Question

我无法弄清楚这个问题，我没有任何信息会发生什么！我从谷歌应用程序面板中收到此错误。请勿参考此内容。

这是google发布中的错误：

 java.lang.RuntimeException: Unable to start activity     
     ComponentInfo{es.project/es.project.activity.ChatActivity}: java.lang.NullPointerException
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
    at android.app.ActivityThread.access$600(ActivityThread.java:123)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4424)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:817)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
    at dalvik.system.NativeStart.main(Native Method)
    Caused by: java.lang.NullPointerException
    at es.project.activity.ChatActivity.onCreate(Unknown Source)
    at android.app.Activity.performCreate(Activity.java:4470)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
    ... 11 more

在我的模拟器中，此代码有效，但我认为有些人有错误。这是我的OnCreate：

@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    serverId = getIntent().getExtras().getInt("serverId");
    server = Chatsi.getInstance().getServerById(serverId);
    Settings settings = new Settings(this);
    ActionBar actionBar = getSupportActionBar();
    actionBar.setDisplayHomeAsUpEnabled(false);
    setTitle("");
    setContentView(R.layout.chat);        
    EditText input = (EditText) findViewById(R.id.input);
    input.setOnKeyListener(inputKeyListener);
    //INDICATOR
    pager = (ViewPager) findViewById(R.id.pager);
    pagerAdapter = new ConversationPagerAdapter(this, server);
    pager.setAdapter(pagerAdapter);
    final float density = getResources().getDisplayMetrics().density;
    indicator = (ConversationIndicator) findViewById(R.id.titleIndicator);
    indicator.setServer(server);
    indicator.setTypeface(Typeface.DEFAULT);
    indicator.setViewPager(pager);
    indicator.setFooterColor(0xFFFF8800);
    indicator.setFooterLineHeight(2 * density);
    indicator.setFooterIndicatorHeight(4 * density);
    indicator.setFooterIndicatorStyle(IndicatorStyle.Underline);
    indicator.setSelectedColor(0xFF000000);
    indicator.setSelectedBold(true);
    indicator.setBackgroundColor(0xFFF2F2F2);
    indicator.setTextColor(0xFF222222);
    //Botones
    Button boton1 = (Button) this.findViewById(R.id.enviar);
    boton1.setOnClickListener(mandartexto); 
    Button boton2 = (Button) this.findViewById(R.id.emoticonos);
    boton2.setOnClickListener(mandaremoticon); 
    Button boton3 = (Button) this.findViewById(R.id.lupa);
    boton3.setOnClickListener(mandarlupa); 
    //MENUS
    menuview = (ListView) findViewById(R.id.menuview);
    MenuAdapter menuAdapter = new MenuAdapter(this, BOTONES);
    menuview.setAdapter(menuAdapter); 

    historySize = settings.getHistorySize();

    if (server.getStatus() == Status.PRE_CONNECTING) {
        server.clearConversations();
        pagerAdapter.clearConversations();
        server.getConversation(ServerInfo.DEFAULT_NAME).setHistorySize(historySize);
    }

    float fontSize = settings.getFontSize();
    indicator.setTextSize(fontSize * density);

    input.setTextSize(settings.getFontSize());
    input.setTypeface(Typeface.DEFAULT);

    // Optimization : cache field lookups
    Collection<Conversation> mConversations = server.getConversations();

    for (Conversation conversation : mConversations) {
        // Only scroll to new conversation if it was selected before
        if (conversation.getStatus() == Conversation.STATUS_SELECTED) {
            onNewConversation(conversation.getName());
        } else {
            createNewConversation(conversation.getName());
        }
    }

    scrollback = new Scrollback();
    this.overridePendingTransition(R.anim.appear,R.anim.disappear);

}

Answer 1

server = Chatsi.getInstance().getServerById(serverId);

然后

if (server.getStatus() == Status.PRE_CONNECTING) {

形成一个潜在的很多例子的地方，其中一个无法获得对象的微不足道的事情（由于暂时信号强度暂时不良而导致）有可能导致未被捕获的空指针异常。

每当您从一个可能失败的机制获得一个对象时，您应该在使用它之前检查该对象是否为非空，或者保护您尝试通过try / catch使用它块或更高级别的处理程序，可以从异常中恢复。

问题不一定与您的服务器对象有关 - 它可能是您的视图或其他任何通过可能失败的机制获取，或在代码路径中使用的尚未初始化。

java.lang.NullPointerException（未知来源）

1 个答案: