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问答 查询不到数据提示NullPointerException?
发布于 168天前 作者 ftqiao 220 次浏览 复制 上一个帖子 下一个帖子
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根据Dao手册写例子,
name是主键。fetch的时候,name = ‘NoExist’是不存在的,这时候提示的错误信息是NullPointerException?
个人觉得这错误提示的好像不大合理~

[DEBUG] 19:08:39.886 org.nutz.dao.impl.sql.run.NutDaoExecutor.printSQL(NutDaoExecutor.java:388) - SELECT * FROM t_person  WHERE name=?
    |   1 |
    |-----|
    | Noe |
  For example:> "SELECT * FROM t_person  WHERE name='Noe'"

java.lang.NullPointerException
	at DaoTest.testUpdateIg(DaoTest.java:28)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

下为代码

public class DaoTest {
    public static SimpleDataSource dataSource = new SimpleDataSource();
    public static Dao dao;

    @Before
    public void setUp() throws Exception {
        dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1/nutzdemo");
        dataSource.setUsername("root");
        dataSource.setPassword("888888");
        dao = new NutDao(dataSource);
//        dao.create(Person.class, false);//drop if exists false
    }
    @Test
    public void testUpdateIg() {
        Person person = dao.fetch(Person.class, "NoExist");
        System.out.println("before:" + person.toString());
//        person.setAge(46);
//        person.setName("HAHA");
//        Daos.ext(dao, FieldFilter.create(Person.class, "^name$")).update(person);
//        Person afterP = dao.fetch(Person.class, "A");
//        System.out.println("afterP:" + person.toString());
    }
}
2 回复

dao.fetch取一个不存在的数据,所以返回null,再使用,不就npe了?

噗~~~~~ 一口老血喷一显示器! 脑袋短路了

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