activity与fragment以及fragment与fragment之间的通信
demo下载地址:https://download.csdn.net/download/rely_on_yourself/10711450
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activity向其引用的fragment传值
第一步 : Activity中创建Fragment对象 , 调用setArguments(bundle) 方法存储值
第二步 : Fragment中调用getArguments()获取传递的Bundle对象 , 解析获取具体值
具体代码:
Activity Code
public class OneActivity extends AppCompatActivity {
private FragmentTransaction mFragmentTransaction;
private FragmentManager mManager;
private EditText mEt;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_one);
mEt = findViewById(R.id.et);
OneFragment oneFragment = new OneFragment();
mManager = getFragmentManager();
mFragmentTransaction = mManager.beginTransaction();
mFragmentTransaction.add(R.id.ll,oneFragment);
mFragmentTransaction.commit();
}
public void sendValue(View view) {
//创建Bundle对象 , 将需要传递的数据存储到bundle中 , 然后调用fragment的setArguments()方法传递bundle
String value = mEt.getText().toString().trim();
OneFragment oneFragment = new OneFragment();
Bundle bundle = new Bundle();
bundle.putString("lyx",value);
oneFragment.setArguments(bundle);
mManager = getFragmentManager();
mFragmentTransaction = mManager.beginTransaction();
mFragmentTransaction.replace(R.id.ll,oneFragment);
mFragmentTransaction.commit();
}
}
Fragment Code(注意:此处使用的Fragment是app包下的)
public class OneFragment extends Fragment {
private TextView mTv;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
@Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_one, null);
mTv = view.findViewById(R.id.tv);
//先调用getArguments()方法获取bundle , bundle对象中根据key值获取传递的数据 , 展示在TextView中
Bundle bundle = getArguments();
if (bundle != null) {
String value = bundle.getString("lyx");
mTv.setText(value);
}
return view;
}
}
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fragment向其所属的activity传值
第一步 : Fragment中定义传值的回调接口 , 在声明周期的onAttach()或onCreate()方法中获取接口的实现 .
第二步 : Fragment需要传值的位置调用接口回调方法传值 .
第三步 : Activity实现回调接口重写回调方法获取传递的值 .
具体代码:
Activity Code
public class TwoActivity extends AppCompatActivity implements TwoFragment.MyListener {
private TextView mTv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_two);
mTv = findViewById(R.id.tv);
}
@Override
public void sendMessage(String str) {
//回传数据进行展示
if (!TextUtils.isEmpty(str)) {
mTv.setText(str);
}
}
}
Fragment Code
public class TwoFragment extends Fragment {
private EditText mEt;
private Button mBtn;
private MyListener mListener;
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
mListener = (MyListener) activity;
}
// @Override
// public void onCreate(@Nullable Bundle savedInstanceState) {
// super.onCreate(savedInstanceState);
// //此处创建Listener具体的对象
// //Listener是一个接口 接口是不能直接实例化为具体对象的 这个时候创建对象时 都是创建接口的子类
// //现在TwoActivity是Listener接口的子类 因为TwoActivity实现了MyListener接口
// mListener = (MyListener) getActivity();
// }
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_two, null);
mEt = view.findViewById(R.id.et);
mBtn = view.findViewById(R.id.btn);
mBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String value = mEt.getText().toString().trim();
//接口回调的形式回传数据
//java多态 父类的引用指向子类的对象
mListener.sendMessage(value);
}
});
return view;
}
@Override
public void onDetach() {
super.onDetach();
//调用onDetach()方法 , 这个时候要把传递进来的activity对象释放掉
mListener = null;
}
public interface MyListener {
void sendMessage(String str);
}
}
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属于同一个activity的多个或两个fragment之间的传值
实际开发中 , 同一个Activity中会引用多个Fragment , 多个Fragment之间也会涉及到一个传值的过程 . 实际上Fragment之间传值 , 可以通过上面介绍的两种方式结合起来传值 , fragment先传值给activity , 然后activty再传值给另外一个fragment . 出了这种方式之外 , 还有几种其他方式传值 .
1.调用getFragmentManager().findFragmentById()获取Fragment对象调用方法;
2.getFragmentManager().findFragmentById().getView().findViewById()根据id获取activty中的fragment对象获取fragment视图 , 根据id获取视图中控件对象;
3.getActivity().findViewById()获取当前所属Activity根据id获取View对象.
具体代码:
ThreeLeftFragment Code
public class ThreeLeftFragment extends Fragment {
private EditText mEt;
private Button mBtn;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_three_left, null);
mEt = view.findViewById(R.id.et);
mBtn = view.findViewById(R.id.btn);
mBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String value = mEt.getText().toString().trim();
//方式一:可以调用findFragmentById()方法根据id获得fragment的对象 , 调用fragment中的方法赋值
ThreeRightFragment fragment = (ThreeRightFragment) getFragmentManager().findFragmentById(R.id.right);
fragment.setTextView(value);
//方式二:先调用getFragmentManager()获取fragmentManager对象 , 然后调用findFragmentById()方法获得右侧fragment
//再调用getView()获得右侧fragment的view对象 , 最后调用view的findViewById获得赋值的控件
// ThreeRightFragment fragment = (ThreeRightFragment) getFragmentManager().findFragmentById(R.id.right);
// TextView tv = fragment.getView().findViewById(R.id.tv);
// tv.setText(value);
//方式三:先调用getActivity()方法获取所属的activity的对象 , 然后调用findViewById()获取目标控件
// TextView tv = getActivity().findViewById(R.id.tv);
// tv.setText(value);
}
});
return view;
}
}
ThreeRightFragment Code
public class ThreeRightFragment extends Fragment {
private TextView mTv;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_three_right, null);
mTv = view.findViewById(R.id.tv);
return view;
}
public void setTextView(String string) {
mTv.setText(string);
}
}