Java 为什么来自AlertDialog的输入不显示在RecyclerView中？

我想从AlertDialog对话框中获取输入，并将其设置为2个变量，然后使用这些变量作为参数，使用recyclerview创建列表

当代码处于该状态时，它会弹出对话框，当我输入信息并按“添加”时，屏幕上不会显示任何内容

这是我的Java文件：

public class tab1Expenses extends Fragment {
List<ExRow> expenseList = new ArrayList<>();
RecyclerView recyclerView;
ExpensesAdapter mAdapter;
Button btnEx;
EditText txtExName;
EditText txtExAmount;

public void expenseData() {

    ExRow exs = new ExRow(txtExNa, txtExAm);
    expenseList.add(exs);

    mAdapter.notifyDataSetChanged();

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    final View rootView = inflater.inflate(R.layout.tab1expense, container, false);
    btnEx = (Button) rootView.findViewById(R.id.btnEx);
    recyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);

    mAdapter = new ExpensesAdapter(expenseList);
    RecyclerView.LayoutManager mLayoutManager = new RecyclerView.LayoutManager() {
        @Override
        public RecyclerView.LayoutParams generateDefaultLayoutParams() {

            return null;
        }

    };
    recyclerView.setLayoutManager(mLayoutManager);
    recyclerView.setItemAnimator(new DefaultItemAnimator());
    recyclerView.setAdapter(mAdapter);

    btnEx.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            View view = LayoutInflater.from(tab1Expenses.this.getActivity())
                    .inflate(R.layout.add_ex, null);
            txtExName = (EditText) view.findViewById(R.id.exName);
            txtExAmount = (EditText) view.findViewById(R.id.exAmount);
            AlertDialog.Builder add = new AlertDialog.Builder(tab1Expenses.this.getActivity());
                    add.setCancelable(true)
                    .setTitle("Enter Expense:")
                    .setView(view)
                    .setPositiveButton("Add",
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    expenseData();
                                }
                            });
            Dialog dialog = add.create();
            dialog.show();
        }
    });

    return rootView;
   }
}

public类tab1Expenses扩展片段{
List expenseList=new ArrayList（）；
回收视图回收视图；
费用支出支出支出；
按钮btnEx；
编辑文本txtExName；
EditText txtExAmount；
公共支出数据（）{
ExRow exs=新ExRow（txtExNa，txtExAm）；
expenseList.add（exs）；
mAdapter.notifyDataSetChanged（）；
}
@凌驾
创建视图上的公共视图（布局、充气机、视图组容器、，
Bundle savedInstanceState）{
最终视图根视图=充气机。充气（R.layout.tab1expense，容器，错误）；
btnEx=（按钮）rootView.findviewbyd（R.id.btnEx）；
recyclerView=（recyclerView）rootView.findviewbyd（R.id.recycler\u视图）；
mAdapter=新支出调整器（支出列表）；
RecyclerView.LayoutManager mLayoutManager=新建RecyclerView.LayoutManager（）{
@凌驾
public RecyclerView.LayoutParams GeneratedDefaultLayoutParams（）{
返回null；
}
};
recyclerView.setLayoutManager（mLayoutManager）；
setItemAnimator（新的DefaultItemAnimator（））；
recyclerView.setAdapter（mAdapter）；
btnEx.setOnClickListener（新视图.OnClickListener（）{
@凌驾
公共void onClick（视图v）{
View=LayoutInflater.from（tab1Expenses.this.getActivity（））
.充气（R.layout.add_ex，空）；
txtExName=（EditText）view.findViewById（R.id.exName）；
txtExAmount=（EditText）view.findviewbyd（R.id.exAmount）；
AlertDialog.Builder add=新建AlertDialog.Builder（tab1Expenses.this.getActivity（））；
add.setCancelable（true）
.setTitle（“输入费用：”）
.setView（视图）
.setPositiveButton（“添加”，
新建DialogInterface.OnClickListener（）{
@凌驾
public void onClick（DialogInterface dialog，int which）{
expenseData（）；
}
});
Dialog=add.create（）；
dialog.show（）；
}
});
返回rootView；
}
}

---

以下是相关的XML文件：

<Button
    android:text="Add Expense"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/btnEx"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:width="800dp"
    android:textAppearance="@style/TextAppearance.AppCompat.Widget.Switch"
    android:background="@android:color/black"
    android:textColor="@android:color/holo_green_light"
    android:textColorLink="@android:color/holo_green_light" />

<ScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_alignParentBottom="true"
    android:layout_alignParentStart="true"
    android:layout_marginBottom="17dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycler_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scrollbars="vertical" />

