Question

我的主要活动课程：

public class MainActivity extends AppCompatActivity {

    private Button mAddProfileButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mAddProfileButton = (Button) findViewById(R.id.idAddNewProfileButton);
        mAddProfileButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                AlertDialog.Builder alert = new AlertDialog.Builder(MainActivity.this);

                alert.setTitle("Add New Profile");
                alert.setMessage("Name:");

                final EditText input = new EditText(MainActivity.this);
                alert.setView(input);

                alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int whichButton) {
                        // user pressed OK
                        String value = input.getText().toString();
                        Toast.makeText(MainActivity.this, value, Toast.LENGTH_SHORT).show();
                        // do something with the value!
                    }
                });

                alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int whichButton) {
                        // Canceled.
                    }
                });

                alert.show();
            }
        });
    }

    @Override
    protected void onPause() {
        super.onPause();
    }

    @Override
    protected void onResume() {
        super.onResume();
    }
}

因此，基本上在主屏幕上，您可以按一个按钮向我的应用添加新的个人资料。当用户单击按钮时，用户输入对话框显示正常，并且他们可以输入名称，但是如果您旋转屏幕，它将刷新活动并完全取消提示。

有没有办法保留这个？我熟悉OnSaveInstanceState和OnRestoreInstanceState背后的基本思想，但我不知道如何让它记住并重新实例化输入对话框以及用户输入的内容远。

Answer 1

如果您旋转屏幕，它会刷新活动并完全删除提示。

目前还不清楚“提示”是什么。

如果通过“提示”，则表示您的AlertDialog，这是因为您没有使用DialogFragment。将AlertDialog换成DialogFragment，DialogFragment将为您处理配置更改。

在this sample app中，我有DialogFragment创建我的AlertDialog：

/***
  Copyright (c) 2012 CommonsWare, LLC
  Licensed under the Apache License, Version 2.0 (the "License"); you may not
  use this file except in compliance with the License. You may obtain a copy
  of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required
  by applicable law or agreed to in writing, software distributed under the
  License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
  OF ANY KIND, either express or implied. See the License for the specific
  language governing permissions and limitations under the License.

  From _The Busy Coder's Guide to Android Development_
    https://commonsware.com/Android
 */

package com.commonsware.android.dlgfrag;

import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.content.DialogInterface;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class SampleDialogFragment extends DialogFragment implements
    DialogInterface.OnClickListener {
  private View form=null;

  @Override
  public Dialog onCreateDialog(Bundle savedInstanceState) {
    form=
        getActivity().getLayoutInflater()
                     .inflate(R.layout.dialog, null);

    AlertDialog.Builder builder=new AlertDialog.Builder(getActivity());

    return(builder.setTitle(R.string.dlg_title).setView(form)
                  .setPositiveButton(android.R.string.ok, this)
                  .setNegativeButton(android.R.string.cancel, null).create());
  }

  @Override
  public void onClick(DialogInterface dialog, int which) {
    String template=getActivity().getString(R.string.toast);
    EditText name=(EditText)form.findViewById(R.id.title);
    EditText value=(EditText)form.findViewById(R.id.value);
    String msg=
        String.format(template, name.getText().toString(),
                      value.getText().toString());

    Toast.makeText(getActivity(), msg, Toast.LENGTH_LONG).show();
  }

  @Override
  public void onDismiss(DialogInterface unused) {
    super.onDismiss(unused);

    Log.d(getClass().getSimpleName(), "Goodbye!");
  }

  @Override
  public void onCancel(DialogInterface unused) {
    super.onCancel(unused);

    Toast.makeText(getActivity(), R.string.back, Toast.LENGTH_LONG).show();
  }
}

然后，该活动只会显示DialogFragment，在这种情况下由布局中与Button方法关联的showMe()小部件触发：

/***
  Copyright (c) 2012 CommonsWare, LLC
  Licensed under the Apache License, Version 2.0 (the "License"); you may not
  use this file except in compliance with the License. You may obtain a copy
  of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required
  by applicable law or agreed to in writing, software distributed under the
  License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
  OF ANY KIND, either express or implied. See the License for the specific
  language governing permissions and limitations under the License.

  From _The Busy Coder's Guide to Android Development_
    https://commonsware.com/Android
 */

package com.commonsware.android.dlgfrag;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;

public class MainActivity extends Activity {
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
  }

  public void showMe(View v) {
    new SampleDialogFragment().show(getFragmentManager(), "sample");
  }
}

在用户输入过程中如何防止在旋转屏幕时重置

1 个答案: