android应用程序在启动时崩溃，Logcat:Didn'；“找不到类”；[软件包名称]”；at/data/app/[软件包名称]

希望你能帮我解决我的问题。我的应用程序在启动时崩溃，所以我尝试使用LogCat查找错误。如标题中所述，错误消息说：

07-29 03:49:46.734: E/AndroidRuntime(837): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.calculate.firsttry/com.example.calculate.firsttry.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.example.calculate.firsttry.MainActivity" on path: /data/app/com.example.calculate.firsttry-1.apk
07-29 03:49:46.734: E/AndroidRuntime(837): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.calculate.firsttry.MainActivity" on path: /data/app/com.example.calculate.firsttry-1.apk

看来我在什么地方漏掉了申报单。问题是，我不知道在哪里。这不是我的第一个应用，我想我已经重复了我以前做的每一步

这是我的应用程序的代码：

package com.example.calculate.firsttry;

 import org.ksoap2.SoapEnvelope;
 import org.ksoap2.serialization.SoapObject;
 import org.ksoap2.serialization.SoapSerializationEnvelope;
 import org.ksoap2.transport.HttpTransportSE;import android.app.Activity;
 import android.os.Bundle;
 import android.widget.TextView;

 public class AndroidWSDLFrontEnd extends Activity {

 private String METHOD_NAME = "add"; // our webservice method name
 private String NAMESPACE = "http://calculator.backend.org";;
 private String SOAP_ACTION = NAMESPACE + METHOD_NAME; // NAMESPACE + method name
 private static final String URL = "http://10.35.108.154:8080/AndroidBackend/services/Calculator?wsdl";;// you must use ipaddress here, don’t use Hostname or localhost

/** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

TextView tv = (TextView) findViewById(R.id.txtAddition);
 try
 {
 SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME);
 request.addProperty("a", 5);
 request.addProperty("b", 15);
 SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
 envelope.dotNet = true;
 envelope.setOutputSoapObject(request);
 HttpTransportSE androidHttpTransport = new HttpTransportSE(URL);
 androidHttpTransport.call(SOAP_ACTION,envelope);
 Object result = envelope.getResponse();
 System.out.println("Result: " + result.toString());
 ((TextView) findViewById (R.id.txtAddition)).setText("Addition :" +result.toString());
 } catch (Exception E) {
 E.printStackTrace();
 ((TextView) findViewById (R.id.txtAddition)).setText("ERROR: "    + E.getClass().getName() + "," + E.getMessage());
 }
 }
 }

也许我错过了什么。我不能再具体说明这个问题了。我得到的只是代码和错误信息。那么如何让我的应用程序运行呢

谢谢你的帮助。

一些建议

1） 如果尚未声明，请在

AndroidManifest.xml

文件中声明活动

2） 似乎您正试图打开

main活动

类/活动

，并在问题中添加了

AndroidWSDLFrontEnd

活动，希望您调用的是正确的活动，请在Manifest/activitydeclarrion和启动活动时检查相应类的名称

07-29 03:49:46.734: E/AndroidRuntime(837): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.calculate.firsttry.**MainActivity**" // here it says MainActivity not found, Check the name of your activity

---

在您的

AndroidManifest.xml

换衣服试试

 <activity
        android:name="com.example.calculate.firsttry.MainActivity"
        ............

    </activity>

---

我在Android Studio 0.2.10中遇到了这个问题，不得不在Android Studio中执行Gradle
清理。
谢谢，这解决了最初的问题，我忘了更改清单中类的名称。现在它仍然不起作用，在我的代码第26行有一个错误，但由于我试图解决张贴的错误消息，再次感谢您帮助我。
 <activity
            android:name="com.example.calculate.firsttry.AndroidWSDLFrontEnd"
            ............

        </activity>