fragment实现tab功能

fragment实现tab功能，可理解为iframe

fragment代码，menu1.java - men4.java,指向不同的layout xml

public class Menu1 extends Fragment {
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View   v=inflater.inflate(R.layout.menu1,null);
        return v;
    }
}

menu1.xml(-menu4.xml就是图片不一样)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
>
<ImageView
        android:src="@drawable/img1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</RelativeLayout>

mian.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <fragment
            android:id="@+id/mainc"
            android:name="s.jf3q.fragment_tab.Menu1"//默认显示的页面
            android:layout_width="match_parent"
            android:layout_height="match_parent"></fragment>
    <LinearLayout
            android:layout_alignParentBottom="true"
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
        <Button
                android:layout_weight="1"
                android:id="@+id/bm1"
                android:text="m1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>
        <Button
                android:layout_weight="1"
                android:id="@+id/bm2"
                android:text="m2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>
        <Button
                android:layout_weight="1"
                android:id="@+id/bm3"
                android:text="m3"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>
        <Button
                android:layout_weight="1"
                android:id="@+id/bm4"
                android:text="m4"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>

    </LinearLayout>

</RelativeLayout>

main.java

package s.jf3q.fragment_tab;

import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentTransaction;

public class MainActivity extends AppCompatActivity {
    FragmentTransaction t;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);



        Button bm1=findViewById(R.id.bm1);
        bm1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Menu1 menu1=new Menu1();
                t= getSupportFragmentManager().beginTransaction();
                t.replace(R.id.mainc,menu1);
                t.commit();

            }
        });


        Button bm2=findViewById(R.id.bm2);
        bm2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Menu2 menu2=new Menu2();
                t= getSupportFragmentManager().beginTransaction();
                t.replace(R.id.mainc,menu2);
                t.commit();
            }
        });


        Button bm3=findViewById(R.id.bm3);
        bm3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Menu3 menu3=new Menu3();
                t= getSupportFragmentManager().beginTransaction();
                t.add(R.id.mainc,menu3);
                t.commit();

            }
        });


        Button bm4=findViewById(R.id.bm4);
        bm4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Menu4 menu4=new Menu4();
                t= getSupportFragmentManager().beginTransaction();
                t.replace(R.id.mainc,menu4);
                t.commit();
            }
        });
    }


}