Add previous page

app/src/main/AndroidManifest.xml

@@ -12,6 +12,9 @@
         android:supportsRtl="true"
         android:theme="@style/Theme.Android101"
         tools:targetApi="31">
+        <activity
+            android:name=".Page3"
+            android:exported="false" />
         <activity
             android:name=".MainActivity2"
             android:exported="false" />
@@ -19,8 +22,9 @@
             android:name=".MainActivity"
             android:exported="true">
             <intent-filter>
-                <action android:name="android.intent.action.MAIN"/>
-                <category android:name="android.intent.category.LAUNCHER"/>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
     </application>

app/src/main/java/uk/kagurach/android101/MainActivity2.java

@@ -1,10 +1,12 @@
 package uk.kagurach.android101;
 
+import android.content.Intent;
 import android.graphics.Color;
 import android.os.Bundle;
 import android.util.Log;
 import android.util.TypedValue;
 import android.view.View;
+import android.widget.Button;
 import android.widget.EditText;
 import android.widget.TextView;
 
@@ -29,6 +31,14 @@ public class MainActivity2 extends AppCompatActivity {
         Log.d("K","2");
     }
 
+    @Override
+    protected void onResume(){
+        super.onResume();
+        Button button = findViewById(R.id.next_page_nav_2);
+        button.setOnClickListener(new PageButtonHandler());
+        button.setOnLongClickListener(new LongClickHandler());
+    }
+
 
     public void set70sp(View view) {
         TextView t = findViewById(R.id.test2strview);
@@ -67,4 +77,31 @@ public class MainActivity2 extends AppCompatActivity {
         }
 
     }
-}
+    public void goNext() {
+        Intent myIntent = new Intent(this, Page3.class);
+        startActivity(myIntent);
+    };
+
+    public void goPrev() {
+        Intent myIntent = new Intent(this, MainActivity.class);
+        startActivity(myIntent);
+    };
+
+    final class PageButtonHandler implements View.OnClickListener
+    {
+        @Override
+        public void onClick(View v){
+            goNext();
+        }
+    }
+
+    final class LongClickHandler implements View.OnLongClickListener
+    {
+        @Override
+        public boolean onLongClick(View v){
+            goPrev();
+            return false;
+        }
+    }
+}
+

app/src/main/java/uk/kagurach/android101/Page3.java

@@ -0,0 +1,24 @@
+package uk.kagurach.android101;
+
+import android.os.Bundle;
+
+import androidx.activity.EdgeToEdge;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.core.graphics.Insets;
+import androidx.core.view.ViewCompat;
+import androidx.core.view.WindowInsetsCompat;
+
+public class Page3 extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        EdgeToEdge.enable(this);
+        setContentView(R.layout.activity_page3);
+        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
+            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
+            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
+            return insets;
+        });
+    }
+}

app/src/main/res/layout/activity_main2.xml

@@ -101,11 +101,12 @@
                 android:onClick="setColor"/>
 
             <Button
-                android:id="@+id/button7"
+                android:id="@+id/next_page_nav_2"
                 android:layout_width="wrap_content"
                 android:layout_height="match_parent"
                 android:layout_weight="1"
-                android:text="@string/next_page" />
+                android:text="@string/two_way_page"
+                />
         </LinearLayout>
 
 

app/src/main/res/layout/activity_page3.xml

@@ -0,0 +1,10 @@
+<?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:id="@+id/main"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".Page3">
+
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/values/strings.xml

@@ -2,6 +2,7 @@
     <string name="app_name">Android101</string>
     <string name="hello_world">你好,世界!</string>
     <string name="next_page">下一页</string>
+    <string name="two_way_page">单击下一页，长桉上一页</string>
     <string name="test_str">测试文本</string>
     <string name="set_color">设置颜色</string>
 </resources>