底部导航栏（1）

src/main/java/com/hnucm/c202201020328/CommunityActivity.java

@@ -7,12 +7,18 @@ import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.graphics.Insets;
 import androidx.core.view.ViewCompat;
 import androidx.core.view.WindowInsetsCompat;
+import androidx.fragment.app.Fragment;
 
 public class CommunityActivity extends AppCompatActivity {
-
+    SquareFragment squareFragment=new SquareFragment();
+    MessageFragment messageFragment=new MessageFragment();
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_community);
+        //布局切换成fragment
+        getSupportFragmentManager().beginTransaction().add(R.id.layout,squareFragment).commit();
+        getSupportFragmentManager().beginTransaction().add(R.id.layout,messageFragment).commit();
+        getSupportFragmentManager().beginTransaction().hide(messageFragment).show(squareFragment).commit();
     }
 }

src/main/java/com/hnucm/c202201020328/MessageFragment.java

@@ -0,0 +1,64 @@
+package com.hnucm.c202201020328;
+
+import android.os.Bundle;
+
+import androidx.fragment.app.Fragment;
+
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+/**
+ * A simple {@link Fragment} subclass.
+ * Use the {@link MessageFragment#newInstance} factory method to
+ * create an instance of this fragment.
+ */
+public class MessageFragment 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;
+
+    public MessageFragment() {
+        // 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 MessageFragment.
+     */
+    // TODO: Rename and change types and number of parameters
+    public static MessageFragment newInstance(String param1, String param2) {
+        MessageFragment fragment = new MessageFragment();
+        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
+        return inflater.inflate(R.layout.fragment_message, container, false);
+    }
+}

src/main/java/com/hnucm/c202201020328/SquareFragment.java

@@ -0,0 +1,65 @@
+package com.hnucm.c202201020328;
+
+import android.os.Bundle;
+
+import androidx.fragment.app.Fragment;
+
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+/**
+ * A simple {@link Fragment} subclass.
+ * Use the {@link SquareFragment#newInstance} factory method to
+ * create an instance of this fragment.
+ */
+public class SquareFragment 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;
+
+    public SquareFragment() {
+        // 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 SquareFragment.
+     */
+    // TODO: Rename and change types and number of parameters
+    public static SquareFragment newInstance(String param1, String param2) {
+        SquareFragment fragment = new SquareFragment();
+        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_square, container, false);
+        return view;
+    }
+}

src/main/res/layout/activity_community.xml

@@ -5,6 +5,64 @@
     android:id="@+id/main"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:background="#FFFFFF"
     tools:context=".CommunityActivity">
 
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:id="@+id/layout"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:layout_marginBottom="57dp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.0"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintVertical_bias="0.0"/>
+
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:layout_width="match_parent"
+        android:layout_height="57dp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.0"
+        app:layout_constraintStart_toStartOf="parent">
+
+        <androidx.constraintlayout.widget.ConstraintLayout
+            android:id="@+id/constraintLayout3"
+            android:layout_width="0dp"
+            android:layout_height="match_parent"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/constraintLayout2"
+            app:layout_constraintHorizontal_bias="0.5"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent">
+
+        </androidx.constraintlayout.widget.ConstraintLayout>
+
+        <androidx.constraintlayout.widget.ConstraintLayout
+            android:id="@+id/constraintLayout2"
+            android:layout_width="0dp"
+            android:layout_height="match_parent"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/constraintLayout4"
+            app:layout_constraintHorizontal_bias="0.5"
+            app:layout_constraintStart_toEndOf="@+id/constraintLayout3"
+            app:layout_constraintTop_toTopOf="parent">
+
+        </androidx.constraintlayout.widget.ConstraintLayout>
+
+        <androidx.constraintlayout.widget.ConstraintLayout
+            android:id="@+id/constraintLayout4"
+            android:layout_width="0dp"
+            android:layout_height="match_parent"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintHorizontal_bias="0.5"
+            app:layout_constraintStart_toEndOf="@+id/constraintLayout2"
+            app:layout_constraintTop_toTopOf="parent">
+
+        </androidx.constraintlayout.widget.ConstraintLayout>
+    </androidx.constraintlayout.widget.ConstraintLayout>
+
 </androidx.constraintlayout.widget.ConstraintLayout>

src/main/res/layout/fragment_message.xml

@@ -0,0 +1,19 @@
+<?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=".MessageFragment">
+
+    <!-- TODO: Update blank fragment layout -->
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:text="@string/hello_blank_fragment"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

src/main/res/layout/fragment_square.xml

@@ -0,0 +1,21 @@
+<?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="#f23"
+    tools:context=".SquareFragment">
+
+    <!-- TODO: Update blank fragment layout -->
+    <TextView
+        android:id="@+id/textview"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:text="@string/hello_blank_fragment"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

src/main/res/values/strings.xml

@@ -1,3 +1,5 @@
 <resources>
     <string name="app_name">My Project</string>
+    <!-- TODO: Remove or change this placeholder text -->
+    <string name="hello_blank_fragment">Hello blank fragment</string>
 </resources>