java - ArrayList getIntent().getStringArrayListExtra

Question

我想从一个 Fragment 获取一个 ArrayList 到另一个，我使用 Intent 方法，如下所示:

我想从中获取它的 fragment

                    Intent intent = new Intent(getActivity(), MainActivity.class);
                intent.putStringArrayListExtra("server_name_list", server_name_list);

如果我调试它，我可以看到我所做的新条目。但是在我使用 getIntent().getStringArrayListExtra 的 Fragment 中，没有新条目。我做错了什么？

这是我使用该方法的 Fragment 中的代码:

/* Server Name Spinner */
        ArrayList<String> server_name_list = getIntent().getStringArrayListExtra("server_name_list");

        if (server_name_list != null) {

            spinner = (Spinner) view.findViewById(R.id.server_spinner);
            ;
            ArrayAdapter<String> server_adapter = new ArrayAdapter<String>(this.getActivity(),
                    android.R.layout.simple_spinner_item, server_name_list);

            server_adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spinner.setAdapter(server_adapter);

            spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

                public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {

                    selected = parent.getItemAtPosition(pos).toString();

                    myWebView.loadUrl(selected);
                }

                public void onNothingSelected(AdapterView<?> parent) {

                }
            });

编辑:整个代码

public class MainActivity extends AppCompatActivity implements AddServerFragment.Callback {

    static WebView myWebView;
    Fragment AddServerFragment, WebViewFragment;
    ArrayList<String> server_name_list;

    @Override
    public ArrayList<String> getArrayListFromActivity() {

        WebViewFragment frag = (WebViewFragment) getSupportFragmentManager().findFragmentByTag("AddServerFragment");
        if (frag != null) {
            server_name_list = frag.getArrayListFromWebViewFragment();
        }
        return server_name_list;
    }

    /* Menu */
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.webview:
                getSupportFragmentManager().beginTransaction()
                        .replace(R.id.container, new WebViewFragment() {

                        })
                        .commit();
                return true;
            case R.id.add_server:
                getSupportFragmentManager().beginTransaction()
                        .replace(R.id.container, new AddServerFragment() {

                        })
                        .commit();
                return true;
            case R.id.menu_refresh:
                myWebView.reload();
                return true;
            default:
                return true;
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (findViewById(R.id.container) != null) {
            if (savedInstanceState != null) {
                return;
            }
            AddServerFragment = new Fragment();
            WebViewFragment = new Fragment();
        }
        getSupportFragmentManager().beginTransaction()
                .replace(R.id.container, new WebViewFragment() {

                })
                .commit();
    }

    /*WebView Fragment*/
    public class WebViewFragment extends Fragment {

        String selected;
        Spinner spinner;

        public WebViewFragment(){
        }

        private Callback callback;

        public interface Callback {
            public ArrayList<String> getArrayListFromActivity();
        }

        @Override
        public void onAttach(Activity activity) {
            callback = (Callback) activity;
        }

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

            /* WebView */
            myWebView = (WebView) view.findViewById(R.id.webView);
            myWebView.setWebViewClient(new WebC());
            WebSettings webSettings = myWebView.getSettings();

            /* JavaScript Enable */
            webSettings.setJavaScriptEnabled(true);

            /* Server Name Spinner */

            ArrayList<String> server_name_list = callback.getArrayListFromActivity();

            if (server_name_list != null) {

                spinner = (Spinner) view.findViewById(R.id.server_spinner);
                ;
                ArrayAdapter<String> server_adapter = new ArrayAdapter<String>(this.getActivity(),
                        android.R.layout.simple_spinner_item, server_name_list);

                server_adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
                spinner.setAdapter(server_adapter);

                spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

                    public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {

                        selected = parent.getItemAtPosition(pos).toString();

                        myWebView.loadUrl(selected);
                    }

                    public void onNothingSelected(AdapterView<?> parent) {

                    }
                });
            }
            return view;
        }
    }

    /*Add Server Fragment*/
    public class AddServerFragment extends Fragment
            implements View.OnClickListener {

        @Override
        public void onClick(View view) {
        }

        public AddServerFragment(){
        }

        Button btn_back, btn_add;
        EditText server_ip, server_name;

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

            server_ip = (EditText) view.findViewById(R.id.edit_server_address);
            server_name = (EditText) view.findViewById(R.id.edit_server_name);

            btn_back = (Button) view.findViewById(R.id.btn_back);
            btn_back.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View view) {
                    getSupportFragmentManager().beginTransaction()
                            .replace(R.id.container, new WebViewFragment() {

                            })
                            .commit();
                }
            });

            btn_add = (Button) view.findViewById(R.id.btn_add);
            btn_add.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View view) {
                    String new_server_ip = null, new_server_name = null;

                    ArrayList<String> server_name_list = new ArrayList<>();
                    ArrayList<String> server_ip_list = new ArrayList<>();

                    new_server_ip = server_ip.getText().toString();
                    server_ip_list.add(new_server_ip);

                    new_server_name = server_name.getText().toString();
                    server_name_list.add(new_server_name);
                }
            });

            return view;
        }
    }

    /* WebView Client */
    public class WebC extends WebViewClient {

        @Override
        public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {

            super.onReceivedError(view, errorCode, description, failingUrl);

        }
    }
}

Answer 1

您可以将 ArrayList 存储为容器 Activity 的成员变量:

private ArrayList<String> server_name_list;

添加 setter/getter :

public ArrayList<String> getArrayList() {
    return server_name_list;
}

在您的 fragment 中，您可以这样访问它:(假设容器 Activity 的名称是 MainActivity)

ArrayList<String> arraylist = ((MainActivity)getActivity()).getArrayList();