如何解決Textview setText（）在空對象引用上

Question

所以我得到這個錯誤：

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference

我運行了調試工具，這些行為空：

TextView leftMessageView = (TextView) row.findViewById(R.id.leftmsgr);
leftMessageView.setText(Servermessage);

這是它來自的功能：

public View getView(int position, View convertView, @NonNull ViewGroup parent) {

    View row;
    LayoutInflater inflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    ChMessage chMessageObj = getItem(position);
    if (chMessageObj.left) {
        row = inflater.inflate(R.layout.leftmessage, parent, false);
    }else{
        row = inflater.inflate(R.layout.rightmessage, parent, false);
    }

        TextView rightMessageView = (TextView) row.findViewById(R.id.rightmsgr);
        TextView leftMessageView = (TextView) row.findViewById(R.id.leftmsgr);
        rightMessageView.setText(chMessageObj.message);
        leftMessageView.setText(Servermessage);

    return row;
}

不知道為什么它不為空？

任何幫助將是巨大的！

謝謝

Answer 1

嘗試使用以下代碼修復NullPointerException ：

public View getView(int position, View convertView, @NonNull ViewGroup parent) 
{   
    View row;
    LayoutInflater inflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    ChMessage chMessageObj = getItem(position);
    if (chMessageObj.left) {
        row = inflater.inflate(R.layout.leftmessage, parent, false);
    }else{
        row = inflater.inflate(R.layout.rightmessage, parent, false);
    }

        TextView rightMessageView = (TextView) row.findViewById(R.id.rightmsgr);
        TextView leftMessageView = (TextView) row.findViewById(R.id.leftmsgr);
        if (rightMessageView!=null) {
          rightMessageView.setText(chMessageObj.message);
        }
        if (leftMessageView!=null) {
          leftMessageView.setText(Servermessage);
        }

    return row;
}

然后，如果TextView為null是否正確，我就不知道。 檢查您的XML布局。 希望能幫助到你。