使用片段传递数据的完整代码

Fragment fragment = new Fragment(); // replace your custom fragment class 
Bundle bundle = new Bundle();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
                bundle.putString("key","value"); // use as per your need
                fragment.setArguments(bundle);
                fragmentTransaction.addToBackStack(null);
                fragmentTransaction.replace(viewID,fragment);
                fragmentTransaction.commit();

在自定义片段类中

Bundle mBundle = new Bundle();
mBundle = getArguments();
mBundle.getString(key);  // key must be same which was given in first fragment

使用Bundle。这里有一个例子:

Fragment fragment = new Fragment();
Bundle bundle = new Bundle();
bundle.putInt(key, value);
fragment.setArguments(bundle);

Bundle为许多数据类型提供了方法。看到这个

然后在你的片段，检索数据(例如在onCreate()方法):

Bundle bundle = this.getArguments();
if (bundle != null) {
        int myInt = bundle.getInt(key, defaultValue);
}

使用片段传递数据的完整代码

Fragment fragment = new Fragment(); // replace your custom fragment class 
Bundle bundle = new Bundle();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
                bundle.putString("key","value"); // use as per your need
                fragment.setArguments(bundle);
                fragmentTransaction.addToBackStack(null);
                fragmentTransaction.replace(viewID,fragment);
                fragmentTransaction.commit();

在自定义片段类中

Bundle mBundle = new Bundle();
mBundle = getArguments();
mBundle.getString(key);  // key must be same which was given in first fragment

如果你使用图表在片段之间导航，你可以这样做:

    Bundle bundle = new Bundle();
    bundle.putSerializable(KEY, yourObject);
    Navigation.findNavController(view).navigate(R.id.fragment, bundle);

片段B:

    Bundle bundle = getArguments();
    object = (Object) bundle.getSerializable(KEY);

当然你的对象必须实现Serializable

getArguments()返回null因为“它没有得到任何东西”

试试这段代码来处理这种情况

if(getArguments()!=null)
{
int myInt = getArguments().getInt(key, defaultValue);
}

            First Fragment Sending String To Next Fragment
            public class MainActivity extends AppCompatActivity {
                    private Button Add;
                    private EditText edt;
                    FragmentManager fragmentManager;
                    FragClass1 fragClass1;


                    @Override
                    protected void onCreate(Bundle savedInstanceState) {
                        super.onCreate(savedInstanceState);
                        setContentView(R.layout.activity_main);
                        Add= (Button) findViewById(R.id.BtnNext);
                        edt= (EditText) findViewById(R.id.editText);

                        Add.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View v) {
                                fragClass1=new FragClass1();
                                Bundle bundle=new Bundle();

                                fragmentManager=getSupportFragmentManager();
                                fragClass1.setArguments(bundle);
                                bundle.putString("hello",edt.getText().toString());
                                FragmentTransaction fragmentTransaction=fragmentManager.beginTransaction();
                                fragmentTransaction.add(R.id.activity_main,fragClass1,"");
                                fragmentTransaction.addToBackStack(null);
                                fragmentTransaction.commit();

                            }
                        });
                    }
                }
         Next Fragment to fetch the string.
            public class FragClass1 extends Fragment {
                  EditText showFrag1;


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

                        View view=inflater.inflate(R.layout.lay_frag1,null);
                        showFrag1= (EditText) view.findViewById(R.id.edtText);
                        Bundle bundle=getArguments();
                        String a=getArguments().getString("hello");//Use This or The Below Commented Code
                        showFrag1.setText(a);
                        //showFrag1.setText(String.valueOf(bundle.getString("hello")));
                        return view;
                    }
                }
    I used Frame Layout easy to use.
    Don't Forget to Add Background color or else fragment will overlap.
This is for First Fragment.
    <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/activity_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        android:background="@color/colorPrimary"
        tools:context="com.example.sumedh.fragmentpractice1.MainActivity">

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/editText" />
        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:id="@+id/BtnNext"/>
    </FrameLayout>


Xml for Next Fragment.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
   android:background="@color/colorAccent"
    android:layout_height="match_parent">
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/edtText"/>

</LinearLayout>