在传递Android DialogFragment参数时,onCreateDialog bundle agument意外地为null

Question

我正在尝试使用DialogFragment在Android中显示一个基本对话框,使用对话框消息的参数,如StackOverflow线程和DialogFragment文档中所述.我的问题是onCreateDialog中的Bundle参数savedInstanceState始终显示为null,这意味着该活动显示一个空对话框而不是带有消息的对话框.如何从newInstance工厂方法获取非null的bundle内容以显示在onCreateDialog中？或者我只是遗漏了别的东西？

我从文档中看到的唯一重要区别是我使用的是非静态类.我希望积极的对话框按钮取决于消息的内容,所以这是故意的.

import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.content.DialogInterface;
import android.os.Bundle;

public class SampleDialog extends DialogFragment {
    public static final String DIALOG_MESSAGE = "dialogMessage";

    private String dialogMessage;

    // arguments are handled through factory method with bundles for lifecycle maintenance
    public SampleDialog(){
    }

    public static SampleDialog newInstance(String dialogMessage){
        SampleDialog fragment = new SampleDialog();
        Bundle args = new Bundle();
        args.putString(DIALOG_MESSAGE, dialogMessage);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        if(savedInstanceState != null) {
            dialogMessage = savedInstanceState.getString(DIALOG_MESSAGE);
        }

        // Use the Builder class for convenient dialog construction
        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        builder.setMessage(dialogMessage)
                .setPositiveButton(R.string.dial, new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        // will depend on content of dialogMessage
                    }
                })
                .setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        // User cancelled the dialog
                    }
                });
        // Create the AlertDialog object and return it
        return builder.create();
    }
}

我通过这种方式从一个活动中调用它:

SampleDialog myDialog = SampleDialog.newInstance("does not appear");
FragmentTransaction transaction = getFragmentManager().beginTransaction();
myDialog.show(transaction, TAG);

Answer 1

你必须用来getArguments检索Bundle你设置的setArguments

代替

if(savedInstanceState != null) {
     dialogMessage = savedInstanceState.getString(DIALOG_MESSAGE);
}

你应该有类似的东西:

Bundle bundle = getArguments();
if (bundle != null) {
    dialogMessage = bundle.getString(DIALOG_MESSAGE);
}