OnJava8-Examples/validating/GuavaPreconditions.java at master · CSapprenticeWT/OnJava8-Examples · GitHub

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// validating/GuavaPreconditions.java

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// Demonstrating Guava Preconditions

import java.util.function.*;

import static com.google.common.base.Preconditions.*;

public class GuavaPreconditions {

static void test(Consumer<String> c, String s) {

try {

System.out.println(s);

c.accept(s);

System.out.println("Success");

} catch(Exception e) {

String type = e.getClass().getSimpleName();

String msg = e.getMessage();

System.out.println(type +

(msg == null ? "" : ": " + msg));

}

public static void main(String[] args) {

test(s -> s = checkNotNull(s), "X");

test(s -> s = checkNotNull(s), null);

test(s -> s = checkNotNull(s, "s was null"), null);

test(s -> s = checkNotNull(

s, "s was null, %s %s", "arg2", "arg3"), null);

test(s -> checkArgument(s == "Fozzie"), "Fozzie");

test(s -> checkArgument(s == "Fozzie"), "X");

test(s -> checkArgument(s == "Fozzie"), null);

test(s -> checkArgument(

s == "Fozzie", "Bear Left!"), null);

test(s -> checkArgument(

s == "Fozzie", "Bear Left! %s Right!", "Frog"),

null);

test(s -> checkState(s.length() > 6), "Mortimer");

test(s -> checkState(s.length() > 6), "Mort");

test(s -> checkState(s.length() > 6), null);

test(s ->

checkElementIndex(6, s.length()), "Robert");

test(s ->

checkElementIndex(6, s.length()), "Bob");

test(s ->

checkElementIndex(6, s.length()), null);

test(s ->

checkPositionIndex(6, s.length()), "Robert");

test(s ->

checkPositionIndex(6, s.length()), "Bob");

test(s ->

checkPositionIndex(6, s.length()), null);