不幸的是，（我的应用程序）已停止。 Eclipse Android

Question

我是一名Android开发人员，我正在尝试构建一个简单的应用程序，但在模拟器中出现此错误（不幸的是，（应用程序）已意外停止）。

logcat的

http://i.stack.imgur.com/VZhuL.png

package com.eebax.mjcalculator; 

import android.support.v7.app.ActionBarActivity; 
import android.support.v7.app.ActionBar; 
import android.support.v4.app.Fragment; 
import android.os.Bundle; 
import android.view.LayoutInflater; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.TextView; 
import android.os.Build; 

public class MainActivity extends ActionBarActivity { 
EditText one, two; 
Button plus, minus, multiply, divide; 
TextView showres; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    one = (EditText)findViewById(R.id.editText1); 
    two = (EditText)findViewById(R.id.editText2); 
    plus = (Button)findViewById(R.id.button1); 
    minus = (Button)findViewById(R.id.button2); 
    multiply = (Button)findViewById(R.id.button3); 
    divide = (Button)findViewById(R.id.button4); 
    showres = (TextView)findViewById(R.id.textView3); 

    plus.setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View arg0) { 
      // TODO Auto-generated method stub 
      try { 
       int n1 = Integer.parseInt(one.getText().toString()); 
       int n2 = Integer.parseInt(two.getText().toString()); 
       int sum = n1+n2; 
       showres.setText(" "+sum); 
      } 
      catch(Exception e){ 
      } 


     } 
    }); 

    if (savedInstanceState == null) { 
     getSupportFragmentManager().beginTransaction() 
       .add(R.id.container, new PlaceholderFragment()) 
       .commit(); 
    } 
} 


@Override 
public boolean onCreateOptionsMenu(Menu menu) { 

    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.main, menu); 
    return true; 
} 

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    // Handle action bar item clicks here. The action bar will 
    // automatically handle clicks on the Home/Up button, so long 
    // as you specify a parent activity in AndroidManifest.xml. 
    int id = item.getItemId(); 
    if (id == R.id.action_settings) { 
     return true; 
    } 
    return super.onOptionsItemSelected(item); 
} 

/** 
* A placeholder fragment containing a simple view. 
*/ 
public static class PlaceholderFragment extends Fragment { 

    public PlaceholderFragment() { 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_main, container, false); 
     return rootView; 
    } 
} 

} 

清单

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

<uses-sdk 
    android:minSdkVersion="10" 
    android:targetSdkVersion="19" /> 

<application 
    android:allowBackup="true" 
    android:icon="@drawable/ic_launcher" 
    android:label="@string/app_name" 
    android:theme="@style/AppTheme" > 
    <activity 
     android:name="com.eebax.mjcalculator.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> 

Answer 1

在你MainActivity.java在行中没有34，你正试图初始化一些小部件，不存在在你的XML布局，您已将其设置在您的setContentView（R.layout ....

这就是为什么你正在创造nullpointerexception。

编辑：更改setContentView(R.layout.activity_main)到setContentView(R.layout.fragment_main)