我是Android新手，对我丑陋的英语感到抱歉
我有两个片段，主要任务是：
ProfileFragment.java
private void initUI(View parent) {
/**
* referencing of fragment_profile
*/
fragmentImageProfile = (CircleImageView) parent.findViewById(R.id.fragment_profile_picture);
fragmentName = (EditText) parent.findViewById(R.id.fragment_profile_editText_name);
fragmentFamily = (EditText) parent.findViewById(R.id.fragment_profile_editText_family);
fragmentPhoneNumber = (EditText) parent.findViewById(R.id.fragment_profile_editText_phone);
/**
* get contact by invoke from CallBack on ProfileActivity
*/
Contact contact = profileCallBack.getContact();
fragmentName.setText(contact.getName());
fragmentFamily.setText(contact.getFamily());
fragmentPhoneNumber.setText(contact.getPhonNumber());
Log.i("==>", "initUI: "+ contact.getName());
}
及其Lauout
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Name: "
android:textSize="20dp" />
<EditText
android:id="@+id/fragment_profile_editText_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:cursorVisible="true"
android:enabled="false"
android:focusable="false" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Family: "
android:textSize="20dp" />
<EditText
android:id="@+id/fragment_profile_editText_family"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:enabled="false"
android:focusable="false"
android:inputType="none" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Phone: "
android:textSize="20dp" />
<EditText
android:id="@+id/fragment_profile_editText_phone"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:enabled="false"
android:focusable="false"
android:inputType="none" />
</LinearLayout>
在这个片段中，我将联系人的字段设置为3个编辑文本。 EditProfileFragment.java
public void updateContact() {
int id = contact.get_id();
String name = fragmentEditEditTextName.getText().toString();
Log.i("==>", "Name Update: " + name);
String family = fragmentEditEditTextFamily.getText().toString();
String phoneNumber = fragmentEditEditTextPhoneNumber.getText().toString();
int rowUpdate = App.getInstanceImplementation().updateContact(
new Contact(id, name, family, phoneNumber, "image"));
Log.i("==>", "btnUpdateContact: " + rowUpdate);
}
和这个布局
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Name: "
android:textSize="20dp" />
<EditText
android:id="@+id/fragment_edit_editText_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:cursorVisible="true"
android:inputType="text"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Family: "
android:textSize="20dp" />
<EditText
android:id="@+id/fragment_edit_editText_family"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="text" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Phone: "
android:textSize="20dp" />
<EditText
android:id="@+id/fragment_edit_editText_phone"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="phone" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button
android:id="@+id/fragment_edit_btn_save"
style="@style/Widget.AppCompat.Button.Borderless.Colored"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="24dp"
android:layout_marginRight="2dp"
android:onClick="btnUpdateContact"
android:layout_weight="1"
android:background="#8d860000"
android:padding="12dp"
android:text="Update" />
<Button
android:id="@+id/fragment_edit_btn_exit"
style="@style/Widget.AppCompat.Button.Borderless.Colored"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="24dp"
android:onClick="btnExitContact"
android:layout_weight="1"
android:background="#8d860000"
android:padding="12dp"
android:text="Exit" />
</LinearLayout>
我更新了数据库。 在我的ProfileActivity中，我使用ViewPager通过CallBack Listener显示这些片段和这些片段与活动的连接。
public class ProfileActivity extends FragmentActivity implements ProfileFragment.ProfileCallBack , EditProfileFragment.EditFragmentCallBack {
private ProfileFragment profileFragment;
private EditProfileFragment editProfileFragment;
private PagerAdapterFragment adapterFragment;
private List<Fragment> fragments;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_profile);
}
@Override
protected void onResume() {
super.onResume();
getProfileFragment();
getEditProfileFragment();
initFragment();
}
private void initFragment() {
fragments = new Vector<>();
fragments.add(Fragment.instantiate(this, ProfileFragment.class.getName()));
fragments.add(Fragment.instantiate(this, EditProfileFragment.class.getName()));
adapterFragment = new PagerAdapterFragment(this.getSupportFragmentManager(), fragments);
ViewPager pager = (ViewPager) findViewById(R.id.vpg_main_content);
pager.setAdapter(adapterFragment);
}
private ProfileFragment getProfileFragment() {
if (profileFragment == null) {
profileFragment = new ProfileFragment();
}
Log.i("==>", "getProfileFragment:" + profileFragment.getId());
return profileFragment;
}
private EditProfileFragment getEditProfileFragment() {
if (editProfileFragment == null) {
editProfileFragment = new EditProfileFragment();
}
Log.i(">", "getEditProfileFragment: "+ editProfileFragment.getId());
return editProfileFragment;
}
@Override
public Contact getContact() {
Intent intent = getIntent();
return (Contact) intent.getSerializableExtra(Contact.class.getName());
}
@Override
public void finishProfile() {
// TODO: 2/3/2017
// finish();
}
public void btnUpdateContact(View view) {
getEditProfileFragment().updateContact();
}
public void btnExitContact(View view) {
// getEditProfileFragment().btnExitContact();
finish();
}
但在此行public void btnUpdateContact(View view)中出现此错误：
02-04 01:23:40.953 4545-4545/com.example.sayres.myapplication7 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.sayres.myapplication7, PID: 4545
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:3823)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3818)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.sayres.myapplication7.mvp.view.profile.EditProfileFragment.updateContact(EditProfileFragment.java:70)
at com.example.sayres.myapplication7.mvp.view.profile.ProfileActivity.btnUpdateContact(ProfileActivity.java:97)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3818)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
问题在于：
private ProfileFragment getProfileFragment() {
if (profileFragment == null) {
profileFragment = new ProfileFragment(); //you need to change this as this will only create an object and doesn't initialize any view;
}
Log.i("==>", "getProfileFragment:" + profileFragment.getId());
return profileFragment;
}
现在，如果您对从上面的方法收到的对象调用 updateCon tact（）方法，则在您尝试访问fragmentEditEditTextName文本视图时会抛出异常。
更改getProfileFragment（）中的以下行：
profileFragment = new ProfileFragment();
到：
profileFragment = fragments.get(1);