สร้าง Fragment ขึ้นมาใหม่ชื่อ FirstFragment, SecondFragment และ ThirdFragment

ไฟล์ที่เกี่ยวข้อง

• activity_main.xml
• MainActivity.java
• fragment_first.xml
• FirstFragment.java
• fragment_second.xml
• SecondFragment.java
• fragment_third.xml
• ThirdFragment.java

activity_main.xml

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

    <GridLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginBottom="20dp">

        <Button
            android:id="@+id/button1"
            android:text="Fragment 1"
            android:textSize="16sp" />

        <Button
            android:id="@+id/button2"
            android:text="Fragment 2"
            android:textSize="16sp" />

        <Button
            android:id="@+id/button3"
            android:text="Fragment 3"
            android:textSize="16sp" />
    </GridLayout>

    <FrameLayout
        android:id="@+id/frameLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

MainActivity.java

package com.phaisarn.myapplication;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final FirstFragment f1 = FirstFragment.newInstance("First value!");
        final FirstFragment f2 = FirstFragment.newInstance("Second value!");
        final FirstFragment f3 = FirstFragment.newInstance("Third value!");

        Button button1 = findViewById(R.id.button1);
        Button button2 = findViewById(R.id.button2);
        Button button3 = findViewById(R.id.button3);

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                replaceFragment(f1);
            }
        });
        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                replaceFragment(f2);
            }
        });
        button3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                replaceFragment(f3);
            }
        });
    }

    private void replaceFragment(Fragment fragment) {
        getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.frameLayout, fragment)
                .commit();
    }
}

บรรทัดที่ 17-19 สร้าง object ของ fragment ขึ้นมาใหม่จาก static method ของ fragmentพร้อมส่งค่าที่ต้องการให้ fragment

fragment_first.xml

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

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_margin="30dp"
        android:text="Fragment #1"
        android:textSize="20sp" />

</FrameLayout>

FirstFragment.java

package com.phaisarn.myapplication;

import android.os.Bundle;

import androidx.fragment.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class FirstFragment extends Fragment {
    private static final String MESSAGE1 = "message1";

    public FirstFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_first, container, false);
        TextView textView = view.findViewById(R.id.textView1);

        String msg1 = getArguments().getString(MESSAGE1);
        textView.setText(msg1);

        return view;
    }

    public static FirstFragment newInstance(String msg1) {
        FirstFragment fragment = new FirstFragment();
        Bundle bundle = new Bundle();
        bundle.putString(MESSAGE1, msg1);
        fragment.setArguments(bundle);
        return fragment;
    }
}

บรรทัดที่ 30 สร้าง static method ชื่อ newInstance() ไว้รับค่าให้กับ fragment
บรรทัดที่ 32 การส่งค่าให้ fragment ต้องทำผ่าน Bundle
บรรทัดที่ 34 ส่งค่าให้ fragment
บรรทัดที่ 24 การรับค่าที่ส่งมาให้ fragment รับค่าด้วย getArguments
บรรทัดที่ 25 แสดงข้อความออก textview

fragment_second.xml

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

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_margin="30dp"
        android:text="Fragment #2"
        android:textSize="20sp" />

</FrameLayout>

SecondFragment.java

package com.phaisarn.myapplication;

import android.os.Bundle;

import androidx.fragment.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class SecondFragment extends Fragment {
    private static final String MESSAGE2 = "message2";

    public SecondFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_first, container, false);
        TextView textView = view.findViewById(R.id.textView1);

        String msg1 = getArguments().getString(MESSAGE2);
        textView.setText(msg1);

        return view;
    }

    public static FirstFragment newInstance(String msg1) {
        FirstFragment fragment = new FirstFragment();
        Bundle bundle = new Bundle();
        bundle.putString(MESSAGE2, msg1);
        fragment.setArguments(bundle);
        return fragment;
    }
}

fragment_third.xml

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

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_margin="30dp"
        android:text="Fragment #3"
        android:textSize="20sp" />

</FrameLayout>

ThirdFragment.java

package com.phaisarn.myapplication;

import android.os.Bundle;

import androidx.fragment.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class ThirdFragment extends Fragment {
    private static final String MESSAGE3 = "message3";

    public ThirdFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_first, container, false);
        TextView textView = view.findViewById(R.id.textView1);

        String msg1 = getArguments().getString(MESSAGE3);
        textView.setText(msg1);

        return view;
    }

    public static FirstFragment newInstance(String msg1) {
        FirstFragment fragment = new FirstFragment();
        Bundle bundle = new Bundle();
        bundle.putString(MESSAGE3, msg1);
        fragment.setArguments(bundle);
        return fragment;
    }
}