com.terheyden.valid.ConstructorValidations Maven / Gradle / Ivy
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package com.terheyden.valid;
import java.lang.reflect.Constructor;
/**
* Helper class just for validating constructor parameters.
* Package-protected, used solely by {@link Validations}.
*/
/* package */ final class ConstructorValidations {
private ConstructorValidations() {
// Private since this class shouldn't be instantiated.
}
/**
* Find and return the one constructor of a class, for validating its parameters.
* Check out the other {@code findConstructor()} methods for other ways of finding the right constructor.
*
* @throws IllegalStateException if more than one matching constructor is found
*/
/* package */ static Constructor findConstructor(Class classType) {
try {
Constructor[] constructors = classType.getDeclaredConstructors();
if (constructors.length == 0) {
throw new IllegalStateException("No constructors found in class '%s'."
.formatted(classType.getSimpleName()));
}
if (constructors.length > 1) {
throw new IllegalStateException(
"Ambiguous; more than one constructor found in class '%s'."
.formatted(classType.getSimpleName()));
}
// All constructors checked, only one match found, so return it.
return constructors[0];
} catch (SecurityException e) {
return ValidationUtils.throwUnchecked(e);
}
}
/**
* Find a single constructor of a class, for validating its parameters.
*
* This version finds a {@link Constructor} with the given name and unique parameter type.
* For example, if you had {@code MyClass(String, String)}, and
* @code MyClass(String, Integer)}, calling {@code findConstructor(MyClass.class, Integer.class)}
* would return the second constructor (because it is the version with an {@code Integer} parameter.
*
* Check out the other {@code findConstructor()} method for other ways of finding the right constructor.
*/
/* package */ static Constructor findConstructor(Class classType, Class anyParamType) {
try {
Constructor foundConstructor = null;
for (Constructor constructor : classType.getDeclaredConstructors()) {
Class[] constructorParameterTypes = constructor.getParameterTypes();
if (constructorParameterTypes.length == 0) {
// Looking for at least 1 param.
continue;
}
if (ValidationUtils.findParameterByType(constructorParameterTypes, anyParamType) == -1) {
// No param of the right type, keep looking.
continue;
}
// If more than one match, warn the user.
if (foundConstructor != null) {
throw new IllegalStateException(
"Ambiguous; more than one constructor found with parameter type '%s' in class '%s'."
.formatted(anyParamType.getName(), classType.getName()));
}
// It's the first match, save it.
foundConstructor = constructor;
}
if (foundConstructor == null) {
throw new IllegalStateException(
"No constructor found with parameter type '%s' in class '%s'."
.formatted(anyParamType.getName(), classType.getName()));
} else {
// All constructors checked, only one match found, so return it.
return foundConstructor;
}
} catch (SecurityException e) {
return ValidationUtils.throwUnchecked(e);
}
}
/**
* Find a single constructor of a class, for validating its parameters.
*
* This version finds a {@link Constructor} with the given name and the given number of parameters.
* For example, if you had {@code MyClass(String, String)}, and
* @code MyClass(String)}, calling {@code findConstructor(MyClass.class, 1)}
* would return the second constructor.
*
* Check out the other {@code findConstructor()} method for other ways of finding the right constructor.
*/
/* package */ static Constructor findConstructor(Class classType, int paramCount) {
try {
Constructor foundConstructor = null;
for (Constructor constructor : classType.getDeclaredConstructors()) {
if (constructor.getParameterTypes().length != paramCount) {
// Not the right number of params, keep looking.
continue;
}
// If more than one match, warn the user.
if (foundConstructor != null) {
throw new IllegalStateException(
"Ambiguous; more than one constructor found with %d parameters in class '%s'."
.formatted(paramCount, classType.getName()));
}
// It's the first match.
foundConstructor = constructor;
}
if (foundConstructor == null) {
throw new IllegalStateException(
"No constructor found with %d parameters in class '%s'."
.formatted(paramCount, classType.getName()));
} else {
// All constructors checked, only one match found, so return it.
return foundConstructor;
}
} catch (SecurityException e) {
return ValidationUtils.throwUnchecked(e);
}
}
}