在Activity上載入Fragment實現點選切換Fragment

沒有ViewPager的幫助，單憑Fragment實現滑動比較困難，這裡我就只給大家說一下如何實現點選切換。
首先是xml的佈局：
activity_main.xml

<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"
    tools:context="com.example.wtl.bk1.MainActivity"
    android:orientation="vertical">

    <LinearLayout
        android:id="@+id/acttitle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:background
 
="#82FFF0">

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="center"
            android:layout_gravity="center"
            android:orientation="vertical">
 


            <TextView   //這裡是點選事件1
                android:id="@+id/frag1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="關注"
                android:paddingBottom="5dp"
                android:paddingTop="10dp"
                android:textSize="20sp"
                android:textColor="#E51C23"/>

        </LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="center"
            android:orientation="vertical"
            android:layout_gravity="center">

            <TextView    //這裡是點選事件2
                android:id="@+id/frag2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="推薦"
                android:paddingBottom="5dp"
                android:paddingTop="10dp"
                android:textSize="20sp"
                android:textColor="#343434"/>

        </LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="center"
            android:layout_gravity="center"
            android:orientation="vertical">

            <TextView   //這裡是點選事件3
                android:id="@+id/frag3"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="同城"
                android:paddingBottom="5dp"
                android:paddingTop="10dp"
                android:textSize="20sp"
                android:textColor="#343434"/>

        </LinearLayout>

    </LinearLayout>

    <FrameLayout    //FrameLayout載入你想要加入的Fragment
        android:id="@+id/frag"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

這裡我寫了一個recyclerview讓他在不同的介面顯示不同的內容，如果有需要則用三個介面分別載入
recyclerview.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycleview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

最後是recyclerview的內容：(只有一個簡單的textview)
recycler.card:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center">

    <TextView
        android:id="@+id/text"
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="26sp" />

</LinearLayout>

接下來是實現三個Fragment：
對應recycler_card檔案的類：
Text.java:

public class Text {

    private String text; 

    public Text(String text) {
        this.text = text;
    }

    public String getText() {
        return text;
    }
}

recyclerview的介面卡:

public class TextAdapter extends RecyclerView.Adapter<TextAdapter.ViewHolder> {

    private List<Text> textList;   //儲存Text物件的list
    private Context context;       //獲取fragment的context

    public TextAdapter(List<Text> textList,Context context) {
        this.textList = textList;
        this.context = context;
    }
    @Override
    public TextAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        //傳入recyclerview的佈局檔案
        View view = LayoutInflater.from(context).inflate(R.layout.recycler_card,null,false);
        ViewHolder viewHolder = new ViewHolder(view);//為ViewHolder新增view
        return viewHolder;
    }
    @Override
    public void onBindViewHolder(final TextAdapter.ViewHolder holder, int position) {
        /*
        * 獲取當前位置的物件
        * */
        final Text text = textList.get(position);
        /*
        * 為textview新增資料
        * */
        holder.text.setText(text.getText());
    }
    @Override
    public int getItemCount() {
        return textList.size();
    }
    static class ViewHolder extends RecyclerView.ViewHolder { //建立一個繼承RecyclerView.ViewHolder的類
        TextView text;  //佈局檔案中的控制元件
        public ViewHolder(View itemView) {
            super(itemView);
            text = (TextView) itemView.findViewById(R.id.text);
        }
    }
}

分別實現三個Fragment，這裡只給大家展示一個，其他的都一樣只是載入內容不同：
Fragment1：

public class Fragment1 extends Fragment {

    private List<Text> list = new ArrayList<>();
    private RecyclerView recycleview;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.recyclerview,container,false);//給Fragment載入介面
        init();
        recycleview = (RecyclerView) view.findViewById(R.id.recycleview);  //獲取xml檔案的recyclerview
        LinearLayoutManager manager = new LinearLayoutManager(getContext());  //給recyclerview設定線性佈局
        recycleview.setLayoutManager(manager);  //將線性佈局載入到recyclerview中
        TextAdapter adapter = new TextAdapter(list,getContext());  //設定你寫的介面卡
        recycleview.setAdapter(adapter); //載入
        return view;
    }
    //給list新增資料
    private void init() {
        Text text = new Text("頁面1");
        list.add(text);
    }
}

最後是在activity中載入三個Fragment
MainActivity.java:

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    //三個載入的fragment
    private Fragment1 fragment1;
    private Fragment2 fragment2;
    private Fragment3 fragment3;

    //三個對應的按鈕
    private TextView frag1;
    private TextView frag2;
    private TextView frag3;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Montior();
        change_fragment(0);//選擇fragment
    }

    //從xml中獲取所有部件
    private void Montior() {
        frag1 = (TextView) findViewById(R.id.frag1);
        frag2 = (TextView) findViewById(R.id.frag2);
        frag3 = (TextView) findViewById(R.id.frag3);

        frag1.setOnClickListener(this);
        frag2.setOnClickListener(this);
        frag3.setOnClickListener(this);
    }

    //三個按鈕的點選事件
    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.frag1:
                change_fragment(0);
                //改變點選時Textview的顏色
                frag1.setTextColor(0xffE51C23);
                frag2.setTextColor(0xff343434);
                frag3.setTextColor(0xff343434);
                break;
            case R.id.frag2:
                change_fragment(1);

                frag1.setTextColor(0xff343434);
                frag2.setTextColor(0xffE51C23);
                frag3.setTextColor(0xff343434);
                break;
            case R.id.frag3:
                change_fragment(2);

                frag1.setTextColor(0xff343434);
                frag2.setTextColor(0xff343434);
                frag3.setTextColor(0xffE51C23);
                break;
        }
    }

    private void change_fragment(int x) {
        FragmentManager manager = getSupportFragmentManager();  //初始化FragmentManager，獲取v4包所支援的fragment
        FragmentTransaction transaction = manager.beginTransaction(); //初始化FragmentTransaction
        hide_fragment(transaction);//隱藏當前fragment
        switch (x) {
            case 0:
                if(fragment1 == null) {
                    fragment1 = new Fragment1();  //如果fragment1未初始化，進行初始化
                    transaction.add(R.id.frag,fragment1); //將fragment1和對應的佈局加入棧中
                } else {  
                    transaction.show(fragment1);  //如果fragment1已經初始化，則展示
                }
                break;
            case 1:
                if(fragment2 == null) {
                    fragment2 = new Fragment2();
                    transaction.add(R.id.frag,fragment2);
                } else {
                    transaction.show(fragment2);
                }
                break;
            case 2:
                if(fragment3 == null) {
                    fragment3 = new Fragment3();
                    transaction.add(R.id.frag,fragment3);
                } else {
                    transaction.show(fragment3);
                }
                break;
        }
        transaction.commit();//之前對FragmentTransaction進行新增展示等操作，這裡呼叫commit進行提交
    }

    //如果fragment不為空則隱藏
    private void hide_fragment(FragmentTransaction transaction) {
        if(fragment1 != null) {
            transaction.hide(fragment1);
        }
        if(fragment2 != null) {
            transaction.hide(fragment2);
        }
        if(fragment3 != null) {
            transaction.hide(fragment3);
        }
    }
}

現在已經可以通過點選切換fragment了，但如果想要實現滑動效果，則還是要用到ViewPager，這裡就不給大家詳述了。