Package org.djutils.exceptions

Class Try

java.lang.Object
org.djutils.exceptions.Try
public final class Try extends Object
The Try class has a number of static methods that make it easy to try-catch an exception for any Throwable class, including the standard Java exceptions and exceptions from libraries that are used in the project. Instead of: 
 FileInputStream fis;
 try
 {
     fis = new FileInputStream(fileString);
 }
 catch (FileNotFoundException exception)
 {
     throw new IllegalArgumentException("File " + fileString + " is not a valid file.", exception);
 }
 try
 {
     fis.close();
 }
 catch (IOException exception)
 {
     throw new RuntimeException("Could not close the file.", exception);
 }
we can write: 
 FileInputStream fis = Try.assign(() -> new FileInputStream(fileString), IllegalArgumentException.class,
         "File %s is not a valid file.", fileString);
 Try.execute(() -> fis.close(), "Could not close the file.");
The exception message can be formatted with additional arguments, such that the overhead of building the exception message only occurs if the exception condition is met. For each method there is a version without Throwable class, in which case a RuntimeException will be thrown.

Try is not suitable for try-with-resource statements.

Try also has a few methods to aid JUNIT tests: testFail(...) and testNotFail(...).

Copyright (c) 2016-2024 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See for project information https://djutils.org. The DJUTILS project is distributed under a three-clause BSD-style license, which can be found at https://djutils.org/docs/license.html.

Author:
Alexander Verbraeck, Peter Knoppers, Wouter Schakel

  • Method Details

    • assign

      public static <V> V assign(Try.Assignment<V> assignment, String message) throws RuntimeException
      Tries to return a value to assign. Will throw a RuntimeException if the try fails.
      Type Parameters:
      V - value type
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      message - String; the message to use in the throwable
      Returns:
      V; value to assign
      Throws:
      RuntimeException - on failed Try

    • assign

      public static <V> V assign(Try.Assignment<V> assignment, String message, Object arg) throws RuntimeException
      Tries to return a value to assign. Will throw a RuntimeException if the try fails.
      Type Parameters:
      V - value type
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      message - String; the message to use in the throwable, with formatting identifier
      arg - Object; value to use for the formatting identifier
      Returns:
      V; value to assign
      Throws:
      RuntimeException - on failed Try

    • assign

      public static <V> V assign(Try.Assignment<V> assignment, String message, Object arg1, Object arg2) throws RuntimeException
      Tries to return a value to assign. Will throw a RuntimeException if the try fails.
      Type Parameters:
      V - value type
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      Returns:
      V; value to assign
      Throws:
      RuntimeException - on failed Try

    • assign

      public static <V> V assign(Try.Assignment<V> assignment, String message, Object arg1, Object arg2, Object arg3) throws RuntimeException
      Tries to return a value to assign. Will throw a RuntimeException if the try fails.
      Type Parameters:
      V - value type
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      arg3 - Object; 3rd value to use for the formatting identifiers
      Returns:
      V; value to assign
      Throws:
      RuntimeException - on failed Try

    • assign

      public static <V> V assign(Try.Assignment<V> assignment, String message, Object arg1, Object arg2, Object arg3, Object... args) throws RuntimeException
      Tries to return a value to assign. Will throw a RuntimeException if the try fails.
      Type Parameters:
      V - value type
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      arg3 - Object; 3rd value to use for the formatting identifiers
      args - Object...; potential 4th and further values to use for the formatting identifiers
      Returns:
      V; value to assign
      Throws:
      RuntimeException - on failed Try

    • assign

      public static <V, T extends Throwable> V assign(Try.Assignment<V> assignment, Class<T> throwableClass, String message) throws T
      Tries to return a value to assign. Will throw a specified Throwable if the try fails.
      Type Parameters:
      V - value type
      T - throwable type
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      throwableClass - Class<T>; class of the throwable to throw
      message - String; the message to use in the throwable
      Returns:
      V; value to assign
      Throws:
      T - throwable on failed Try

    • assign

      public static <V, T extends Throwable> V assign(Try.Assignment<V> assignment, Class<T> throwableClass, String message, Object arg) throws T
      Tries to return a value to assign. Will throw a specified Throwable if the try fails.
      Type Parameters:
      V - value type
      T - throwable type
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      throwableClass - Class<T>; class of the throwable to throw
      message - String; the message to use in the throwable, with formatting identifier
      arg - Object; value to use for the formatting identifier
      Returns:
      V; value to assign
      Throws:
      T - throwable on failed Try

