How do I use multi-catch statement?

The multi-catch is a language enhancement feature introduces in the Java 7. This allow us to use a single catch block to handle multiple exceptions. Each exception is separated by the pipe symbol (|).

Using the multi-catch simplify our exception handling and also reduce code duplicates in the catch block. Let’s see an example below:

package org.kodejava.example.lang;

import java.io.IOException;
import java.sql.SQLException;

public class MultiCatchDemo {
    public static void main(String[] args) {
        MultiCatchDemo demo = new MultiCatchDemo();
        try {
            demo.callA();
            demo.callB();
            demo.callC();
        } catch (IOException | SQLException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    private void callA() throws IOException {
        throw new IOException("IOException");
    }

    private void callB() throws SQLException {
        throw new SQLException("SQLException");
    }

    private void callC() throws ClassNotFoundException {
        throw new ClassNotFoundException("ClassNotFoundException");
    }
}

How do I create custom exception class?

You can define your own exception class for your application specific purposes. The exception class is created by extending the java.lang.Exception class for checked exception or java.lang.RuntimeException for unchecked exception. By creating your own Exception classes, you could identify the problem more precisely.

package org.kodejava.example.fundamental;

public class CustomExceptionExample {
    public static void main(String[] args) {
        int x = 1, y = 0;

        try {
            int z = CustomExceptionExample.divide(x, y);
            System.out.println("z = " + z);
        } catch (DivideByZeroException e) {
            e.printStackTrace();
        }
    }

    public static int divide(int x, int y) throws DivideByZeroException {
        try {
            return (x / y);
        } catch (ArithmeticException e) {
            String m = x + " / " + y + ", trying to divide by zero";
            throw new DivideByZeroException(m, e);
        }
    }
}
class DivideByZeroException extends Exception {
    DivideByZeroException() {
    }

    DivideByZeroException(String message) {
        super(message);
    }

    DivideByZeroException(String message, Throwable cause) {
        super(message, cause);
    }
}