Question

我正在开发我的第二个Android应用程序，一个简单的计算器通过以下操作

加法，减法，乘法，除法，模数

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;


        }
    }
}

我尝试了很多更改，但无法删除一个错误错误：找不到符号变量fragment_main Plz帮我修复错误。

Answer 1

你有可能把xml？它必须命名为 fragment_main.xml 并放在文件夹 res / layout

下

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

1 个答案: