意图和AlertDialog在片段不能正常工作

Question

我有一个片段，有一些图片，您选择一张图片，然后按下一步转到另一个类来选择朋友。

当您不选择图片时，我想显示一个警告对话框，否则他们应该去选择朋友。

protected TextView mMessage; 
mMessage = (TextView) view.findViewById(R.id.Text); 
final String userMessage = mMessage.getText().toString(); 

mNext = (Button) view.findViewById(R.id.nextButton); 
mNext.setOnClickListener(new View.OnClickListener() { 
    @Override 
    public void onClick(View v) { 
     if (userMessage.equals("") || userMessage.equals(null)) { 
      AlertDialog.Builder builder = new AlertDialog.Builder(messageFragment.this.getActivity()); 
      builder.setTitle("oops"); 
      builder.setMessage("Make sure you take a pic"); 
      builder.setPositiveButton(android.R.string.ok, null); 
      AlertDialog dialog = builder.create(); 
      dialog.show(); 
     } else { 
      //blahh 
     } 
    } 
}); 

即使在文本视图中有文本时，警报对话框也会显示。

Answer 1

之所以错误出现是因为pictureFragment.this是一个片段。它必须是一个活动才能工作，所以试试这个：

private TextView mMessage; 
mMessage = (TextView) view.findViewById(R.id.text); 

//On Button Click... 
@Override 
public void onClick(View v) { 
    String userMessage = mMessage.getText().toString(); 
    if (userMessage.equals(null) || userMessage.equals("") || userMessage.isEmpty()) { 
     AlertDialog.Builder builder = new AlertDialog.Builder(getActivity()); 
     builder.setTitle("oops"); 
     builder.setMessage("Make sure select a pic"); 
     builder.setPositiveButton(android.R.string.ok, null); 
     AlertDialog dialog = builder.create(); 
     dialog.show(); 
    } else { 
     Intent recipientsIntent = new Intent (getActivity(), RecipientsActivity.class); 
     startActivity(recipientsIntent); 
    } 
} 

Answer 2

取出*，并通过改变这样的：

Intent recipientsIntent = new Intent(v.getContext(),RecipientsActivity.class); 
    startActivity(recipientsIntent); 

或

Intent recipientsIntent = new Intent(pictureFragment.this.getActivity(), RecipientsActivity.class.class); 
    startActivity(recipientsIntent); 

Answer 3

Inside Fragments use getActivity（）not this。

试试这个;

Intent recipientsIntent = new Intent(getActivity(),RecipientsActivity.class); 
startActivity(recipientsIntent);