java - 如何将 ArrayList 数据设置到扩展 listView 的另一个 fragment 中的 ListView 中？

Question

如何将ArrayList数据设置到另一个扩展listView的 fragment 中的ListView？

非常感谢各位专家的帮助。

自定义 ArrayList 接受 int、string、string。我从两个 EditText 获取用户输入并将它们添加到此 ArrayList 中。当用户重新进入时，它应该继续将其添加到ArrayList中。

目标是获取用户的所有条目并将其显示在下一个 fragment 的 ListView 中。但只有将ArrayList中的两个String转换为String数组才能用作ArrayAdapter的数据源。因此重写了 diarylogs 类中的 toSting 方法。我可以在 sysout 时看到 ArrayList 中的值。但是，一旦我设置ListAdapter，应用程序就会崩溃。无法理解我做错了什么。

更新

Class MainActivity extends Activity

//Static variable
public static ArrayList<DiaryLogs> test;
public static int Monday=0;

类日记日志

public class DiaryLogs {

    String timeEntry, entryEntered;
    int day;

    // single constructor that takes an integer and two string
    public DiaryLogs(int day, String timeEntry, String entryEntered) {
        super();
        this.day = day;
        this.timeEntry = timeEntry;
        this.entryEntered = entryEntered;

    }

    public String getTimeEntry() {
        return timeEntry;
    }

    public void setTimeEntry(String timeEntry) {
        this.timeEntry = timeEntry;
    }

    public String getEntryEntered() {
        return entryEntered;
    }

    public void setEntryEntered(String entryEntered) {
        this.entryEntered = entryEntered;
    }

    public int getDay() {
        return day;
    }

    public void setDay(int day) {
        this.day = day;
    }

    @Override
    public String toString() {

        return timeEntry + "\n" + entryEntered;


    }
}

Monday_fragment 类

public class Monday_fragment extends Fragment {

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        return inflater.inflate(R.layout.monday_fragment, container, false);

    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        currentDateTime();
        super.onViewCreated(view, savedInstanceState);

    }

    public void currentDateTime() {
        EditText timeText = (EditText) getView().findViewById(
                R.id.dateTimeEText);
        SimpleDateFormat df = new SimpleDateFormat("d/M/yyyy:H:m");
        String dateTime = df.format(Calendar.getInstance().getTime());
        timeText.setText(dateTime);
    }

    @Override
    public void onStart() {

        Button saveBtn = (Button) getView()
                .findViewById(R.id.saveDiaryEntryBtn);
        saveBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                EditText timeText = (EditText) getView().findViewById(
                        R.id.dateTimeEText);

                EditText entryText = (EditText) getView().findViewById(
                        R.id.diaryEntryEText);
                String timeEntry = timeText.getText().toString();

                String entryEntered = entryText.getText().toString();

                MainActivity.test = new ArrayList<DiaryLogs>();

                MainActivity.test.add(new DiaryLogs(MainActivity.Monday,
                        timeEntry, entryEntered));

            }

        }

        );

        Button showBtn = (Button) getView().findViewById(
                R.id.showDiaryEntriesBtn);
        showBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                FragmentManager fragmentManager = getFragmentManager();
                FragmentTransaction fragmentTransaction = fragmentManager
                        .beginTransaction();
                Monday_list_fragment mlf = new Monday_list_fragment();
                fragmentTransaction.replace(android.R.id.content, mlf);
                fragmentTransaction.commit();

            }
        });

        super.onStart();
    }

}

Monday_list_fragment 类

public class Monday_list_fragment extends ListFragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        // TODO Auto-generated method stub

        return inflater
                .inflate(R.layout.monday_list_fragment, container, false);

    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {

        super.onViewCreated(view, savedInstanceState);


    }

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

System.out.println(MainActivity.test); //test: if value can be seen

        ArrayAdapter<DiaryLogs> arrayAdapter = new ArrayAdapter<DiaryLogs>(
                getActivity(), 
                android.R.layout.simple_list_item_1, MainActivity.test
                );
        setListAdapter(arrayAdapter); //once i set adapter it crashes

    }

}

布局 XML 文件:monday_list_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <ListView
        android:id="@id/android:list"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:smoothScrollbar="true" >
    </ListView>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true" >

        <Button
            android:id="@+id/returnBtn"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/return_mon_Btn" 
            android:onClick="monClick">
        </Button>
    </LinearLayout>
</RelativeLayout>

