com.jgoodies.common.base

Class Preconditions

java.lang.Object

com.jgoodies.common.base.Preconditions

public final class Preconditions
extends java.lang.Object

Reduces the code necessary to check preconditions on method state and parameters.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	Preconditions()

Method Summary

Modifier and Type	Method and Description
static void	checkArgument(boolean expression, java.lang.String message) Checks the truth of the given expression and throws a customized IllegalArgumentException if it is false.
static void	checkArgument(boolean expression, java.lang.String messageFormat, java.lang.Object... messageArgs) Checks the truth of the given expression and throws a customized IllegalArgumentException if it is false.
static java.lang.String	checkNotBlank(java.lang.String str, java.lang.String message) Checks that the given string is not blank and throws a customized NullPointerException if it is null, and a customized IllegalArgumentException if it is empty or whitespace.
static java.lang.String	checkNotBlank(java.lang.String str, java.lang.String messageFormat, java.lang.Object... messageArgs) Checks that the given string is not blank and throws a customized NullPointerException if it is null, and a customized IllegalArgumentException if it is empty or whitespace.
static <T> T	checkNotNull(T reference, java.lang.String message) Checks that the given object reference is not null and throws a customized NullPointerException if it is.
static <T> T	checkNotNull(T reference, java.lang.String messageFormat, java.lang.Object... messageArgs) Checks that the given object reference is not null and throws a customized NullPointerException if it is.
static void	checkState(boolean expression, java.lang.String message) Checks the truth of the given expression and throws a customized IllegalStateException if it is false.
static void	checkState(boolean expression, java.lang.String messageFormat, java.lang.Object... messageArgs) Checks the truth of the given expression and throws a customized IllegalStateException if it is false.
(package private) static java.lang.String	format(java.lang.String messageFormat, java.lang.Object... messageArgs)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Preconditions

private Preconditions()

Method Detail

checkArgument

public static void checkArgument(boolean expression,
                                 java.lang.String message)

Checks the truth of the given expression and throws a customized IllegalArgumentException if it is false. Intended for doing parameter validation in methods and constructors, e.g.:

 public void foo(int count) {
    Preconditions.checkArgument(count > 0, "count must be positive.");
 }
 

Parameters:

expression - the precondition to check involving one ore more parameters to the calling method or constructor

message - the detail message to be used in the event that an exception is thrown

Throws:

java.lang.IllegalArgumentException - if expression is false

checkArgument

public static void checkArgument(boolean expression,
                                 java.lang.String messageFormat,
                                 java.lang.Object... messageArgs)

Checks the truth of the given expression and throws a customized IllegalArgumentException if it is false. Intended for doing parameter validation in methods and constructors, e.g.:

 public void foo(int count) {
    Preconditions.checkArgument(count > 0, "count must be positive: %s.", count);
 }
 

Parameters:

expression - the precondition to check involving one ore more parameters to the calling method or constructor

messageFormat - a format string for the detail message to be used in the event that an exception is thrown.

messageArgs - the arguments referenced by the format specifiers in the messageFormat

Throws:

java.lang.IllegalArgumentException - if expression is false

checkNotNull

public static <T> T checkNotNull(T reference,
                                 java.lang.String message)

Checks that the given object reference is not null and throws a customized NullPointerException if it is. Intended for doing parameter validation in methods and constructors, e.g.:

 public void foo(Bar bar, Baz baz) {
      this.bar = Preconditions.checkNotNull(bar, "bar must not be null.");
      Preconditions.checkNotBull(baz, "baz must not be null.");
 }
 

Type Parameters:

T - the type of the reference

Parameters:

reference - the object reference to check for being null

message - the detail message to be used in the event that an exception is thrown

Returns:

reference if not null

Throws:

java.lang.NullPointerException - if reference is null

checkNotNull

public static <T> T checkNotNull(T reference,
                                 java.lang.String messageFormat,
                                 java.lang.Object... messageArgs)

Checks that the given object reference is not null and throws a customized NullPointerException if it is. Intended for doing parameter validation in methods and constructors, e.g.:

 public void foo(Bar bar, Baz baz) {
      this.bar = Preconditions.checkNotNull(bar, "bar must not be null.");
      Preconditions.checkNotBull(baz, "The %s must not be null.", "baz");
 }
 

Type Parameters:

T - the type of the reference

Parameters:

reference - the object reference to check for being null

messageFormat - a format string for the detail message to be used in the event that an exception is thrown.

messageArgs - the arguments referenced by the format specifiers in the messageFormat

Returns:

reference if not null

Throws:

java.lang.NullPointerException - if reference is null

checkState

public static void checkState(boolean expression,
                              java.lang.String message)

Checks the truth of the given expression and throws a customized IllegalStateException if it is false. Intended for doing validation in methods involving the state of the calling instance, but not involving parameters of the calling method, e.g.:

 public void unlock() {
    Preconditions.checkState(locked, "Must be locked to be unlocked.");
 }
 

Parameters:

expression - the precondition to check involving the state of the calling instance

message - the detail message to be used in the event that an exception is thrown

Throws:

java.lang.IllegalStateException - if expression is false

checkState

public static void checkState(boolean expression,
                              java.lang.String messageFormat,
                              java.lang.Object... messageArgs)

Checks the truth of the given expression and throws a customized IllegalStateException if it is false. Intended for doing validation in methods involving the state of the calling instance, but not involving parameters of the calling method, e.g.:

 public void unlock() {
    Preconditions.checkState(locked,
        "Must be locked to be unlocked. Most recent lock: %s",
        mostRecentLock);
 }
 

Parameters:

expression - the precondition to check involving the state of the calling instance

messageFormat - a format string for the detail message to be used in the event that an exception is thrown.

messageArgs - the arguments referenced by the format specifiers in the messageFormat

Throws:

java.lang.IllegalStateException - if expression is false

checkNotBlank

public static java.lang.String checkNotBlank(java.lang.String str,
                                             java.lang.String message)

Checks that the given string is not blank and throws a customized NullPointerException if it is null, and a customized IllegalArgumentException if it is empty or whitespace. Intended for doing parameter validation in methods and constructors, e.g.:

 public void foo(String text) {
      checkNotBlank(text, "The text must not be null, empty or whitespace.");
 }
 

Parameters:

str - the string to check for being blank

message - the detail message to be used in the event that an exception is thrown

Returns:

str if not null

Throws:

java.lang.NullPointerException - if str is null

java.lang.IllegalArgumentException - if str is empty or whitespace

checkNotBlank

public static java.lang.String checkNotBlank(java.lang.String str,
                                             java.lang.String messageFormat,
                                             java.lang.Object... messageArgs)

Checks that the given string is not blank and throws a customized NullPointerException if it is null, and a customized IllegalArgumentException if it is empty or whitespace. Intended for doing parameter validation in methods and constructors, e.g.:

 public void foo(String text, String id) {
      checkNotBlank(
          text,
          "The text for %s must not be null, empty or whitespace.",
          id);
 }
 

Parameters:

str - the string to check for being blank

messageFormat - a format string for the detail message to be used in the event that an exception is thrown.

messageArgs - the arguments referenced by the format specifiers in the messageFormat

Returns:

str if not null

Throws:

java.lang.NullPointerException - if str is null

java.lang.IllegalArgumentException - if str is empty or whitespace

format

static java.lang.String format(java.lang.String messageFormat,
                               java.lang.Object... messageArgs)