    • assign

      public static <V, T extends Throwable> V assign(Try.Assignment<V> assignment, Class<T> throwableClass, String message, Object arg1, Object arg2) throws T
      Tries to return a value to assign. Will throw a specified Throwable if the try fails.
      Type Parameters:
      V - value type
      T - throwable type
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      throwableClass - Class<T>; class of the throwable to throw
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      Returns:
      V; value to assign
      Throws:
      T - throwable on failed Try

    • assign

      public static <V, T extends Throwable> V assign(Try.Assignment<V> assignment, Class<T> throwableClass, String message, Object arg1, Object arg2, Object arg3) throws T
      Tries to return a value to assign. Will throw a specified Throwable if the try fails.
      Type Parameters:
      V - value type
      T - throwable type
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      throwableClass - Class<T>; class of the throwable to throw
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      arg3 - Object; 3rd value to use for the formatting identifiers
      Returns:
      V; value to assign
      Throws:
      T - throwable on failed Try

    • assign

      public static <V, T extends Throwable> V assign(Try.Assignment<V> assignment, Class<T> throwableClass, String message, Object arg1, Object arg2, Object arg3, Object... args) throws T
      Tries to return a value to assign. Will throw a specified Throwable if the try fails.
      Type Parameters:
      V - value type
      T - throwable type
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      throwableClass - Class<T>; class of the throwable to throw
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      arg3 - Object; 3rd value to use for the formatting identifiers
      args - Object...; potential 4th and further values to use for the formatting identifiers
      Returns:
      V; value to assign
      Throws:
      T - throwable on failed Try

    • execute

      public static void execute(Try.Execution execution, String message) throws RuntimeException
      Tries to execute. Will throw a RuntimeException if the try fails.
      Parameters:
      execution - Execution; functional interface to execute
      message - String; the message to use in the throwable
      Throws:
      RuntimeException - on failed Try

    • execute

      public static void execute(Try.Execution execution, String message, Object arg) throws RuntimeException
      Tries to execute. Will throw a RuntimeException if the try fails.
      Parameters:
      execution - Execution; functional interface to execute
      message - String; the message to use in the throwable, with formatting identifier
      arg - Object; value to use for the formatting identifier
      Throws:
      RuntimeException - on failed Try

    • execute

      public static void execute(Try.Execution execution, String message, Object arg1, Object arg2) throws RuntimeException
      Tries to execute. Will throw a RuntimeException if the try fails.
      Parameters:
      execution - Execution; functional interface to execute
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      Throws:
      RuntimeException - on failed Try

    • execute

      public static void execute(Try.Execution execution, String message, Object arg1, Object arg2, Object arg3) throws RuntimeException
      Tries to execute. Will throw a RuntimeException if the try fails.
      Parameters:
      execution - Execution; functional interface to execute
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      arg3 - Object; 3rd value to use for the formatting identifiers
      Throws:
      RuntimeException - on failed Try

    • execute

      public static void execute(Try.Execution execution, String message, Object arg1, Object arg2, Object arg3, Object... args) throws RuntimeException
      Tries to execute. Will throw a RuntimeException if the try fails.
      Parameters:
      execution - Execution; functional interface to execute
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      arg3 - Object; 3rd value to use for the formatting identifiers
      args - Object...; potential 4th and further values to use for the formatting identifiers
      Throws:
      RuntimeException - on failed Try

    • execute

      public static <T extends Throwable> void execute(Try.Execution execution, Class<T> throwableClass, String message) throws T
      Tries to execute. Will throw a specified Throwable if the try fails.
      Type Parameters:
      T - throwable type
      Parameters:
      execution - Execution; functional interface to execute
      throwableClass - Class<T>; class of the throwable to throw
      message - String; the message to use in the throwable
      Throws:
      T - throwable on failed Try

    • execute

      public static <T extends Throwable> void execute(Try.Execution execution, Class<T> throwableClass, String message, Object arg) throws T
      Tries to execute. Will throw a specified Throwable if the try fails.
      Type Parameters:
      T - throwable type
      Parameters:
      execution - Execution; functional interface to execute
      throwableClass - Class<T>; class of the throwable to throw
      message - String; the message to use in the throwable, with formatting identifier
      arg - Object; value to use for the formatting identifier
      Throws:
      T - throwable on failed Try

