我试图将“名字”从registerFragmentOne传递到registerFragmentTwo。但是每次我启动应用程序时，它突然关闭。我从Logcat收到此错误：
在com.application.name.registerFragmentTwo.onCreateView
这是：
String frag1 = bundle.getString("firstname");
我在两个片段上都声明了捆绑。
registerFragmentOne：
package com.sholomon.who.who;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class registerFragmentOne extends Fragment {
private Button fButton;
private EditText fName;
private TextView fTextView;
private Animation shake;
private boolean flagAnimate = false;
private final Animation in = new AlphaAnimation(0.0f , 1.0f);
private final Animation out = new AlphaAnimation(1.0f, 0.0f);
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_register_fragment_one, container, false);
fButton = (Button) view.findViewById(R.id.fButton);
fName = (EditText) view.findViewById(R.id.fName);
fTextView = (TextView) view.findViewById(R.id.fTextView);
// Animation List
shake = AnimationUtils.loadAnimation(getActivity(), R.anim.shake);
in.setDuration(500);
out.setDuration(500);
fName.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
String getName = fName.getText().toString();
int getNameCount = getName.replaceAll("\\s+","").length();
if(getNameCount >= 1 && !flagAnimate) {
fTextView.startAnimation(in);
fTextView.setVisibility(View.VISIBLE);
flagAnimate= true;
} else if(getNameCount == 0){
fTextView.startAnimation(out);
fTextView.setVisibility(View.INVISIBLE);
flagAnimate= false;
}
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void afterTextChanged (Editable s){
// TODO Auto-generated method stub
}
});
fButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(fName.length() < 1) {
fName.startAnimation(shake);
} else {
String firstName = fName.getText().toString();
Bundle bundle = new Bundle();
bundle.putString("firstname", firstName);
registerFragmentTwo fragobj = new registerFragmentTwo();
fragobj.setArguments(bundle);
Toast.makeText(getActivity(), bundle.getString("firstname"), Toast.LENGTH_LONG).show();
((RegisterActivity)getActivity()).setViewPager(1);
}
}
});
return view;
}
}
registerFragmentTwo：
package com.sholomon.who.who;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import org.w3c.dom.Text;
public class registerFragmentTwo extends Fragment {
private Button mButton;
private EditText mName;
private TextView mTextView, nameViewOne;
private String frag1;
private Animation shake;
private boolean flagAnimate = false;
private final Animation in = new AlphaAnimation(0.0f , 1.0f);
private final Animation out = new AlphaAnimation(1.0f, 0.0f);
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_register_fragment_two, container, false);
mButton = (Button) view.findViewById(R.id.mButton);
mName = (EditText) view.findViewById(R.id.mName);
mTextView = (TextView) view.findViewById(R.id.mTextView);
// Animation List
shake = AnimationUtils.loadAnimation(getActivity(), R.anim.shake);
in.setDuration(500);
out.setDuration(500);
Bundle bundle = getArguments();
nameViewOne = (TextView) view.findViewById(R.id.nameViewOne);
String frag1 = bundle.getString("firstname");
nameViewOne.setText(frag1 + " ...");
mName.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
String getName = mName.getText().toString();
int getNameCount = getName.replaceAll("\\s+","").length();
if(getNameCount >= 1 && !flagAnimate) {
mTextView.startAnimation(in);
mTextView.setVisibility(View.VISIBLE);
flagAnimate= true;
} else if(getNameCount == 0){
mTextView.startAnimation(out);
mTextView.setVisibility(View.INVISIBLE);
flagAnimate= false;
}
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void afterTextChanged (Editable s){
// TODO Auto-generated method stub
}
});
mButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(mName.length() < 1) {
mName.startAnimation(shake);
} else {
//GlobalClass.firstName = mName.getText().toString();
((RegisterActivity) getActivity()).setViewPager(0);
}
}
});
return view;
}
}
registerFragmentTwo XML：
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.sholomon.who.who.registerFragmentTwo">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/nameViewOne"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/mTextView"
android:layout_alignStart="@+id/mTextView"
android:layout_marginBottom="53dp"
android:textSize="25dp"
android:text="TextView" />
<TextView
android:id="@+id/mTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/mName"
android:layout_alignStart="@+id/mName"
android:text="First Name"
android:visibility="invisible" />
<EditText
android:id="@+id/mName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_above="@+id/mButton"
android:layout_centerHorizontal="true"
android:layout_marginBottom="126dp"
android:layout_marginLeft="15dp"
android:layout_marginRight="15dp"
android:background="@drawable/edittext"
android:ems="10"
android:hint="Middle Name"
android:inputType="textCapSentences"
android:paddingBottom="15dp"
android:paddingTop="15dp"
