net.neoremind.fountain.Preconditions Maven / Gradle / Ivy
package net.neoremind.fountain;
/**
* 前验工具类
*
* @author zhangxu
*/
class Preconditions {
private Preconditions() {
}
/**
* Ensures the truth of an expression involving one or more parameters to the calling method.
*
* @param expression a boolean expression
*
* @throws IllegalArgumentException if {@code expression} is false
*/
public static void checkArgument(boolean expression) {
if (!expression) {
throw new IllegalArgumentException();
}
}
/**
* Ensures the truth of an expression involving one or more parameters to the calling method.
*
* @param expression a boolean expression
* @param errorMessage the exception message to use if the check fails; will be converted to a string using
* {@link String#valueOf(Object)}
*
* @throws IllegalArgumentException if {@code expression} is false
*/
public static void checkArgument(boolean expression, Object errorMessage) {
if (!expression) {
throw new IllegalArgumentException(String.valueOf(errorMessage));
}
}
/**
* Ensures the truth of an expression involving one or more parameters to the calling method.
*
* @param expression a boolean expression
* @param errorMessageTemplate a template for the exception message should the check fail. The message is formed
* by replacing each
* {@code %s} placeholder in the template with an argument. These are matched by
* position - the first
* {@code %s} gets {@code errorMessageArgs[0]}, etc. Unmatched arguments will be
* appended to the
* formatted message in square braces. Unmatched placeholders will be left as-is.
* @param errorMessageArgs the arguments to be substituted into the message template. Arguments are converted
* to strings using
* {@link String#valueOf(Object)}.
*
* @throws IllegalArgumentException if {@code expression} is false
* @throws NullPointerException if the check fails and either {@code errorMessageTemplate} or {@code
* errorMessageArgs} is null (don't
* let this happen)
*/
public static void checkArgument(boolean expression, String errorMessageTemplate,
Object... errorMessageArgs) {
if (!expression) {
throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
}
}
/**
* Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters
* to the calling method.
*
* @param expression a boolean expression
*
* @throws IllegalStateException if {@code expression} is false
*/
public static void checkState(boolean expression) {
if (!expression) {
throw new IllegalStateException();
}
}
/**
* Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters
* to the calling method.
*
* @param expression a boolean expression
* @param errorMessage the exception message to use if the check fails; will be converted to a string using
* {@link String#valueOf(Object)}
*
* @throws IllegalStateException if {@code expression} is false
*/
public static void checkState(boolean expression, Object errorMessage) {
if (!expression) {
throw new IllegalStateException(String.valueOf(errorMessage));
}
}
/**
* Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters
* to the calling method.
*
* @param expression a boolean expression
* @param errorMessageTemplate a template for the exception message should the check fail. The message is formed
* by replacing each
* {@code %s} placeholder in the template with an argument. These are matched by
* position - the first
* {@code %s} gets {@code errorMessageArgs[0]}, etc. Unmatched arguments will be
* appended to the
* formatted message in square braces. Unmatched placeholders will be left as-is.
* @param errorMessageArgs the arguments to be substituted into the message template. Arguments are converted
* to strings using
* {@link String#valueOf(Object)}.
*
* @throws IllegalStateException if {@code expression} is false
* @throws NullPointerException if the check fails and either {@code errorMessageTemplate} or {@code
* errorMessageArgs} is null (don't
* let this happen)
*/
public static void checkState(boolean expression, String errorMessageTemplate,
Object... errorMessageArgs) {
if (!expression) {
throw new IllegalStateException(format(errorMessageTemplate, errorMessageArgs));
}
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
*
* @return the non-null reference that was validated
*
* @throws NullPointerException if {@code reference} is null
*/
public static T checkNotNull(T reference) {
if (reference == null) {
throw new NullPointerException();
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
* @param errorMessage the exception message to use if the check fails; will be converted to a string using
* {@link String#valueOf(Object)}
*
* @return the non-null reference that was validated
*
* @throws NullPointerException if {@code reference} is null
*/
public static T checkNotNull(T reference, Object errorMessage) {
if (reference == null) {
throw new NullPointerException(String.valueOf(errorMessage));
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
* @param errorMessageTemplate a template for the exception message should the check fail. The message is formed
* by replacing each
* {@code %s} placeholder in the template with an argument. These are matched by
* position - the first
* {@code %s} gets {@code errorMessageArgs[0]}, etc. Unmatched arguments will be
* appended to the
* formatted message in square braces. Unmatched placeholders will be left as-is.
* @param errorMessageArgs the arguments to be substituted into the message template. Arguments are converted
* to strings using
* {@link String#valueOf(Object)}.
*
* @return the non-null reference that was validated
*
* @throws NullPointerException if {@code reference} is null
*/
public static T checkNotNull(T reference, String errorMessageTemplate,
Object... errorMessageArgs) {
if (reference == null) {
// If either of these parameters is null, the right thing happens anyway
throw new NullPointerException(format(errorMessageTemplate, errorMessageArgs));
}
return reference;
}
/**
* Substitutes each {@code %s} in {@code template} with an argument. These are matched by position: the first
* {@code %s} gets {@code args[0]}, etc. If there are more arguments than placeholders, the unmatched arguments will
* be appended to the end of the formatted message in square braces.
*
* @param template a non-null string containing 0 or more {@code %s} placeholders.
* @param args the arguments to be substituted into the message template. Arguments are converted to strings
* using
* {@link String#valueOf(Object)}. Arguments can be null.
*/
// Note that this is somewhat-improperly used from Verify.java as well.
static String format(String template, Object... args) {
template = String.valueOf(template); // null -> "null"
// start substituting the arguments into the '%s' placeholders
StringBuilder builder = new StringBuilder(template.length() + 16 * args.length);
int templateStart = 0;
int i = 0;
while (i < args.length) {
int placeholderStart = template.indexOf("%s", templateStart);
if (placeholderStart == -1) {
break;
}
builder.append(template.substring(templateStart, placeholderStart));
builder.append(args[i++]);
templateStart = placeholderStart + 2;
}
builder.append(template.substring(templateStart));
// if we run out of placeholders, append the extra args in square braces
if (i < args.length) {
builder.append(" [");
builder.append(args[i++]);
while (i < args.length) {
builder.append(", ");
builder.append(args[i++]);
}
builder.append(']');
}
return builder.toString();
}
}