    </LinearLayout>

</ScrollView>

---

以及用于添加输入的XML文件：

 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/background_light">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:ems="10"
        android:id="@+id/exName"
        android:textColorLink="@android:color/holo_green_light"
        android:textColorHighlight="@android:color/holo_green_light"
        android:editable="false"
        android:hint="Expense Name" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="numberDecimal"
        android:ems="10"
        android:id="@+id/exAmount"
        android:textColorLink="@android:color/holo_green_light"
        android:textColorHighlight="@android:color/holo_green_light"
        android:hint="Expense Amount" />

</LinearLayout>

---

好的，我可以看到问题是因为它无法找到名为

txtExName

的

EditText

和

txtExAmount

。所以

切断这两条线：

recyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);
txtExName = (EditText) rootView.findViewById(R.id.exName); //<---This one
txtExAmount = (EditText) rootView.findViewById(R.id.exAmount); // <--And this one

---

希望对您有所帮助。

您的XML文件中的编辑文本发布在哪里

可能它返回null，因为它找不到任何EditText：

String txtExNa = (txtExAmount.getText()).toString(); //here is crash, i think

---

对不起我的英语，我希望这有帮助

您需要从

视图

而非

根视图

获取

txtExName

和

txtExAmount

的参考。因此，从最新代码中删除这些行

txtExName = (EditText) rootView.findViewById(R.id.exName); 
txtExAmount = (EditText) rootView.findViewById(R.id.exAmount); 

把这些线加在同一点上

txtExName = (EditText) view.findViewById(R.id.exName); 
txtExAmount = (EditText) view.findViewById(R.id.exAmount); 

---

好的，这可能是最后的答案。我会尽力掩盖你想做的一切

//这是

tab1expense.xml

（不带工具栏）

//现在有一个名为

ExRow.java

public class ExRow{

    String str_txtExNa,str_txtExAm;

    ExRow(String str_txtExNa, String str_txtExAm){
        this.str_txtExNa=str_txtExNa;
        this.str_txtExAm=str_txtExAm;
    }

    public String getNa()
    {
       return str_txtExNa;
    }

    public String getAm()
    {
      return str_txtExAm;
    }
}

public class tab1Expenses extends Fragment {

    ArrayList<ExRow> expenseList = new ArrayList<>();
    RecyclerView recyclerView;
    ExpensesAdapter mAdapter;
    Button btnEx;
    EditText txtExName;
    EditText txtExAmount;

    public void expenseData(String txtExNa,String txtExAm) {
        ExRow exs = new ExRow(txtExNa, txtExAm);
        expenseList.add(exs);
        mAdapter.notifyDataSetChanged();
    }

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    final View rootView = inflater.inflate(R.layout.tab1expense, container, false);
    btnEx = (Button) rootView.findViewById(R.id.btnEx);
    recyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);

    mAdapter = new ExpensesAdapter(expenseList);
    recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
    recyclerView.setItemAnimator(new DefaultItemAnimator());
    recyclerView.setAdapter(mAdapter);

    btnEx.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            View view = LayoutInflater.from(tab1Expenses.this.getActivity())
                    .inflate(R.layout.add_ex, null);
            txtExName = (EditText) view.findViewById(R.id.exName);
            txtExAmount = (EditText) view.findViewById(R.id.exAmount);
            AlertDialog.Builder add = new AlertDialog.Builder(tab1Expenses.this.getActivity());
                    add.setCancelable(true)
                    .setTitle("Enter Expense:")
                    .setView(view)
                    .setPositiveButton("Add",
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    expenseData(txtExName.getText().toString(),txtExAmount`enter code here`.getText().toString() );
                                }
                            });
            Dialog dialog = add.create();
            dialog.show();
        }
    });

    return rootView;
   }
}

public class ExpensesAdapter extends RecyclerView.Adapter<ExpensesAdapter.ViewHolder> {

    private ArrayList<ExRow> expenseList;

    // Constructor of the class
    public ExpensesAdapter(ArrayList<ExRow> expenseList) {
        this.expenseList = expenseList;
    }

    // get the size of the list
    @Override
    public int getItemCount() {
        return expenseList == null ? 0 : expenseList.size();
    }


    // specify the row layout file
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_item_view, parent, false);
        ViewHolder myViewHolder = new ViewHolder(view);
        return myViewHolder;
    }