LOGCAT

04-11 23:45:53.992: E/AndroidRuntime(10006): FATAL EXCEPTION: main
04-11 23:45:53.992: E/AndroidRuntime(10006): Process: com.example.s0217980_diary, PID: 10006
04-11 23:45:53.992: E/AndroidRuntime(10006): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.s0217980_diary/com.example.s0217980_diary.MainActivity}: android.view.InflateException: Binary XML file line #41: Error inflating class fragment
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.ActivityThread.access$800(ActivityThread.java:135)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.os.Handler.dispatchMessage(Handler.java:102)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.os.Looper.loop(Looper.java:136)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.ActivityThread.main(ActivityThread.java:5017)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at java.lang.reflect.Method.invokeNative(Native Method)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at java.lang.reflect.Method.invoke(Method.java:515)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at dalvik.system.NativeStart.main(Native Method)
04-11 23:45:53.992: E/AndroidRuntime(10006): Caused by: android.view.InflateException: Binary XML file line #41: Error inflating class fragment
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.Activity.setContentView(Activity.java:1929)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at com.example.s0217980_diary.MainActivity.onCreate(MainActivity.java:52)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.Activity.performCreate(Activity.java:5231)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
04-11 23:45:53.992: E/AndroidRuntime(10006):    ... 11 more
04-11 23:45:53.992: E/AndroidRuntime(10006): Caused by: java.lang.NullPointerException
04-11 23:45:53.992: E/AndroidRuntime(10006):    at com.example.s0217980_diary.Monday_list_fragment.onCreate(Monday_list_fragment.java:45)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.Fragment.performCreate(Fragment.java:1678)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:859)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1040)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1142)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.app.Activity.onCreateView(Activity.java:4786)
04-11 23:45:53.992: E/AndroidRuntime(10006):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:689)
04-11 23:45:53.992: E/AndroidRuntime(10006):    ... 21 more
04-11 23:48:11.294: D/dalvikvm(10069): GC_FOR_ALLOC freed 71K, 6% free 3267K/3448K, paused 16ms, total 24ms
04-11 23:48:11.364: D/AndroidRuntime(10069): Shutting down VM
04-11 23:48:11.364: W/dalvikvm(10069): threadid=1: thread exiting with uncaught exception (group=0xb0c9db20)
04-11 23:48:11.374: E/AndroidRuntime(10069): FATAL EXCEPTION: main
04-11 23:48:11.374: E/AndroidRuntime(10069): Process: com.example.s0217980_diary, PID: 10069
04-11 23:48:11.374: E/AndroidRuntime(10069): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.s0217980_diary/com.example.s0217980_diary.MainActivity}: android.view.InflateException: Binary XML file line #41: Error inflating class fragment
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.ActivityThread.access$800(ActivityThread.java:135)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.os.Handler.dispatchMessage(Handler.java:102)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.os.Looper.loop(Looper.java:136)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.ActivityThread.main(ActivityThread.java:5017)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at java.lang.reflect.Method.invokeNative(Native Method)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at java.lang.reflect.Method.invoke(Method.java:515)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at dalvik.system.NativeStart.main(Native Method)
04-11 23:48:11.374: E/AndroidRuntime(10069): Caused by: android.view.InflateException: Binary XML file line #41: Error inflating class fragment
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.Activity.setContentView(Activity.java:1929)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at com.example.s0217980_diary.MainActivity.onCreate(MainActivity.java:52)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.Activity.performCreate(Activity.java:5231)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
04-11 23:48:11.374: E/AndroidRuntime(10069):    ... 11 more
04-11 23:48:11.374: E/AndroidRuntime(10069): Caused by: java.lang.NullPointerException
04-11 23:48:11.374: E/AndroidRuntime(10069):    at com.example.s0217980_diary.Monday_list_fragment.onCreate(Monday_list_fragment.java:45)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.Fragment.performCreate(Fragment.java:1678)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:859)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1040)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1142)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.app.Activity.onCreateView(Activity.java:4786)
04-11 23:48:11.374: E/AndroidRuntime(10069):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:689)
04-11 23:48:11.374: E/AndroidRuntime(10069):    ... 21 more

Answer 1

如果你有一个像 ArrayList 这样的数组，你不需要解压它并提取你想要的字符串并将其添加到另一个数组中，只是为了将其输入到 ListView 中。只需重写 DiaryLogs 类中的 toString() 方法并使用您选择的字符串(例如 timeEntry 和 entryEntered)返回它。喜欢

// class DiaryLogs
class DiaryLogs {
    ...
    @Override
    public toString() {
        return dateTime + " - " + entryName;
    }
    ...
}

// in your activity
ArrayList<DiaryLogs> diaryLogs = new ArrayList<DiaryLogs>();
diaryLogs.add(new DiaryLogs(1, "Apr. 14, 2014", "Entry 1"));
diaryLogs.add(new DiaryLogs(1, "Apr. 14, 2014", "Entry 2"));
diaryLogs.add(new DiaryLogs(1, "Apr. 14, 2014", "Entry 3"));

yourListView.setAdapter(new ArrayAdapter(this, android.R.layout.simple_list_item_1, diaryLogs));

yourListView 显然是您正在使用的 ListView 。