Checks.java
/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.test.internal.util;
import android.os.Looper;
/**
* Utility methods for checking null references, method arguments, and thread state to simplify
* other library code.
*/
public final class Checks {
private Checks() {}
public static <T> T checkNotNull(T reference) {
if (reference == null) {
throw new NullPointerException();
}
return reference;
}
public static <T> T checkNotNull(T reference, Object errorMessage) {
if (reference == null) {
throw new NullPointerException(String.valueOf(errorMessage));
}
return reference;
}
public static <T> 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;
}
/** Throw an {@link IllegalArgumentException} when {@code expression} is false. */
public static void checkArgument(boolean expression) {
if (!expression) {
throw new IllegalArgumentException();
}
}
/**
* Throw an {@link IllegalArgumentException} when {@code expression} is false with the specified
* {@code errorMessage}.
*/
public static void checkArgument(boolean expression, Object errorMessage) {
if (!expression) {
throw new IllegalArgumentException(String.valueOf(errorMessage));
}
}
/**
* Throw an {@link IllegalArgumentException} when {@code expression} is false with the message
* formatted by {@code errorMessageTemplate} and {@code errorMessageArgs}.
*/
public static void checkArgument(
boolean expression, String errorMessageTemplate, Object... errorMessageArgs) {
if (!expression) {
throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
}
}
public static void checkState(boolean expression) {
if (!expression) {
throw new IllegalStateException();
}
}
/**
* Throw an {@link IllegalStateException} when {@code expression} is false with the specified
* {@code errorMessage}.
*/
public static void checkState(boolean expression, Object errorMessage) {
if (!expression) {
throw new IllegalStateException(String.valueOf(errorMessage));
}
}
/**
* Throw an {@link IllegalStateException} when {@code expression} is false with the specified
* {@code errorMessage}.
*/
public static void checkState(
boolean expression, String errorMessageTemplate, Object... errorMessageArgs) {
if (!expression) {
throw new IllegalStateException(format(errorMessageTemplate, errorMessageArgs));
}
}
/**
* Checks if the current thread is the main thread, otherwise throws.
*
* @throws IllegalStateException if current thread is not the main thread.
*/
public static void checkMainThread() {
checkState(
Thread.currentThread().equals(Looper.getMainLooper().getThread()),
"Method cannot be called off the main application thread (on: %s)",
Thread.currentThread().getName());
}
/**
* Checks if the current thread is not the main thread, otherwise throws.
*
* @throws IllegalStateException if current thread is the main thread.
*/
public static void checkNotMainThread() {
checkState(
!Thread.currentThread().equals(Looper.getMainLooper().getThread()),
"Method cannot be called on the main application thread (on: %s)",
Thread.currentThread().getName());
}
private 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();
}
}