Recover in Logo

Java provides a mechanism to handle exceptions, which is similar to the concept of recovering from panics in other languages. This is done using try-catch blocks.

import java.util.function.Supplier;

public class RecoverExample {

    // This method throws an exception
    public static void mayThrow() {
        throw new RuntimeException("a problem");
    }

    public static void main(String[] args) {
        // We use a lambda function to wrap the potentially throwing code
        Supplier<Void> tryBlock = () -> {
            mayThrow();
            System.out.println("After mayThrow()");
            return null;
        };

        try {
            tryBlock.get();
        } catch (Exception e) {
            // This is equivalent to the recover functionality
            System.out.println("Recovered. Error:\n " + e.getMessage());
        }
    }
}

In Java, we use exception handling to achieve similar functionality to recover. The try-catch block is used to catch and handle exceptions, which is analogous to recovering from panics.

The mayThrow() method simulates a function that might cause an problem by throwing a RuntimeException.

In the main method, we wrap the potentially throwing code in a Supplier lambda. This is not strictly necessary, but it helps to mimic the structure of the original example where the panicking code is in a separate function.

The try block contains the code that might throw an exception. If an exception is thrown, it’s caught in the catch block. This is similar to how recover works in other languages.

If we run this program, we’ll see:

$ javac RecoverExample.java
$ java RecoverExample
Recovered. Error:
 a problem

The code after mayThrow() in the try block doesn’t execute because an exception is thrown. Instead, execution continues in the catch block, which prints the error message.

This demonstrates how Java’s exception handling can be used to gracefully handle and recover from errors, allowing a program to continue execution rather than terminating abruptly.