    • execute

      public static <T extends Throwable> void execute(Try.Execution execution, Class<T> throwableClass, String message, Object arg1, Object arg2) throws T
      Tries to execute. Will throw a specified Throwable if the try fails.
      Type Parameters:
      T - throwable type
      Parameters:
      execution - Execution; functional interface to execute
      throwableClass - Class<T>; class of the throwable to throw
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      Throws:
      T - throwable on failed Try

    • execute

      public static <T extends Throwable> void execute(Try.Execution execution, Class<T> throwableClass, String message, Object arg1, Object arg2, Object arg3) throws T
      Tries to execute. Will throw a specified Throwable if the try fails.
      Type Parameters:
      T - throwable type
      Parameters:
      execution - Execution; functional interface to execute
      throwableClass - Class<T>; class of the throwable to throw
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      arg3 - Object; 3rd value to use for the formatting identifiers
      Throws:
      T - throwable on failed Try

    • execute

      public static <T extends Throwable> void execute(Try.Execution execution, Class<T> throwableClass, String message, Object arg1, Object arg2, Object arg3, Object... args) throws T
      Tries to execute. Will throw a specified Throwable if the try fails.
      Type Parameters:
      T - throwable type
      Parameters:
      execution - Execution; functional interface to execute
      throwableClass - Class<T>; class of the throwable to throw
      message - String; the message to use in the throwable, with formatting identifiers
      arg1 - Object; 1st value to use for the formatting identifiers
      arg2 - Object; 2nd value to use for the formatting identifiers
      arg3 - Object; 3rd value to use for the formatting identifiers
      args - Object...; potential 4th and further values to use for the formatting identifiers
      Throws:
      T - throwable on failed Try

    • testFail

      public static <V> V testFail(Try.Assignment<V> assignment)
      Method for unit tests to test if an expected exception is thrown on an assignment. This method does not provide an explanation, and it is not checking for a specific type of exception to be thrown. The testFail() method throws an AssertionError when the assignment does not throw any exception. A way to use the method is, for instance: 
       
   Try.testFail(() -> methodFailsOnNull(null));
      or 
      
   Try.testFail(new Try.Assignment<Double>()
   {
       @Override
       public Double assign() throws Throwable
       {
           return methodFailsOnNull(null);
       }
   });
      Type Parameters:
      V - value type, which is the return type of the assignment
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      Returns:
      V; assigned value
      Throws:
      AssertionError - when the assignment fails to throw an exception

    • testFail

      public static <V> V testFail(Try.Assignment<V> assignment, String message)
      Method for unit tests to test if an expected exception is thrown on an assignment. This method provides an explanation message, but it is not checking for a specific type of exception to be thrown. The testFail() method throws an AssertionError when the assignment does not throw an exception. A way to use the method is, for instance: 
       
   Try.testFail(() -> methodFailsOnNull(null), "call should have thrown an NPE");
      or 
      
   Try.testFail(new Try.Assignment<Double>()
   {
       @Override
       public Double assign() throws Throwable
       {
           return methodFailsOnNull(null);
       }
   }, "call should have thrown an NPE");
      Type Parameters:
      V - value type, which is the return type of the assignment
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      message - String; message to use in the AssertionError when the assignment succeeds
      Returns:
      V; assigned value
      Throws:
      AssertionError - when the assignment fails to throw an exception

    • testFail

      public static <V, T extends Throwable> V testFail(Try.Assignment<V> assignment, Class<T> expectedThrowableClass)
      Method for unit tests to test if an expected exception is thrown on an assignment. This method does not provide an explanation, but it is checking for a specific type of exception to be thrown. The testFail() method throws an AssertionError when the assignment does not throw an exception, or when it throws a different exception than expectedThrowableClass. A way to use the method is, for instance: 
       
   Try.testFail(() -> methodFailsOnNull(null), NullPointerException.class);
      or 
      
   Try.testFail(new Try.Assignment<Double>()
   {
       @Override
       public Double assign() throws Throwable
       {
           return methodFailsOnNull(null);
       }
   }, NullPointerException.class);
      Type Parameters:
      V - value type, which is the return type of the assignment
      T - throwable type, which ensures that we provide a throwable class as the argument
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      expectedThrowableClass - Class<T>; the class of the exception we expect the assignment to throw
      Returns:
      V; assigned value
      Throws:
      AssertionError - when the assignment fails to throw an exception or the correct exception