    // load data in each row element
    @Override
    public void onBindViewHolder(final ViewHolder holder, final int listPosition) {
        holder.row_name.setText(expenseList.get(listPosition).getNa());
        holder.row_amount.setText(expenseList.get(listPosition).getAm());
    }

    // Static inner class to initialize the views of rows
    static class ViewHolder extends RecyclerView.ViewHolder{
        public TextView row_name,row_amount;
        public ViewHolder(View itemView) {
            super(itemView);
            row_name = (TextView) itemView.findViewById(R.id.row_name);
            row_amount = (TextView) itemView.findViewById(R.id.row_amount);
        }
    }
}

//现在，您的

选项卡1 expenses.java

public class ExRow{

    String str_txtExNa,str_txtExAm;

    ExRow(String str_txtExNa, String str_txtExAm){
        this.str_txtExNa=str_txtExNa;
        this.str_txtExAm=str_txtExAm;
    }

    public String getNa()
    {
       return str_txtExNa;
    }

    public String getAm()
    {
      return str_txtExAm;
    }
}

public class tab1Expenses extends Fragment {

    ArrayList<ExRow> expenseList = new ArrayList<>();
    RecyclerView recyclerView;
    ExpensesAdapter mAdapter;
    Button btnEx;
    EditText txtExName;
    EditText txtExAmount;

    public void expenseData(String txtExNa,String txtExAm) {
        ExRow exs = new ExRow(txtExNa, txtExAm);
        expenseList.add(exs);
        mAdapter.notifyDataSetChanged();
    }

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    final View rootView = inflater.inflate(R.layout.tab1expense, container, false);
    btnEx = (Button) rootView.findViewById(R.id.btnEx);
    recyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);

    mAdapter = new ExpensesAdapter(expenseList);
    recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
    recyclerView.setItemAnimator(new DefaultItemAnimator());
    recyclerView.setAdapter(mAdapter);

    btnEx.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            View view = LayoutInflater.from(tab1Expenses.this.getActivity())
                    .inflate(R.layout.add_ex, null);
            txtExName = (EditText) view.findViewById(R.id.exName);
            txtExAmount = (EditText) view.findViewById(R.id.exAmount);
            AlertDialog.Builder add = new AlertDialog.Builder(tab1Expenses.this.getActivity());
                    add.setCancelable(true)
                    .setTitle("Enter Expense:")
                    .setView(view)
                    .setPositiveButton("Add",
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    expenseData(txtExName.getText().toString(),txtExAmount`enter code here`.getText().toString() );
                                }
                            });
            Dialog dialog = add.create();
            dialog.show();
        }
    });

    return rootView;
   }
}

public class ExpensesAdapter extends RecyclerView.Adapter<ExpensesAdapter.ViewHolder> {

    private ArrayList<ExRow> expenseList;

    // Constructor of the class
    public ExpensesAdapter(ArrayList<ExRow> expenseList) {
        this.expenseList = expenseList;
    }

    // get the size of the list
    @Override
    public int getItemCount() {
        return expenseList == null ? 0 : expenseList.size();
    }


    // specify the row layout file
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_item_view, parent, false);
        ViewHolder myViewHolder = new ViewHolder(view);
        return myViewHolder;
    }

    // load data in each row element
    @Override
    public void onBindViewHolder(final ViewHolder holder, final int listPosition) {
        holder.row_name.setText(expenseList.get(listPosition).getNa());
        holder.row_amount.setText(expenseList.get(listPosition).getAm());
    }

    // Static inner class to initialize the views of rows
    static class ViewHolder extends RecyclerView.ViewHolder{
        public TextView row_name,row_amount;
        public ViewHolder(View itemView) {
            super(itemView);
            row_name = (TextView) itemView.findViewById(R.id.row_name);
            row_amount = (TextView) itemView.findViewById(R.id.row_amount);
        }
    }
}

//最后是适配器类，即，

ExpensesAdapter.java

public class ExRow{

    String str_txtExNa,str_txtExAm;

    ExRow(String str_txtExNa, String str_txtExAm){
        this.str_txtExNa=str_txtExNa;
        this.str_txtExAm=str_txtExAm;
    }

    public String getNa()
    {
       return str_txtExNa;
    }

    public String getAm()
    {
      return str_txtExAm;
    }
}

public class tab1Expenses extends Fragment {

    ArrayList<ExRow> expenseList = new ArrayList<>();
    RecyclerView recyclerView;
    ExpensesAdapter mAdapter;
    Button btnEx;
    EditText txtExName;
    EditText txtExAmount;

    public void expenseData(String txtExNa,String txtExAm) {
        ExRow exs = new ExRow(txtExNa, txtExAm);
        expenseList.add(exs);
        mAdapter.notifyDataSetChanged();
    }

