Question

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btnScan = (Button)findViewById(R.id.scan);
    listViewIp = (ListView)findViewById(R.id.listviewip);
    bar = (ProgressBar) findViewById(R.id.pbar);
    bar.setVisibility(View.INVISIBLE);

    ipList = new ArrayList();
    adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, android.R.id.text1, ipList);
    listViewIp.setAdapter(adapter);

    btnScan.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            new ScanIpTask().execute();
        }
    });

将其转换为片段

ArrayList ipList; ArrayAdapter适配器;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_scan_ip, container, false);

    btnScan = (Button)rootView.findViewById(R.id.scan);
    listViewIp = (ListView)rootView.findViewById(R.id.listviewip);
    bar = (ProgressBar) rootView.findViewById(R.id.pbar);
    bar.setVisibility(View.INVISIBLE);

    ipList = new ArrayList();
    adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, android.R.id.text1, ipList);
    listViewIp.setAdapter(adapter);

    btnScan.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            new ScanIpTask().execute();
        }
    });


    return rootView;
}

它显示此行中的错误

adapter = new ArrayAdapter（这个， android.R.layout.simple_list_item_1，android.R.id.text1，ipList）;

Answer 1

ArrayAdapter构造函数的第一个参数是Context。 Fragment 不是Context的孩子。您需要传递父Context的{{1}}。

ArrayAdapter（Context context，int resource，int textViewResourceId）

使用Activity获取父活动的上下文。

getActivity()

 adapter = new ArrayAdapter<String>(getActivity(),
        android.R.layout.simple_list_item_1, android.R.id.text1, ipList);
listViewIp.setAdapter(adapter);

内的{p> getActivity()可以返回null，有时会导致片段尚未附加。要清除概念，请阅读This post或类似内容。

Answer 2

用

替换代码

adapter = new ArrayAdapter(getActivity(), android.R.layout.simple_list_item_1, android.R.id.text1, ipList);

将活动转换为片段它会在阵列适配器上显示一些错误

2 个答案: