package com.kartik.file.parse;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class ReadCVS {
public static void main(String[] args) throws FileNotFoundException,
IOException {
ReadCVS obj = new ReadCVS();
obj.run();
}
public void run() {
String csvFile = "D:\\SCC\\studentData.txt";
BufferedReader br = null;
String cvsSplitBy = "\\|";
List<Student> studentCourseList = new ArrayList<Student>();
try {
br = readFileMethod(csvFile, cvsSplitBy, studentCourseList);
Map<String, Student> items = processData(studentCourseList);
writeFileMethod(items);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
System.out.println("Done");
}
/**
*
* @param csvFile
* csvFile
* @param cvsSplitBy
* cvsSplitBy
* @param studentCourseList
* studentCourseList
* @return br.
* @throws FileNotFoundException
* FileNotFoundException
* @throws IOException
* IOException
*/
private BufferedReader readFileMethod(String csvFile, String cvsSplitBy,
List<Student> studentCourseList) throws FileNotFoundException,
IOException {
BufferedReader br;
String line;
br = new BufferedReader(new FileReader(csvFile));
while ((line = br.readLine()) != null) {
// use comma as separator
String[] student = line.split(cvsSplitBy);
Student stdnt = new Student();
stdnt.setId(Integer.parseInt(student[0]));
stdnt.setCourseName(student[1]);
stdnt.setMarks(Integer.parseInt(student[2]));
studentCourseList.add(stdnt);
}
return br;
}
/**
*
* @param items
* items
* @throws IOException
* IOException
*/
private void writeFileMethod(Map<String, Student> items) throws IOException {
File file = new File("D:\\SCC\\studentNewCreate.csv");
// if file doesnt exists, then create it
if (!file.exists()) {
file.createNewFile();
}
FileWriter fw = new FileWriter(file.getAbsoluteFile());
BufferedWriter bw = new BufferedWriter(fw);
for (Map.Entry<String, Student> entry : items.entrySet()) {
Student st = entry.getValue();
bw.write(st.getCourseName() + ": " + st.getMarks());
bw.newLine();
}
bw.close();
}
/**
*
* @param array
* array
* @return Map<String,Student>
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public static Map<String, Student> processData(List<Student> array) {
Map<String, Student> retVal = new HashMap<String, Student>();
Collections.sort(array, new Comparator() {
public int compare(Object obj1, Object obj2) {
Student e1 = (Student) obj1;
Student e2 = (Student) obj2;
Integer firstId = new Integer(String.valueOf(e1.getId()));
Integer secndId = new Integer(String.valueOf(e2.getId()));
int id = firstId.compareTo(secndId);
int name = e1.getCourseName().compareTo(e2.getCourseName());
if (id != 0) {
return id;
} else if (id == 0 && name != 0) {
return name;
}
return id;
}
});
int countDS = 0, countEng = 0, key = 1;
for (Student student : array) {
//Data Structures and English declare in Constant file
if (student.getCourseName().equalsIgnoreCase("Data Structures")
&& countDS == 0) {
retVal.put(String.valueOf(key), student);
key++;
countDS++;
}
if (student.getCourseName().equalsIgnoreCase("English")
&& countEng == 0) {
retVal.put(String.valueOf(key), student);
key++;
countEng++;
}
}
countDS = 0;
countEng = 0;
key = 1;
return retVal;
}
}
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class ReadCVS {
public static void main(String[] args) throws FileNotFoundException,
IOException {
ReadCVS obj = new ReadCVS();
obj.run();
}
public void run() {
String csvFile = "D:\\SCC\\studentData.txt";
BufferedReader br = null;
String cvsSplitBy = "\\|";
List<Student> studentCourseList = new ArrayList<Student>();
try {
br = readFileMethod(csvFile, cvsSplitBy, studentCourseList);
Map<String, Student> items = processData(studentCourseList);
writeFileMethod(items);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
System.out.println("Done");
}
/**
*
* @param csvFile
* csvFile
* @param cvsSplitBy
* cvsSplitBy
* @param studentCourseList
* studentCourseList
* @return br.
* @throws FileNotFoundException
* FileNotFoundException
* @throws IOException
* IOException
*/
private BufferedReader readFileMethod(String csvFile, String cvsSplitBy,
List<Student> studentCourseList) throws FileNotFoundException,
IOException {
BufferedReader br;
String line;
br = new BufferedReader(new FileReader(csvFile));
while ((line = br.readLine()) != null) {
// use comma as separator
String[] student = line.split(cvsSplitBy);
Student stdnt = new Student();
stdnt.setId(Integer.parseInt(student[0]));
stdnt.setCourseName(student[1]);
stdnt.setMarks(Integer.parseInt(student[2]));
studentCourseList.add(stdnt);
}
return br;
}
/**
*
* @param items
* items
* @throws IOException
* IOException
*/
private void writeFileMethod(Map<String, Student> items) throws IOException {
File file = new File("D:\\SCC\\studentNewCreate.csv");
// if file doesnt exists, then create it
if (!file.exists()) {
file.createNewFile();
}
FileWriter fw = new FileWriter(file.getAbsoluteFile());
BufferedWriter bw = new BufferedWriter(fw);
for (Map.Entry<String, Student> entry : items.entrySet()) {
Student st = entry.getValue();
bw.write(st.getCourseName() + ": " + st.getMarks());
bw.newLine();
}
bw.close();
}
/**
*
* @param array
* array
* @return Map<String,Student>
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public static Map<String, Student> processData(List<Student> array) {
Map<String, Student> retVal = new HashMap<String, Student>();
Collections.sort(array, new Comparator() {
public int compare(Object obj1, Object obj2) {
Student e1 = (Student) obj1;
Student e2 = (Student) obj2;
Integer firstId = new Integer(String.valueOf(e1.getId()));
Integer secndId = new Integer(String.valueOf(e2.getId()));
int id = firstId.compareTo(secndId);
int name = e1.getCourseName().compareTo(e2.getCourseName());
if (id != 0) {
return id;
} else if (id == 0 && name != 0) {
return name;
}
return id;
}
});
int countDS = 0, countEng = 0, key = 1;
for (Student student : array) {
//Data Structures and English declare in Constant file
if (student.getCourseName().equalsIgnoreCase("Data Structures")
&& countDS == 0) {
retVal.put(String.valueOf(key), student);
key++;
countDS++;
}
if (student.getCourseName().equalsIgnoreCase("English")
&& countEng == 0) {
retVal.put(String.valueOf(key), student);
key++;
countEng++;
}
}
countDS = 0;
countEng = 0;
key = 1;
return retVal;
}
}
Step 2>
package com.kartik.file.parse;
public class Student {
private int id;
private String courseName;
private int marks;
/**
* @return the id
*/
public int getId() {
return id;
}
/**
* @param id the id to set
*/
public void setId(int id) {
this.id = id;
}
/**
* @return the courseName
*/
public String getCourseName() {
return courseName;
}
/**
* @param courseName the courseName to set
*/
public void setCourseName(String courseName) {
this.courseName = courseName;
}
/**
* @return the marks
*/
public int getMarks() {
return marks;
}
/**
* @param marks the marks to set
*/
public void setMarks(int marks) {
this.marks = marks;
}
}
Step 3>
CSV file
..........................................
22,Data Structures,45
23,English,52
22,English,51
26,Data Structures,72
23,Data Structures,61
21,English,81
I am Kartik Chandra Mandal from Bangalore, India. Working as software engineer in Java technology. Have good knowledge of OWASP and CSRF in security for applications and it's implementation in Java technology.