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在我的应用程序中，我使用 Android 自定义视图来显示一些日志信息。在该视图中，我想根据某些标准更改项目的颜色。我尝试使用以下代码导致 getView 中出现 NullPointerException。

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    try {
        View row = convertView;
        ItemHolder holder = null;

        if( row == null ){
            LayoutInflater inflater = ((Activity)context).getLayoutInflater();
            row = inflater.inflate(layoutResouceId, parent, false);

            holder = new ItemHolder();
            holder.imgIcon = (ImageView)row.findViewById(R.id.imgIcon);
            holder.txtPhoneno = (TextView)row.findViewById(R.id.lvphoneno);
            holder.txtDateTime = (TextView)row.findViewById(R.id.lvdatetime);
            holder.txtSerialno = (TextView)row.findViewById(R.id.lvserialno);
            holder.txtStatus = (TextView)row.findViewById(R.id.lvstatus);

            row.setTag(holder);
        }
        else {
            holder = (ItemHolder)row.getTag();
        }

        MyListViewItem item = items.get(position);
        holder.imgIcon.setImageResource(item.icon);
        holder.txtPhoneno.setText(item.phoneno);
        holder.txtDateTime.setText(item.datetime);
        holder.txtSerialno.setText(item.serialno);

        if( !item.status.isEmpty()){
            if( -1 != item.status.indexOf("OK"))
                holder.txtStatus.setTextColor(Color.GREEN);
            else
                holder.txtStatus.setTextColor(Color.RED);
        }

        holder.txtStatus.setText(item.status);
        return row;         
    }
    catch (Exception e) {
        Helper.Log(getContext(), e.toString());
    }
    return null;
}

但有趣的是，当我删除下面的行时它工作正常

        if( !item.status.isEmpty()){
            if( -1 != item.status.indexOf("OK"))
                holder.txtStatus.setTextColor(Color.GREEN);
            else
                holder.txtStatus.setTextColor(Color.RED);
        }

日志猫

    12-15 07:04:49.668: E/AndroidRuntime(331): FATAL EXCEPTION: main
    12-15 07:04:49.668: E/AndroidRuntime(331): java.lang.NullPointerException
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.AbsListView.obtainView(AbsListView.java:1432)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.ListView.makeAndAddView(ListView.java:1745)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.ListView.fillDown(ListView.java:670)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.ListView.fillSpecific(ListView.java:1302)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.ListView.layoutChildren(ListView.java:1576)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.AbsListView.onLayout(AbsListView.java:1260)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.view.View.layout(View.java:7175)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1254)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1130)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.LinearLayout.onLayout(LinearLayout.java:1047)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.view.View.layout(View.java:7175)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.FrameLayout.onLayout(FrameLayout.java:338)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.view.View.layout(View.java:7175)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1254)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1130)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.LinearLayout.onLayout(LinearLayout.java:1047)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.view.View.layout(View.java:7175)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.widget.FrameLayout.onLayout(FrameLayout.java:338)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.view.View.layout(View.java:7175)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.view.ViewRoot.performTraversals(ViewRoot.java:1140)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1859)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.os.Handler.dispatchMessage(Handler.java:99)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.os.Looper.loop(Looper.java:123)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at android.app.ActivityThread.main(ActivityThread.java:3683)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at java.lang.reflect.Method.invokeNative(Native Method)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at java.lang.reflect.Method.invoke(Method.java:507)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
    12-15 07:04:49.668: E/AndroidRuntime(331):  at dalvik.system.NativeStart.main(Native Method)

请帮我解决这个问题

谢谢

4

1 回答 1

1

我敢打赌那status是空的：

if( -1 != item.status.indexOf("OK"))

item显然不是 null 并且假设它holder.txtStatus.setText()也不会抛出 NPE，这只会留下status......

（但如果没有更多信息，我无法帮助您。）

于 2012-12-15T00:53:25.857 回答