将TextView设置为Visible时java崩溃

1 周，5 日 Questions & Answers 181

当设置文本视图在我的片段中可见时，我的应用程序崩溃

在onCreateView中，我在setVisibility（）上有一个NullPointerException

settingsTitle = (TextView)getActivity().findViewById(R.id.settingsTitle);
settingsTitle.setVisibility(View.VISIBLE);

下面是xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
    安卓:layout_width="match_parent"
    安卓:layout_height="match_parent"
    安卓:background="@color/plain_background">

    <TextView
        安卓:id="@+id/settingsTitle"
        安卓:layout_width="match_parent"
        安卓:layout_height="50dp"
        安卓:layout_centerHorizontal="true"
        安卓:text="Choose Your Default Screen"
        安卓:textAlignment="center"
        安卓:gravity="center"
        安卓:textColor="@color/black_text"
        安卓:visibility="gone"/>

    <ListView
        安卓:id="@+id/listFeed"
        安卓:layout_width="fill_parent"
        安卓:layout_height="wrap_content"
        安卓:layout_below="@id/settingsTitle"
        安卓:fadeScrollbars="true"
        安卓:fastScrollEnabled="true"
        安卓:fadingEdge="none"
        安卓:divider="@color/kfb_blue"
        安卓:dividerHeight="1dp"
        安卓:background="@color/plain_background"/>

</RelativeLayout>

以下是我片段中所需的所有代码

package kyfb.安卓.kyfb.com.kyfb;

import 安卓.app.Fragment;
import 安卓.content.Context;
import 安卓.content.SharedPreferences;
import 安卓.graphics.Color;
import 安卓.os.Bundle;
import 安卓.view.LayoutInflater;
import 安卓.view.View;
import 安卓.view.ViewGroup;
import 安卓.widget.AdapterView;
import 安卓.widget.ArrayAdapter;
import 安卓.widget.ListView;
import 安卓.widget.TextView;


public class SettingsFragment extends Fragment {

    private ListView defaultScreen;
    private static SharedPreferences sharedPref;
    private static SharedPreferences.Editor editor;
    private static TextView settingsTitle;

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        super.onCreateView(inflater, container, savedInstanceState);
        View rootView = inflater.inflate(R.layout.fragment_benefits, null);

        // this.getActivity().getActionBar().setTitle("Choose Default Screen");

        String[] values = new String[] {"Ag News", "Action Alerts", "Market Updates", "KFB Magazine", "Ag Facts",
                 "Member Benefits", "Roadside Farm Markets", "Media", "Annual Meeting", "My KYFB"};

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity().getApplicationContext(), 安卓.R.layout.simple_list_item_single_choice, 安卓.R.id.text1, values) {
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                View view = super.getView(position, convertView, parent);
                TextView text = (TextView) view.findViewById(安卓.R.id.text1);
                text.setTextColor(getResources().getColor(R.color.kfb_blue));
                return view;
            }
        };

        defaultScreen = (ListView)rootView.findViewById(R.id.listFeed);
        defaultScreen.setChoiceMode(defaultScreen.CHOICE_MODE_SINGLE);
        defaultScreen.setAdapter(adapter);

        settingsTitle = (TextView)getActivity().findViewById(R.id.settingsTitle);
        settingsTitle.setVisibility(View.VISIBLE);

