Java try-with-resources

try { // Some code that may generate exception }
catch(Exception ex) { //handle exception }
finally { //close any open resources etc. }
try (resource declaration) { 
// use of the resource
} catch (ExceptionType e1) {
// handle exception
}
import java.io.*;class Main {
public static void main(String[] args) {
String line;
try(BufferedReader br = new BufferedReader(new FileReader(“test.txt”))) {
while ((line = br.readLine()) != null) {
System.out.println(“Line =>”+line);
}
} catch (IOException e) {
System.out.println(“IOException in try block =>” + e.getMessage());
}
}
}
catch(IOException e) {
System.out.println("Thrown exception=>" + e.getMessage());
Throwable[] suppressedExceptions = e.getSuppressed();
for (int i=0; i<suppressedExceptions.length; i++) {
System.out.println("Suppressed exception=>" + suppressedExceptions[i]);
}
}
public User findByFirstName(String firstName){
User user =new User();
try (Connection connection = dataSource.getConnection()) {
PreparedStatement selectStatement = connection.prepareStatement("select * from users where first_name = ?");
selectStatement.setString(1, firstName);
ResultSet rs = selectStatement.executeQuery();
if (rs.next()) { user = extractUserFromResultSet(rs);}
}
catch (SQLException se) {
System.out.println(se.getMessage());
}

return user;
}
  1. finally block not required to close the resource
  2. . We can declare more than one resource in the try-with-resources statement by separating them with a semicolon ;
try ( Scanner scanner = new Scanner(new File(“testRead.txt”)); 
PrintWriter writer = new PrintWriter(new File(“testWrite.txt”))) {
while (scanner.hasNext()) {
writer.print(scanner.nextLine());
}
}
Scanner scanner = new Scanner(new File(“testRead.txt”));
try (scanner) {
// code
}

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System Administrator and Full stack web developer.

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Himanshu Pratap

Himanshu Pratap

System Administrator and Full stack web developer.

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