OnJava8-Examples/validating/GuavaAssertions.java

// validating/GuavaAssertions.java
// (c)2021 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Assertions that are always enabled.
import com.google.common.base.*;
import static com.google.common.base.Verify.*;

public class GuavaAssertions {
  public static void main(String[] args) {
    verify(2 + 2 == 4);
    try {
      verify(1 + 2 == 4);
    } catch(VerifyException e) {
      System.out.println(e);
    }
    try {
      verify(1 + 2 == 4, "Bad math");
    } catch(VerifyException e) {
      System.out.println(e.getMessage());
    }
    try {
      verify(1 + 2 == 4, "Bad math: %s", "not 4");
    } catch(VerifyException e) {
      System.out.println(e.getMessage());
    }
    String s = "";
    s = verifyNotNull(s);
    s = null;
    try {
      verifyNotNull(s);
    } catch(VerifyException e) {
      System.out.println(e.getMessage());
    }
    try {
      verifyNotNull(
        s, "Shouldn't be null: %s", "arg s");
    } catch(VerifyException e) {
      System.out.println(e.getMessage());
    }
  }
}
/* Output:
com.google.common.base.VerifyException
Bad math
Bad math: not 4
expected a non-null reference
Shouldn't be null: arg s
*/