ‘,’ , ‘;’ , ‘.’ , ‘?’
4. Escaped Characters: 

• Single Quote : ‘\’’
• Double Quote : ‘\”’
• Blackslash : ‘\\’
• NewLine : ‘\n’
• Return : ‘\r’
• Tab : ‘\t’
• Backspace : ‘\b’

Character StandarizationRepresent as ASCII standart: American Standard Code of Information Excange

Defined by integer representations as byte 2^8

1. Uppercase: ‘A’=(char)65, ‘B’=(char)66, ..., ‘Z’=(char)90
2. Lowercase : ‘a’=(char)97, ‘b’=(char)98, ..., ‘z’=(char)122
3. Digits: ‘0’=(char)48, ‘1’=(char)2, ..., ‘9’=(char)57
4. Punctuation: ‘ ’=(char)32, ‘!’=(char)33
5. Escaped: ‘\n’=(char)10, ‘\r’=(char)33

String to Char

public static void main(String[] args) {

        char[] helloArray = { 'h', 'e', 'l', 'l', 'o', '.' };

        String helloString = new String(helloArray);

        System.out.println(helloString);

     System.out.println(helloString.charAt(0));

    }

Byte to Char

public static void main(String[] args) {

  System.out.println((char)65);

System.out.println((byte)'A');

String s = "hello \n world !!";

System.out.println(s);

System.out.println(s.length());

    }

String Concatenation &Substring

public static void main(String[] args) {

String h = "hello";

String w = "world";

System.out.println(h.concat(w)); 

        String s = h+w;

        String sub = s.substring(0, 5);

        System.out.println(sub);

    }

String Instance Methode

Java Methode for processing String:

1. Replace: replace, replaceAll
2. Split: split, token, substring
3. Case converting : upperCase, lowerCase

String replace

public static void main(String[] args) {

     String s = "I say, \t Welcome \n in Java Worlds \n My Friends";

       System.out.println(s);

       System.out.println(s.replace('s','S'));

       System.out.println(s.replaceAll("[\t\n]",""));

    }

String Split

String can be split use character splitter inside,

public static void main(String[] args) {

     String sentence = "Hello World";

        String[] words = sentence.split(" ");

        System.out.println(words[0]);

        System.out.println(words[0].charAt(0));    

}

String Token

public Map tokens(String str){

        HashMap result = new HashMap();

        String key;

        String value;

        StringTokenizer tokenizer = new StringTokenizer(str, " ");

        while (tokenizer.hasMoreTokens()) {

            String token = tokenizer.nextToken();

            int index = token.indexOf(':');

            key = token.substring(0, index);

            value = token.substring(index + 1);

            result.put(key,value); 

    }

        return result;

    }

String Token

public static void main(String[] args) {

        // test tokenize

        StringToken st= new StringToken();

        Map s = st.tokens("aku:mahasiswa kuliah:universitasTrunojoyo");

        System.out.println(s);

        Object status = s.get("aku");

        System.out.println(status);

        Object kampus = s.get("kuliah");

        System.out.println(kampus);

}

File Processing

Java IO and NIO are primary packages for file stream processing.

As Default methodes for read and write files only work for plain text, also for file which have decoding extention such as: pdf, doc, docx, ppt, ... etc, we can use others properietary java components such as: pdfbox(for pdf), apachePOI(for microsoft office, open office), etc.

File Processing - read file

 public String readFile(String fileInput){        

        String s="";

try{

            File f = new File(fileInput);

            FileInputStream in = new FileInputStream(f);

    int j = (int)f.length();

            char[] ch = new char[j];

            for(int i=0; i

                ch[i]=(char)in.read();

            }

            s = String.copyValueOf(ch);

        }

        catch(Exception e){

            System.out.println(e.toString());

        }        

        return s;

    }

File Processing - copy file

public void copyfile(String fs, String fd) throws IOException{

try{

            File f1 = new File(fs);

            File f2 = new File(fd);

            if(f2!=null){

                f2.delete();

            }

            InputStream in = new FileInputStream(f1);

            OutputStream out = new FileOutputStream(f2);

            byte[] buf = new byte[1024];

            int len;

            while ((len = in.read(buf)) > 0){

            out.write(buf, 0, len);

            }

                in.close();

                out.close();

            System.out.println("File "+fs+" is copied to:"+ fd);

            }

       catch(FileNotFoundException ex){

        System.out.println(ex.getMessage() + " in the specified directory.");

}

    }

File Processing

public static void main(String[] args) {

// copy file

       Filerw f = new Filerw();

       try{

       f.copyfile("F:\\Teks.docx", "F:\\CopyOfTeks.docx");

       }

       catch(IOException e){

           System.out.println("error to copy file");

       }

// read file

      String s = f.readFile("F:\\jurnal.txt");

       System.out.print(s);

    }

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