    • testFail

      public static <V, T extends Throwable> V testFail(Try.Assignment<V> assignment, String message, Class<T> expectedThrowableClass)
      Method for unit tests to test if an expected exception is thrown on an assignment. This method provides an explanation message, and it is checking for a specific type of exception to be thrown. The testFail() method throws an AssertionError when the assignment does not throw an exception, or when it throws a different exception than expectedThrowableClass. A way to use the method is, for instance: 
       
   Try.testFail(() -> methodFailsOnNull(null), "call should have thrown an NPE", NullPointerException.class);
      or 
      
   Try.testFail(new Try.Assignment<Double>()
   {
       @Override
       public Double assign() throws Throwable
       {
           return methodFailsOnNull(null);
       }
   }, "call should have thrown an NPE", NullPointerException.class);
      Type Parameters:
      V - value type, which is the return type of the assignment
      T - throwable type, which ensures that we provide a throwable class as the argument
      Parameters:
      assignment - Assignment<V>; functional interface to assign value
      message - String; message to use in the AssertionError when the test fails
      expectedThrowableClass - Class<T>; the class of the exception we expect the assignment to throw
      Returns:
      V; assigned value

    • testFail

      public static void testFail(Try.Execution execution)
      Method for unit tests to test if an expected exception is thrown on code execution. This method does not provide an explanation message, nor is it checking for a specific type of exception to be thrown. The testFail() method throws an AssertionError when the execution does not throw an exception. A way to use the method is, for instance: 
       
   Try.testFail(() -> methodFailsOnNull(null));
      or 
      
   Try.testFail(new Try.Execution()
   {
       @Override
       public void execute() throws Throwable
       {
           methodFailsOnNull(null);
       }
   });
      Parameters:
      execution - Execution; functional interface to execute a method that does not need to return a value

    • testFail

      public static void testFail(Try.Execution execution, String message)
      Method for unit tests to test if an expected exception is thrown on code execution. This method provides an explanation message, but it is not checking for a specific type of exception to be thrown. The testFail() method throws an AssertionError when the execution does not throw an exception, or when it throws a different exception than expectedThrowableClass. A way to use the method is, for instance: 
       
   Try.testFail(() -> methodFailsOnNull(null), "call should have thrown an NPE");
      or 
      
   Try.testFail(new Try.Execution()
   {
       @Override
       public void execute() throws Throwable
       {
           methodFailsOnNull(null);
       }
   }, "call should have thrown an NPE");
      Parameters:
      execution - Execution; functional interface to execute a method that does not need to return a value
      message - String; message to use in the AssertionError when the test fails

    • testFail

      public static <T extends Throwable> void testFail(Try.Execution execution, Class<T> expectedThrowableClass)
      Method for unit tests to test if an expected exception is thrown on code execution. This method does not provide an explanation message, but it is checking for a specific type of exception to be thrown. The testFail() method throws an AssertionError when the execution does not throw an exception, or when it throws a different exception than expectedThrowableClass. A way to use the method is, for instance: 
       
   Try.testFail(() -> methodFailsOnNull(null), NullPointerException.class);
      or 
      
   Try.testFail(new Try.Execution()
   {
       @Override
       public void execute() throws Throwable
       {
           methodFailsOnNull(null);
       }
   }, NullPointerException.class);
      Type Parameters:
      T - throwable type, which ensures that we provide a throwable class as the argument
      Parameters:
      execution - Execution; functional interface to execute a method that does not need to return a value
      expectedThrowableClass - Class<T>; the class of the exception we expect the execution to throw

    • testFail

      public static <T extends Throwable> void testFail(Try.Execution execution, String message, Class<T> expectedThrowableClass)
      Method for unit tests to test if an expected exception is thrown on code execution. This method provides an explanation message, and it is checking for a specific type of exception to be thrown. The testFail() method throws an AssertionError when the execution does not throw an exception, or when it throws a different exception than expectedThrowableClass. A way to use the method is, for instance: 
       
   Try.testFail(() -> methodFailsOnNull(null), "call should have thrown an NPE", NullPointerException.class);
      or 
      
   Try.testFail(new Try.Execution()
   {
       @Override
       public void execute() throws Throwable
       {
           methodFailsOnNull(null);
       }
   }, "call should have thrown an NPE", NullPointerException.class);
      Type Parameters:
      T - throwable type, which ensures that we provide a throwable class as the argument
      Parameters:
      execution - Execution; functional interface to execute a method that does not need to return a value
      message - String; message to use in the AssertionError when the test fails
      expectedThrowableClass - Class<T>; the class of the exception we expect the execution to throw