        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
        String savedDefault = sharedPref.getString("DEFAULT", null);
        if (savedDefault != null) {
            if (savedDefault.equals("ag news")) {
                defaultScreen.setItemChecked(0, true);
            }
            else if (savedDefault.equals("action alerts")) {
                defaultScreen.setItemChecked(1, true);
            }
            else if (savedDefault.equals("market updates")) {
                defaultScreen.setItemChecked(2, true);
            }
            else if (savedDefault.equals("kfb magazine")) {
                defaultScreen.setItemChecked(3, true);
            }
            else if (savedDefault.equals("ag facts")) {
                defaultScreen.setItemChecked(4, true);
            }
            else if (savedDefault.equals("member benefits")) {
                defaultScreen.setItemChecked(5, true);
            }
            else if (savedDefault.equals("roadside markets")) {
                defaultScreen.setItemChecked(6, true);
            }
            else if (savedDefault.equals("media")) {
                defaultScreen.setItemChecked(7, true);
            }
            else if (savedDefault.equals("annual meeting")) {
                defaultScreen.setItemChecked(8, true);
            }
            else if (savedDefault.equals("my kyfb")) {
                defaultScreen.setItemChecked(9, true);
            }
        }
        else {
            defaultScreen.setItemChecked(0, true);
        }

        defaultScreen.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                switch(position) {
                    case 0:
                        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
                        editor = sharedPref.edit();
                        editor.putString("DEFAULT", "ag news");
                        editor.apply();

                        defaultScreen.setItemChecked(0, true);
                        break;
                    case 1:
                        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
                        editor = sharedPref.edit();
                        editor.putString("DEFAULT", "action alerts");
                        editor.apply();

                        defaultScreen.setItemChecked(1, true);
                        break;
                    case 2:
                        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
                        editor = sharedPref.edit();
                        editor.putString("DEFAULT", "market updates");
                        editor.apply();

                        defaultScreen.setItemChecked(2, true);
                        break;
                    case 3:
                        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
                        editor = sharedPref.edit();
                        editor.putString("DEFAULT", "kfb magazine");
                        editor.apply();

                        defaultScreen.setItemChecked(3, true);
                        break;
                    case 4:
                        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
                        editor = sharedPref.edit();
                        editor.putString("DEFAULT", "ag facts");
                        editor.apply();

                        defaultScreen.setItemChecked(4, true);
                        break;
                    case 5:
                        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
                        editor = sharedPref.edit();
                        editor.putString("DEFAULT", "member benefits");
                        editor.apply();

                        defaultScreen.setItemChecked(5, true);
                        break;
                    case 6:
                        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
                        editor = sharedPref.edit();
                        editor.putString("DEFAULT", "roadside markets");
                        editor.apply();

                        defaultScreen.setItemChecked(6, true);
                        break;
                    case 7:
                        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
                        editor = sharedPref.edit();
                        editor.putString("DEFAULT", "media");
                        editor.apply();

                        defaultScreen.setItemChecked(7, true);
                        break;
                    case 8:
                        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
                        editor = sharedPref.edit();
                        editor.putString("DEFAULT", "annual meeting");
                        editor.apply();

                        defaultScreen.setItemChecked(8, true);
                        break;
                    case 9:
                        sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
                        editor = sharedPref.edit();
                        editor.putString("DEFAULT", "my kyfb");
                        editor.apply();

                        defaultScreen.setItemChecked(9, true);
                        break;
                    default:
                        break;
                }
            }
        });

        return rootView;
    }
}

共 (2) 个答案

# 1 楼答案

问题是因为我使用了getActivity.findViewById()而不是rootView.findViewById()
# 2 楼答案
你从哪里打电话来的？我假设您使用片段是因为“getActivity（）”部分

这里发生了两件事中的一件：
1. getAtivity（）为null，如果您的片段尚未附加到活动，则可能会发生这种情况。可以通过在if语句中围绕代码来解决这个问题：
```
if(isAdded()){
    settingsTitle = (TextView)getActivity().findViewById(R.id.settingsTitle);
    settingsTitle.setVisibility(View.VISIBLE);
}
```
2. 您的布局尚未膨胀，因此屏幕上还没有带有“settingsTitle”id的视图。如果您是从onCreateActivity调用此代码，那么应该引用新添加的视图，而不是getActivity（）。findView
需要更多的代码来提供具体的解决方案

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将TextView设置为Visible时java崩溃

共 (2) 个答案

# 1 楼答案

# 2 楼答案