Android Studio中的错误：无法找到符号变量fragment_main

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我发展我的第二款Android机应用，一个简单的计算器有以下操作Android Studio中的错误：无法找到符号变量fragment_main

加，减，乘，除，取模

代码：

XML：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" 
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"> 

<TableLayout 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:layout_gravity="center"> 

    <TableRow 
     android:layout_width="fill_parent" 
     android:layout_height="fill_parent"> 

     <TextView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:textAppearance="?android:textAppearanceMedium" 
      android:text="Number 1" 
      android:id="@+id/textView" 
      android:layout_column="1"/> 
     <EditText 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:inputType="number" 
      android:ems="10" 
      android:id="@+id/num1" 
      android:layout_column="3" 
      /> 


    </TableRow> 

    <TableRow 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"> 

     <TextView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:textAppearance="?android:attr/textAppearanceMedium" 
      android:text="Number 2" 
      android:id="@+id/textView2" 
      android:layout_column="1" /> 

     <EditText 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:inputType="number" 
      android:ems="10" 
      android:id="@+id/num2" 
      android:layout_column="3" /> 
    </TableRow> 

    <TableRow 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"> 

     <Button 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="+ADD" 
      android:id="@+id/btAdd" 
      android:layout_column="3" /> 
    </TableRow> 

    <TableRow 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"> 

     <Button 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="-Subtract" 
      android:id="@+id/btSub" 
      android:layout_column="3" /> 
    </TableRow> 

    <TableRow 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"> 

     <Button 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="xMultiply" 
      android:id="@+id/btMul" 
      android:layout_column="3" /> 
    </TableRow> 

    <TableRow 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"> 

     <Button 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="/ Divide" 
      android:id="@+id/btDiv" 
      android:layout_column="3" /> 
    </TableRow> 

    <TableRow 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"> 

     <Button 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="% Mod" 
      android:id="@+id/btMod" 
      android:layout_column="3" /> 
    </TableRow> 

    <TableRow 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"></TableRow> 

    <TableRow 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"> 

     <TextView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:textAppearance="?android:attr/textAppearanceMedium" 
      android:text="Result:" 
      android:id="@+id/result" 
      android:layout_column="1" /> 
    </TableRow> 
</TableLayout> 
</RelativeLayout>

Java代码是：

mainActivity.java

package in.infoexpo.sreerajm.secapp; 

    import android.app.Fragment; 
    import android.support.v7.app.AppCompatActivity; 
    import android.os.Bundle; 
    import android.text.Layout; 
    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; 

    public class MainActivity extends AppCompatActivity { 

    public static class PlaceholderFragment extends Fragment { 
     public PlaceholderFragment(){ 

     } 
     @Override 

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


      Button btAdd = (Button) rootView.findViewById(R.id.btAdd); 
      Button btSub = (Button) rootView.findViewById(R.id.btSub); 
      Button btMul = (Button) rootView.findViewById(R.id.btMul); 
      Button btDiv = (Button) rootView.findViewById(R.id.btDiv); 
      Button btMod = (Button) rootView.findViewById(R.id.btMod); 

      btAdd.setOnClickListener(new View.OnClickListener() { 
       public void onClick(View view) { 

        int n1, n2; 
        EditText num1 = (EditText) rootView.findViewById(R.id.num1); 
        EditText num2 = (EditText) rootView.findViewById(R.id.num2); 
        n1 = Integer.parseInt(num1.getText().toString()); 
        n2 = Integer.parseInt(num2.getText().toString()); 

        TextView result = (TextView) rootView.findViewById(R.id.result); 
        result.setText(n1 + n2); 
       } 

      }); 
      btSub.setOnClickListener(new View.OnClickListener() { 
       public void onClick(View view) { 

        int n1, n2; 
        EditText num1 = (EditText) rootView.findViewById(R.id.num1); 
        EditText num2 = (EditText) rootView.findViewById(R.id.num2); 
        n1 = Integer.parseInt(num1.getText().toString()); 
        n2 = Integer.parseInt(num2.getText().toString()); 

        TextView result = (TextView) rootView.findViewById(R.id.result); 
        result.setText(n1 - n2); 
       } 

      }); 
      btMul.setOnClickListener(new View.OnClickListener() { 
       public void onClick(View view) { 

        int n1, n2; 
        EditText num1 = (EditText) rootView.findViewById(R.id.num1); 
        EditText num2 = (EditText) rootView.findViewById(R.id.num2); 
        n1 = Integer.parseInt(num1.getText().toString()); 
        n2 = Integer.parseInt(num2.getText().toString()); 

        TextView result = (TextView) rootView.findViewById(R.id.result); 
        result.setText(n1 * n2); 
       } 

      }); 
      btDiv.setOnClickListener(new View.OnClickListener() { 
       public void onClick(View view) { 

        int n1, n2; 
        EditText num1 = (EditText) rootView.findViewById(R.id.num1); 
        EditText num2 = (EditText) rootView.findViewById(R.id.num2); 
        n1 = Integer.parseInt(num1.getText().toStenter code herering()); 
        n2 = Integer.parseInt(num2.getText().toString()); 

        TextView result = (TextView) rootView.findViewById(R.id.result); 
        result.setText(n1/n2); 
       } 

      }); 
      btMod.setOnClickListener(new View.OnClickListener() { 
       public void onClick(View view) { 

        int n1, n2; 
        EditText num1 = (EditText) rootView.findViewById(R.id.num1); 
        EditText num2 = (EditText) rootView.findViewById(R.id.num2); 
        n1 = Integer.parseInt(num1.getText().toString()); 
        n2 = Integer.parseInt(num2.getText().toString()); 

        TextView result = (TextView) rootView.findViewById(R.id.result); 
        result.setText(n1 % n2); 
       } 

      }); 

      return rootView; 


     } 
    } 
}

我尝试了许多变化，但不能删除一个错误
错误：无法找到符号变量fragment_main PLZ帮我修正这个错误。

来源

2015-08-29 djsreeraj

你把xml可能吗？它被命名为fragment_main.xml和文件夹下把RES /布局

来源

2015-08-29 13:18:15

我的XML文件的名称是activity_main.xml中的文件夹下的RES /布局 – djsreeraj

'最后查看rootView = inflater.inflate（R。 ' 您的代码在此查找fragment_main.xml，您应该将代码更改为 'final查看rootView = inflater.inflate（R.layout.activity_main，container，false）;' –

或者你必须创建一个新的xml fragment_main.xml –

Android Studio中的错误：无法找到符号变量fragment_main

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