java - java中断言后出现NullPointerException

Question

以下方法是名为election_date 的字段的 setter ，该字段的类型为java.util.date。它是 tomcat 应用程序的一部分。

执行后，我收到一个空指针异常:

    System.out.println("ELECTION DATE: " + this.election_date.toString());

<小时/>

public void setElection_date(Date election_date) {

    this.election_date = election_date;
    assert (this.election_date != null);
    assert (this.election_date.toString()) != null;
    System.out.println("ELECTION DATE: " + this.election_date.toString());
}

<小时/>

编辑:请不要告诉我它正在被垃圾收集。我可能稍微偏离巴尔默峰，但也不是那么远。

Answer 1

默认情况下禁用断言。你的变量election_date是 null .

添加-ea至JAVA_OPTS在运行 Tomcat 之前。

Programming With Assertions: Enabling and Disabling Assertions

By default, assertions are disabled at runtime. Two command-line switches allow you to selectively enable or disable assertions.

To enable assertions at various granularities, use the -enableassertions, or -ea, switch. To disable assertions at various granularities, use the -disableassertions, or -da, switch.

另请参阅问题:How can I enable java assertions in Tomcat