source not found错误：运行时异常

Question

我是Android应用程序开发的新手，我一直试图解决这个问题很长一段时间但找不到解决方案。我创建了一个简单的应用程序，它接受5个变量中的数据，然后计算这些变量的总和。编译代码时没有错误，但在模拟器上运行应用程序时会出错：

  

找不到来源错误

Log Cat Stack Trace

<disconnected>DalvikVM[localhost:8633]  
DalvikVM[localhost:8610]    
    Thread [<1> main] (Suspended (exception RuntimeException))  
        <VM does not provide monitor information>   
        ActivityThread.performLaunchActivity(ActivityThread$ActivityClientRecord, Intent) line: 2180    
        ActivityThread.handleLaunchActivity(ActivityThread$ActivityClientRecord, Intent) line: 2230 
        ActivityThread.access$600(ActivityThread, ActivityThread$ActivityClientRecord, Intent) line: 141    
        ActivityThread$H.handleMessage(Message) line: 1234  
        ActivityThread$H(Handler).dispatchMessage(Message) line: 99 
        Looper.loop() line: 137 
        ActivityThread.main(String[]) line: 5041    
        Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]  
        Method.invoke(Object, Object...) line: 511  
        ZygoteInit$MethodAndArgsCaller.run() line: 793  
        ZygoteInit.main(String[]) line: 560 
        NativeStart.main(String[]) line: not available [native method]  
    Thread [<10> Binder_2] (Running)    
    Thread [<9> Binder_1] (Running) 

MainActivity.java

package com.example.totalmarks;


import android.app.Activity;

import android.os.Bundle;

import android.widget.EditText;

import android.widget.TextView;

import android.widget.Button;

import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;


public class MainActivity extends Activity
{
      //TextWatcher
    private TextWatcher textWatcher = new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i2, int i3)
       {

        }

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) {
            checkFieldsForEmptyValues();
        }

        @Override
        public void afterTextChanged(Editable editable) {
        }
    };

  EditText regno;
  EditText cat1;
  EditText cat2;
  EditText quiz1;
  EditText quiz2;
  EditText quiz3;
  TextView tt;
  Button calculate;
  float a=0;
  float b=0;
  float c=0;
  float d=0;
  float e=0;
  float f=0;
  String reg;
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState)
  {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      regno=(EditText)findViewById(R.id.regno);
      cat1=(EditText)findViewById(R.id.cat1);
      cat2=(EditText)findViewById(R.id.cat2);
      quiz1=(EditText)findViewById(R.id.quiz1);
      quiz2=(EditText)findViewById(R.id.quiz2);
      quiz3=(EditText)findViewById(R.id.quiz3);
      tt=(TextView)findViewById(R.id.tt);
      //set listeners
      cat1.addTextChangedListener(textWatcher);
      cat2.addTextChangedListener(textWatcher);
      quiz1.addTextChangedListener(textWatcher);
      quiz2.addTextChangedListener(textWatcher);
      quiz3.addTextChangedListener(textWatcher);
      regno.addTextChangedListener(textWatcher);
      // run once to disable if empty
      checkFieldsForEmptyValues();
      calculate=(Button) findViewById(R.id.calculate);
      calculate.setOnClickListener(new Button.OnClickListener()
       {
         public void onClick(View  v) 
      {
     calculate();}});
  }
   private void calculate()
  {
      a=Float.parseFloat(cat1.getText().toString());
      b=Float.parseFloat(cat2.getText().toString());
      c=Float.parseFloat(quiz1.getText().toString());
      d=Float.parseFloat(quiz2.getText().toString());
      e=Float.parseFloat(quiz3.getText().toString());
      f=a+b+c+d+e;
      tt.setText(Float.toString(f));
  }
   private  void checkFieldsForEmptyValues(){
       Button b = (Button) findViewById(R.id.calculate);
       String s1 = cat1.getText().toString();
       String s2 = cat2.getText().toString();
       String s3 = quiz1.getText().toString();
       String s4 = quiz2.getText().toString();
       String s5 = quiz3.getText().toString();
       String s6 = regno.getText().toString();
       String s7=s6.substring(0,2);
       int digits=Integer.parseInt(s7);
       if(s1.equals("") || s2.equals("") || s3.equals("") || s4.equals("") || s5.equals("") || s6.equals("") )
       b.setEnabled(false);
       else if(digits<10 || digits>14)
       {
       regno.setError("Enter Correct Registration number");
       b.setEnabled(false);
       }
       else
        b.setEnabled(true);
        }
}

清单文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.totalmarks"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="9"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>