java - 如何修复包 R 不存在 setContentView(R.layout.activity_main) 及其后果？

Question

最初的错误消息是:

error: package R does not exist setContentView(R.layout.activity_main);

然后我在 StackOverflow 中读到了很多关于这个问题的答案，所以我尝试检查 MainActivity 中的包名称以及 list 文件，然后导入 mypackage.R，然后问题消息变成这样:

    Creating myapp-debug-unaligned.apk and signing it with a debug key...
C:\Users\m0unta\AppData\Local\Android\android-sdk\tools\ant\build.xml:960: The following error occurred while executing this line:
C:\Users\m0unta\AppData\Local\Android\android-sdk\tools\ant\build.xml:971: The following error occurred while executing this line:
C:\Users\m0unta\AppData\Local\Android\android-sdk\tools\ant\build.xml:314: 
java.lang.NoClassDefFoundError: Could not initialize class sun.security.x509.X500Name
    at com.android.sdklib.internal.build.SignedJarBuilder.writeSignatureBlock(SignedJarBuilder.java:384)
    at com.android.sdklib.internal.build.SignedJarBuilder.close(SignedJarBuilder.java:273)
    at com.android.sdklib.build.ApkBuilder.sealApk(ApkBuilder.java:795)
    at com.android.ant.ApkBuilderTask.execute(ApkBuilderTask.java:371)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:293)
    at sun.reflect.GeneratedMethodAccessor269.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:293)
    at sun.reflect.GeneratedMethodAccessor269.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:396)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:293)
    at sun.reflect.GeneratedMethodAccessor269.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68)
    at com.android.ant.IfElseTask.execute(IfElseTask.java:124)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:293)
    at sun.reflect.GeneratedMethodAccessor269.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68)
    at com.android.ant.IfElseTask.execute(IfElseTask.java:124)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:293)
    at sun.reflect.GeneratedMethodAccessor269.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:293)
    at sun.reflect.GeneratedMethodAccessor269.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:396)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:293)
    at sun.reflect.GeneratedMethodAccessor269.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.Target.execute(Target.java:435)
    at org.apache.tools.ant.Target.performTasks(Target.java:456)
    at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1405)
    at org.apache.tools.ant.Project.executeTarget(Project.java:1376)
    at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    at org.apache.tools.ant.Project.executeTargets(Project.java:1260)
    at org.apache.tools.ant.module.bridge.impl.BridgeImpl.run(BridgeImpl.java:286)
    at org.apache.tools.ant.module.run.TargetExecutor.run(TargetExecutor.java:555)
    at org.netbeans.core.execution.RunClassThread.run(RunClassThread.java:153)
BUILD FAILED (total time: 2 seconds)

注意:我使用的是 Netbeans，而不是 Android Studio(也许这就是问题所在，我不知道)

Answer 1

R.java 是在构建应用程序时生成的。尝试解决此错误要做的第一件事是清理并重建您的项目。如果仍然出现相同的错误，请检查所有 XML 文件。 AndroidManifest.xml 和任何布局或其他 XML 资源文件中的错误将停止生成 R.java。

我强烈建议您切换到 Android Studio，因为它是官方支持的 IDE。