android:textSize="20dp" />
<Button
android:id="@+id/mButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="12dp"
android:layout_marginLeft="15dp"
android:layout_marginRight="15dp"
android:background="@drawable/button_register" />
</RelativeLayout>
</android.support.constraint.ConstraintLayout>
RegisterActivity ：（在我加载片段的位置）
public class RegisterActivity extends AppCompatActivity {
private FirebaseAuth mAuth;
private FirebaseUser firebaseUser;
private DatabaseReference mDatabase;
private SectionsStatePagerAdapter sectionsStatePagerAdapter;
private ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getSupportActionBar().hide();
AppCompatDelegate.setCompatVectorFromResourcesEnabled(true);
setContentView(R.layout.activity_register);
mAuth = FirebaseAuth.getInstance();
firebaseUser = mAuth.getCurrentUser();
mDatabase = FirebaseDatabase.getInstance().getReference();
mViewPager = (ViewPager) findViewById(R.id.mainContainer);
// Setup Adapter
setupViewPager(mViewPager);
}
private void setupViewPager(ViewPager viewPager) {
SectionsStatePagerAdapter adapter = new SectionsStatePagerAdapter(getSupportFragmentManager());
adapter.addFragment(new registerFragmentOne(), "First Name");
adapter.addFragment(new registerFragmentTwo(), "Second Name");
viewPager.setAdapter(adapter);
}
// Will be accessed from outside in order to navigate on the next item
public void setViewPager(int fragmentNumber) {
mViewPager.setCurrentItem(fragmentNumber);
}
}
我做对了吗？我不知道为什么加载第二个Fragment后Bundle的值消失了。我尝试在加载第二个片段之前敬酒它，在加载下一个片段之前它具有价值。
编辑：整个logcat错误
FATAL EXCEPTION: main
Process: com.application.name, PID: 8683
java.lang.NullPointerException
at com.sholomon.application.name.onCreateView(registerFragmentTwo.java:50)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:2354)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1419)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1740)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1809)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:799)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2580)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2367)
at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2322)
at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:2199)
at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:651)
at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:167)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1236)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1084)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1614)
at android.view.View.measure(View.java:16834)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:824)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:500)
at android.view.View.measure(View.java:16834)
at android.support.constraint.ConstraintLayout.internalMeasureChildren(ConstraintLayout.java:934)
at android.support.constraint.ConstraintLayout.onMeasure(ConstraintLayout.java:973)
at android.view.View.measure(View.java:16834)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5374)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:340)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
at android.view.View.measure(View.java:16834)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5374)
at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:400)
at android.view.View.measure(View.java:16834)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5374)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:340)
at android.view.View.measure(View.java:16834)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5374)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1621)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:742)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:607)
at android.view.View.measure(View.java:16834)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5374)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:340)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2333)
at android.view.View.measure(View.java:16834)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2246)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1312)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1509)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1189)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6223)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:788)
at android.view.Choreographer.doCallbacks(Choreographer.java:591)
at android.view.Choreographer.doFrame(Choreographer.java:560)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:774)
at android.os.Handler.handleCallback(Handler.java:808)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5292)
at java.lang.reflect.Method.invokeNative(Native Meth
最佳答案
ViewPager创建并缓存其某些片段，然后将其显示。在这种情况下，将在用户开始输入第一个片段之前创建第二个片段。这意味着onCreateView()在创建参数束之前执行。
要解决此问题，请将bundle.getString()的代码放入其他生命周期回调中，例如onResume()。