Java 我在Android Studio中刷入微粒类后如何显示自动警报对话框？

我想显示对话框/弹出窗口，显示给用户的消息，显示请用一个输入按钮输入您的姓名。点击按钮进入数据库显示信息。如果输入的用户名错误，则应弹出错误消息。 有人能帮我吗？我想在刷卡进入微粒类时自动显示对话框/弹出窗口

这里的主要问题是我已经将我的类扩展到了

Fragment

，现在对于Dialog，我应该扩展另一个类

DialogFragment

，但在一个类中，我只能扩展一个类。 请帮帮我

主要活动

{

Credit.java代码

package com.example.jawa.pops;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * Created by jawa on 10/4/2015.
 */
public class Credit extends Fragment {
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.credit, container, false);

    }
}

现在，当我打开credit.java时，我想自动显示一个对话框

package com.example.jawa.pops;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;  
import android.view.View;    
import android.view.ViewGroup;

public class Credit extends Fragment implements CreditDialog.Callback{

MainActivity mActivity;

@Override
public void onAttach(Activity activity)
{
    super.onAttach(activity);
    try
    {
        mActivity = (MainActivity)activity;
    }
    catch(ClassCastException e)
    {
        Log.e("Credit", "ClassCastException e", e);
    }
}
@Override
public void onStart()
{
super.onStart();
if(mActivity !=null){
CreditDialog dialog = new CreditDialog();
dialog.setTargetFragment(this, 1); 
mActivity.showDialog(dialog);
}
}
@Override
public void onEnterPressed(String name)
{
    //manage answer
}
}

下面是CreditDialog类：

public class CreditDialog extends DialogFragment implements View.OnClickListener
 {
 private EditText mEditText;
 private Button enterButton;

public static interface Callback
{
    public void onEnterPressed(String name);
}

public CreditDialog()
{
    // Empty constructor required for DialogFragment
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
    View view = inflater.inflate(R.layout.dialogfragment, container);
    mEditText =(EditText) view.findViewById(R.id.name);
    enterButton = (Button) view.findViewById(R.id.enterButton);
    enterButton.setOnClickListener(this);
    getDialog().setTitle(R.string.dialog_title);
    return view;
}

@Override
public void onClick(View v)
{
    Callback callback = null;
    try
    {
        callback = (Callback) getTargetFragment();
    }
    catch (ClassCastException e)
    {
        Log.e(this.getClass().getSimpleName(), "Callback of this class must be implemented by target fragment!", e);
        throw e;
    }

    if (callback != null)
    {
       String name="";
            if(mEditText !=null) {
             name=mEditText.getText().toString();
            }
            callback.onEnterPressed(name);
            this.dismiss();
    }
}
}

---

请发布您迄今为止尝试过的代码。只需在

main活动的
onResume
中打开
AlertDialog
，因为
Credit
是滑块的第一个
视图
public class CreditDialog extends DialogFragment implements View.OnClickListener
 {
 private EditText mEditText;
 private Button enterButton;

public static interface Callback
{
    public void onEnterPressed(String name);
}

public CreditDialog()
{
    // Empty constructor required for DialogFragment
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
    View view = inflater.inflate(R.layout.dialogfragment, container);
    mEditText =(EditText) view.findViewById(R.id.name);
    enterButton = (Button) view.findViewById(R.id.enterButton);
    enterButton.setOnClickListener(this);
    getDialog().setTitle(R.string.dialog_title);
    return view;
}

@Override
public void onClick(View v)
{
    Callback callback = null;
    try
    {
        callback = (Callback) getTargetFragment();
    }
    catch (ClassCastException e)
    {
        Log.e(this.getClass().getSimpleName(), "Callback of this class must be implemented by target fragment!", e);
        throw e;
    }

    if (callback != null)
    {
       String name="";
            if(mEditText !=null) {
             name=mEditText.getText().toString();
            }
            callback.onEnterPressed(name);
            this.dismiss();
    }
}
}