Fragment基本描述（二）

 

上一篇我们讲解了基本的fragmen使用，这一章节我们讲解如何动态加载fragment。下一节我们讲解的是fragment的生命周期。

 

本示例通过一个fragment启动另一个fragment。

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button butotn = findViewById(R.id.butotn);
        butotn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                replaceFragment(new FragmenRight());
            }
        });
    }

    private void replaceFragment(Fragment fragment) {
        FragmentManager supportFragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = supportFragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.fl, fragment);
        fragmentTransaction.commit();
    }
}

对应的xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="horizontal"
    tools:context="com.example.administrator.myfragment2.MainActivity">

    <fragment
        android:id="@+id/lift"
        android:name="com.example.administrator.myfragment2.FragmentLift"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1" />

    <FrameLayout
        android:id="@+id/fl"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"></FrameLayout>

</LinearLayout>

FragmentLift：

public class FragmentLift extends Fragment {
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_lift, container, false);

        return view;
    }


}

对应的xml：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000000">

    <Button
        android:id="@+id/butotn"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="左侧"
        android:gravity="center_horizontal"
        android:textColor="#ffffff" />


</android.support.constraint.ConstraintLayout>

FragmenRight：

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

对应的xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffff">
    <TextView
        android:gravity="center_horizontal"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="右侧"
        android:textColor="#000000"/>

</android.support.constraint.ConstraintLayout>

addToBackStack(null)的使用

通过调用 addToBackStack(null)，可以将替换事务保存到返回栈，以便用户能够通过按返回按钮撤消事务并回退到上一片段。

在MainActivity中：

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button butotn = findViewById(R.id.butotn);
        Button button = findViewById(R.id.button);
        butotn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                replaceFragment(new FragmenRight());
            }
        });
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                replaceFragment2(new FragmenRight());
            }
        });
    }

    private void replaceFragment(Fragment fragment) {
        FragmentManager supportFragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = supportFragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.fl, fragment);
        fragmentTransaction.commit();
    }

    private void replaceFragment2(Fragment fragment) {
        FragmentManager supportFragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = supportFragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.fl, fragment);
        fragmentTransaction.addToBackStack(null);
        fragmentTransaction.commit();
    }
}

对应的xml：

同上

FragmentLift：

同上

FragmentLift对应的xml：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000000">

    <Button
        android:id="@+id/butotn"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="左侧"
        android:gravity="center_horizontal"
        android:textColor="#ffffff" />
    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="跳转"/>


</android.support.constraint.ConstraintLayout>

转发表明出处：https://blog.csdn.net/qq_35698774/article/details/106426102

点击下载源码

感谢：https://developer.android.google.cn/guide/components/fragments

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