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    final View rootView = inflater.inflate(R.layout.tab1expense, container, false);
    btnEx = (Button) rootView.findViewById(R.id.btnEx);
    recyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);

    mAdapter = new ExpensesAdapter(expenseList);
    recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
    recyclerView.setItemAnimator(new DefaultItemAnimator());
    recyclerView.setAdapter(mAdapter);

    btnEx.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            View view = LayoutInflater.from(tab1Expenses.this.getActivity())
                    .inflate(R.layout.add_ex, null);
            txtExName = (EditText) view.findViewById(R.id.exName);
            txtExAmount = (EditText) view.findViewById(R.id.exAmount);
            AlertDialog.Builder add = new AlertDialog.Builder(tab1Expenses.this.getActivity());
                    add.setCancelable(true)
                    .setTitle("Enter Expense:")
                    .setView(view)
                    .setPositiveButton("Add",
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    expenseData(txtExName.getText().toString(),txtExAmount`enter code here`.getText().toString() );
                                }
                            });
            Dialog dialog = add.create();
            dialog.show();
        }
    });

    return rootView;
   }
}

public class ExpensesAdapter extends RecyclerView.Adapter<ExpensesAdapter.ViewHolder> {

    private ArrayList<ExRow> expenseList;

    // Constructor of the class
    public ExpensesAdapter(ArrayList<ExRow> expenseList) {
        this.expenseList = expenseList;
    }

    // get the size of the list
    @Override
    public int getItemCount() {
        return expenseList == null ? 0 : expenseList.size();
    }


    // specify the row layout file
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_item_view, parent, false);
        ViewHolder myViewHolder = new ViewHolder(view);
        return myViewHolder;
    }

    // load data in each row element
    @Override
    public void onBindViewHolder(final ViewHolder holder, final int listPosition) {
        holder.row_name.setText(expenseList.get(listPosition).getNa());
        holder.row_amount.setText(expenseList.get(listPosition).getAm());
    }

    // Static inner class to initialize the views of rows
    static class ViewHolder extends RecyclerView.ViewHolder{
        public TextView row_name,row_amount;
        public ViewHolder(View itemView) {
            super(itemView);
            row_name = (TextView) itemView.findViewById(R.id.row_name);
            row_amount = (TextView) itemView.findViewById(R.id.row_amount);
        }
    }
}

公共类ExpensesAdapter扩展了RecyclerView.Adapter{
私人ArrayList expenseList；
//类的构造函数
公共支出报表（ArrayList expenseList）{
this.expenseList=expenseList；
}
//获取列表的大小
@凌驾
public int getItemCount（）{
return expenseList==null？0:expenseList.size（）；
}
//指定行布局文件
@凌驾
public ViewHolder onCreateViewHolder（视图组父级，int-viewType）{
View View=LayoutFlater.from（parent.getContext（））.flate（R.layout.row\u item\u视图，parent，false）；
ViewHolder myViewHolder=新的ViewHolder（视图）；
返回myViewHolder；
}
//在每个行元素中加载数据
@凌驾
public void onBindViewHolder（最终视图持有人，最终整型列表位置）{
holder.row_name.setText（expenseList.get（listPosition.getNa（））；
holder.row_amount.setText（expenseList.get（listPosition.getAm（））；
}
//用于初始化行视图的静态内部类
静态类ViewHolder扩展了RecyclerView.ViewHolder{
公共文本查看行名称、行金额；
公共视图持有者（视图项视图）{
超级（项目视图）；
row_name=（TextView）itemView.findViewById（R.id.row_name）；
行金额=（TextView）itemView.findViewById（R.id.row金额）；
}
}
}

---

希望这最终能解决问题。

您声明应用程序崩溃。请编辑您的问题，以包含此类崩溃的整个错误和堆栈跟踪。它将帮助人们给你提供好的答案。你能添加日志堆栈跟踪吗？然后，也许我们可以帮助.java.lang.NullPointerException:尝试在com.example.ojemz.expensetracker.tab1Expenses.expenseData（tab1Expenses.java:34）上的空对象引用上调用虚拟方法“android.text.Editable android.widget.EditText.getText（）在com.example.ojemz.expensetracker.tab1Expenses$2$1.onClick（tab1Expenses.java:81）txtExNa=（txtExName.getText（））.toString（）；哦，对不起，我没有包括在内。让我更新一下问题谢谢。应用程序不再因输入而崩溃，但不会再崩溃