已添加java片段

Question

我有3个片段和3个按钮，当我点击一个按钮时，它会改变片段，但当我点击片段列表上的一个项目时，它会打开一个新片段

public class MainActivity extends FragmentActivity implements ContactFragment.OnContactClickedListener{
private CalendarFragment calendarFragment;
private CommunicationFragment communicationFragment;
private ContactFragment contactFragment;
private SingleContactFragment singleContactFragment;
//
private FragmentManager manager;
//
private Button btn_calendar, btn_contact, btn_communication;

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

    manager = getSupportFragmentManager();
    manager.beginTransaction()
            .add(R.id.fl_main_container, calendarFragment).commit();
}

private void bind() {
    btn_calendar = (Button) findViewById(R.id.btn_main_calendar);
    btn_communication = (Button) findViewById(R.id.btn_main_communication);
    btn_contact = (Button) findViewById(R.id.btn_main_contact);
    btn_calendar.setOnClickListener(listener);
    btn_communication.setOnClickListener(listener);
    btn_contact.setOnClickListener(listener);
}

private void initFragments() {
    calendarFragment = new CalendarFragment();
    communicationFragment = new CommunicationFragment();
    contactFragment = new ContactFragment();
    singleContactFragment = new SingleContactFragment();
}

private void changeFragment(Fragment f) {
    manager.beginTransaction().replace(R.id.fl_main_container, f).commit();
    manager.executePendingTransactions();
}
private void displayContact(ContactObject contact){
    manager.beginTransaction().replace(R.id.fl_main_container, singleContactFragment).addToBackStack(null).commit();
    manager.executePendingTransactions();
}
private OnClickListener listener = new OnClickListener() {

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch (v.getId()) {
        case R.id.btn_main_calendar:
            changeFragment(calendarFragment);
            break;
        case R.id.btn_main_communication:
            changeFragment(communicationFragment);
            break;
        case R.id.btn_main_contact:
            changeFragment(contactFragment);
            break;
        }
    }
};

@Override
public void onClick(ContactObject contact) {
    // TODO Auto-generated method stub
    displayContact(contact);
}
}

当我点击Contact时，我选择了一个联系人，再次点击Contact，然后我开始点击我的back按钮，抛出一个“IllegalStateException；Fragment ready added:ContactFragment”。我不明白为什么

下面是日志：

    07-02 13:32:31.046: E/AndroidRuntime(11412): FATAL EXCEPTION: main
07-02 13:32:31.046: E/AndroidRuntime(11412): java.lang.IllegalStateException: Fragment already added: ContactFragment{420b6a40 #0 id=0x7f060000}
07-02 13:32:31.046: E/AndroidRuntime(11412):    at 安卓.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1192)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at 安卓.support.v4.app.BackStackRecord.run(BackStackRecord.java:646)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at 安卓.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1484)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at 安卓.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:482)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at com.big5media.ercoiffure.MainActivity.changeFragment(MainActivity.java:57)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at com.big5media.ercoiffure.MainActivity.access$1(MainActivity.java:55)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at com.big5media.ercoiffure.MainActivity$1.onClick(MainActivity.java:79)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at 安卓.view.View.performClick(View.java:4240)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at 安卓.view.View$PerformClick.run(View.java:17721)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at 安卓.os.Handler.handleCallback(Handler.java:730)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at 安卓.os.Handler.dispatchMessage(Handler.java:92)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at 安卓.os.Looper.loop(Looper.java:137)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at 安卓.app.ActivityThread.main(ActivityThread.java:5103)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at java.lang.reflect.Method.invokeNative(Native Method)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at java.lang.reflect.Method.invoke(Method.java:525)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at com.安卓.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at com.安卓.internal.os.ZygoteInit.main(ZygoteInit.java:553)
07-02 13:32:31.046: E/AndroidRuntime(11412):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

在changeFragment方法中，如果不需要导航回，请尝试使用addToBackStack（null）追加。。。否则，最好删除片段并再次添加

manager.beginTransaction().replace(R.id.fl_main_container, f).addToBackStack(null).commit();