java - Android Studio错误: 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference

Question

这个问题已经有答案了:

What is a NullPointerException, and how do I fix it? (12 个回答)

已关闭 3 年前。

这是错误。我尝试了一些方法，但仍然没有结果。

Process: com.lucastan96.flashchat, PID: 6114
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
    at com.lucastan96.flashchat.ChatListAdapter.getView(__ChatListAdapter.java:101__)
    at android.widget.AbsListView.obtainView(AbsListView.java:2366)
    at android.widget.ListView.makeAndAddView(ListView.java:2052)
    at android.widget.ListView.fillUp(ListView.java:820)
    at android.widget.ListView.layoutChildren(ListView.java:1793)
    at android.widget.AbsListView.onLayout(AbsListView.java:2165)
    at android.view.View.layout(View.java:20672)
    at android.view.ViewGroup.layout(ViewGroup.java:6194)

    boolean isMe = message.getAuthor().equals(mDisplayName);
    setChatRowAppearance(isMe, holder);

    String author = message.getAuthor();
    holder.authorName.setText(author);
    String msg = message.getMessage();
    holder.body.setText(msg);

    return convertView;

第 101 行位于“boolean isMe = message.getAuthor().equals(mDisplayName);”

Answer 1

boolean isMe = message.getAuthor().equals(mDisplayName); 

这里，message.getAuthor() 返回null。你可以通过调试来检查一下解决方案:如果您希望应用程序不崩溃，可以使用 try catch block 示例:

try {
   boolean isMe = message.getAuthor().equals(mDisplayName);
   setChatRowAppearance(isMe, holder);
   String author = message.getAuthor();
   holder.authorName.setText(author);
   String msg = message.getMessage();
   holder.body.setText(msg);
}
catch (Exception e) {}
return convertView;