validating - Guava Assertions

最新推荐文章于 2023-10-12 21:15:00 发布

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本文介绍Guava库中提供的断言工具类Verify，该工具类提供了一组始终可用的断言方法，无需开启Java原生断言。通过示例演示了如何使用Verify进行数值校验、空值检查等操作，并展示了不同情况下的错误信息。

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Because turning on native Java assertions is a bother, the Guava team added a Verify class with replacement assertions always enabled.

The team recommends importing the Verify methods staticlly:

// validating/GuavaAssertions.java
// (c)2017 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 static com.google.common.base.Verify.*;

import com.google.common.base.*;

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
*/

run GuavaAssertions