英文:
Navigation doesnt proceed to next fragment on click
问题
在按钮点击时，奇怪的是它不转到其他片段。
activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
android:minHeight="?attr/actionBarSize"
android:theme="?attr/actionBarTheme"
app:logo="@android:drawable/btn_star_big_on" />
<fragment
android:id="@+id/fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="@navigation/main_nav" />
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
fragment_first.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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"
android:background="@color/colorPrimary"
android:elevation="20dp"
tools:context=".first">
<Button
android:id="@+id/button_first"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:elevation="20dp"
android:text="First"
android:textColor="@color/colorPrimary"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
fragment_second.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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"
android:background="#C13584"
tools:context=".second">
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Second"
android:textColor="#C13584"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
main_nav.xml：
<?xml version="1.0" encoding="utf-8"?>
<navigation 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:id="@+id/main_nav"
app:startDestination="@id/first">
<fragment
android:id="@+id/first"
android:name="com.example.fragments.first"
android:label="fragment_first"
tools:layout="@layout/fragment_first">
<action
android:id="@+id/navigateToSecondFragment"
app:destination="@id/second" />
</fragment>
<fragment
android:id="@+id/second"
android:name="com.example.fragments.second"
android:label="fragment_second"
tools:layout="@layout/fragment_second">
<action
android:id="@+id/navigateToFirstFragment"
app:destination="@id/first" />
</fragment>
</navigation>
first.java：
package com.example.fragments;
import android.os.Bundle;
import androidx.fragment.app.Fragment;
import androidx.navigation.Navigation;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
public class first extends Fragment {
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
private String mParam1;
private String mParam2;
private Button button;
public first() {
// Required empty public constructor
}
public static first newInstance(String param1, String param2) {
first fragment = new first();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_first, container, false);
button = (Button) view.findViewById(R.id.button_first);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Navigation.findNavController(view).navigate(R.id.navigateToSecondFragment);
}
});
return view;
}
}
second.java：
package com.example.fragments;
import android.os.Bundle;
import androidx.fragment.app.Fragment;
import androidx.navigation.Navigation;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
public class second extends Fragment {
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
private String mParam1;
private String mParam2;
private Button button;
public second() {
// Required empty public constructor
}
public static second newInstance(String param1, String param2) {
second fragment = new second();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM
<details>
<summary>英文:</summary>
As the title describes on button click it doesnt go to the other fragment for some odd reason.
activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
android:minHeight="?attr/actionBarSize"
android:theme="?attr/actionBarTheme"
app:logo="@android:drawable/btn_star_big_on" />
<fragment
android:id="@+id/fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="@navigation/main_nav" />
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
fragment_first.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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"
android:background="@color/colorPrimary"
android:elevation="20dp"
tools:context=".first">
<Button
android:id="@+id/button_first"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:elevation="20dp"
android:text="First"
android:textColor="@color/colorPrimary"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
fragment_second.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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"
android:background="#C13584"
tools:context=".second">
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Second"
android:textColor="#C13584"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
main_nav.xml:
<?xml version="1.0" encoding="utf-8"?>
<navigation 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:id="@+id/main_nav"
app:startDestination="@id/first">
<fragment
android:id="@+id/first"
android:name="com.example.fragments.first"
android:label="fragment_first"
tools:layout="@layout/fragment_first" >
<action
android:id="@+id/navigateToSecondFragment"
app:destination="@id/second" />
</fragment>
<fragment
android:id="@+id/second"
android:name="com.example.fragments.second"
android:label="fragment_second"
tools:layout="@layout/fragment_second" >
<action
android:id="@+id/navigateToFirstFragment"
app:destination="@id/first" />
</fragment>
</navigation>
first.java:
package com.example.fragments;
import android.os.Bundle;
import androidx.fragment.app.Fragment;
import androidx.navigation.Navigation;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
/**
* A simple {@link Fragment} subclass.
* Use the {@link first#newInstance} factory method to
* create an instance of this fragment.
*/
public class first extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private Button button;
public first() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment first.
*/
// TODO: Rename and change types and number of parameters
public static first newInstance(String param1, String param2) {
first fragment = new first();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_first, container, false);
button = (Button) view.findViewById(R.id.button_first);
button.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view) {
//Start second view
//Navigation.findNavController(view).navigate(R.id.);
Navigation.findNavController(view).navigate(R.id.navigateToSecondFragment);
}
});
return view;
}
}
second.java:
package com.example.fragments;
import android.os.Bundle;
import androidx.fragment.app.Fragment;
import androidx.navigation.Navigation;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
/**
* A simple {@link Fragment} subclass.
* Use the {@link second#newInstance} factory method to
* create an instance of this fragment.
*/
public class second extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private Button button;
public second() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment second.
*/
// TODO: Rename and change types and number of parameters
public static second newInstance(String param1, String param2) {
second fragment = new second();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_first, container, false);
button = (Button) view.findViewById(R.id.button_first);
button.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view) {
//Start first view
Navigation.findNavController(view).navigate(R.id.navigateToFirstFragment);
}
});
return view;
}
}
</details>
# 答案1
**得分**: 1
对于您的“第二个”片段，您正在填充用于“第一个”片段的布局，即`R.layout.fragment_first`。您的导航可能实际上运行良好（我没有发现任何问题），只是两个片段的布局相同，因此您不会注意到转换，因为没有定义转换动画。检查当您点击按钮时是否导航栏的标题会更改（从“fragment_first”到“fragment_second”，如标签中所定义的那样），如果是，则问题不在于导航。
<details>
<summary>英文:</summary>
For your `second` fragment, you are inflating layout that is meant to be for the `first` fragment, i.e. `R.layout.fragment_first`. Your navigation may actually be working fine (I did not find any issue), it is just that the layout for both fragments are the same, so you would not notice the transition, as no transition animations were defined. Check if the navigationBar's title changes when you click the button (from `fragment_first` to `fragment_second`, as defined by the labels), if yes, then the issue is not in navigation.
</details>
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