fragment我的理解就是有一个小的activity,也可包含布局也有生命周期,可嵌入到activity中

静态添加

在main布局添加fragment标签,这里的android:name="com.example.xyz.fragmentview.FragmentOne"这里的为继承Fragment的类

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">

   <Button
       android:id="@+id/button1"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:text="切换fragment"
       />

   <LinearLayout
       android:id="@+id/line1"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:orientation="horizontal">
      <fragment
          android:id="@+id/fragment1"
          android:name="com.example.xyz.fragmentview.FragmentOne"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          />

   </LinearLayout>



</android.support.constraint.ConstraintLayout>

在新建fragment1.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center"
    >
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="我是A Fragment"
        android:layout_gravity="center"
        />
</LinearLayout>

在新建继承Fragment的类,返回

package com.example.xyz.fragmentview;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class FragmentOne extends Fragment {
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment1,container,false);
        return view;
    }
}

这里就已经静态的添加完成了。

动态添加

在之前的基础上新建FragmenTwo类,在建fragment2.xml

public class FragmentTwo extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment2,container,false);
        return view;
    }
}

在MainActivity.java里修改代码为

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = this.findViewById(R.id.button1);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                FragmentManager fragmentManager = getSupportFragmentManager();  //获取FragmentManager
                FragmentTransaction transaction = fragmentManager.beginTransaction(); //开启一个事务
                transaction.replace(R.id.fragment1,new FragmentTwo()); //替换为FragmentTwo返回的view
                transaction.commit();  //最后提交
            }
        });
    }
}