Fragment

Fragment界面代码

<?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:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context="lenovo_com.fragment2.MainActivity">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:layout_marginTop="200dp"
        android:text="this is first fragment"/>


    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">

        <Button
            android:id="@+id/show"
            android:layout_marginTop="80dp"
            android:layout_width="200dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="Show next  "
            android:gravity="center"
            android:onClick="onClick"
            />
    </LinearLayout>

</LinearLayout>

<?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:id="@+id/activity_main2"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="lenovo_com.fragment2.Main2Activity">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:text="This is second fragment"
        android:textSize="20sp" />
    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>

    <Button
        android:id="@+id/bt_show"
        android:layout_marginTop="80dp"
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="Show next  "
        android:gravity="center"
        android:onClick="onClick"
        />
    

</FrameLayout>
相应的Java语句：

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

 public void onClick(View view) {
                if(view.getId()==R.id.bt_show){
                    e=true; 
                    if(a){
                        FragmentManager manager = getFragmentManager();
                        FragmentTransaction transaction = manager.beginTransaction();
                        if (secondFragment == null){
                            secondFragment = new SecondFragment();
                            transaction.replace(R.id.show,secondFragment);
                            transaction.commit();
                            a=false;    
                        } else{
                            transaction.replace(R.id.show,secondFragment);
                            transaction.commit();
                            a=false;    
                        }
                    }else{
                        Toast.makeText(this,"This is second fragment", Toast.LENGTH_SHORT).show();
                    }
                }
            }

        }
}