day4

底部导航栏的实现

布局代码

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


    <LinearLayout
        android:id="@+id/tab_menu"
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:orientation="horizontal"
        android:layout_alignParentBottom="true">

        <TextView
            android:id="@+id/txt_deal"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:background="@drawable/tab_menu_bg"

            android:drawableTop="@drawable/tab_menu_deal"
            android:gravity="center"
            android:textColor="@drawable/tab_menu_deal_text"
            android:text="购买"/>

        <TextView
            android:id="@+id/txt_poi"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:background="@drawable/tab_menu_bg"

            android:drawableTop="@drawable/tab_menu_poi"
            android:gravity="center"
            android:textColor="@drawable/tab_menu_deal_text"
            android:text="消息"/>

        <TextView
            android:id="@+id/txt_more"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:background="@drawable/tab_menu_bg"

            android:drawableTop="@drawable/tab_menu_show"
            android:gravity="center"
            android:textColor="@drawable/tab_menu_deal_text"

            android:text="show"/>
        <TextView
            android:id="@+id/txt_user"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:background="@drawable/tab_menu_bg"

            android:drawableTop="@drawable/tab_menu_user"
            android:gravity="center"
            android:textColor="@drawable/tab_menu_deal_text"
            android:text="我的"/>


    </LinearLayout>

    <View
        android:id="@+id/div_tab_bar"
        android:layout_width="match_parent"
        android:layout_height="2dp"
        android:background="#000000"
        android:layout_above="@id/tab_menu"/>

    <FrameLayout
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginBottom="0.01dp"
        android:layout_above="@id/tab_menu"
        android:background="#F2FBEF">
    </FrameLayout>

</RelativeLayout>

这里我的想法是用四个fragment的切换来实现

在HomeActivity中定义四个Fragment，首先通过transaction.hide把四个全部隐藏，然后设置点击事件，被点中的变成true然后显示

package com.example.expressdelivery;

import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.FrameLayout;
import android.widget.TextView;

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

import Home.BuyFragment;
import Home.MessageFragment;
import Home.MyFragment;
import Home.ShowFragment;

public class HomeActivity extends AppCompatActivity {
    private TextView topBar;
    private TextView tabDeal;
    private TextView tabPoi;
    private TextView tabMore;
    private TextView tabUser;

    private FrameLayout ly_content;
    private BuyFragment f1;
    private MessageFragment f2;
    private MyFragment f4;
    private ShowFragment f3;
    private FragmentManager fragmentManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_home);
        tabDeal = findViewById(R.id.txt_deal);
        tabPoi = findViewById(R.id.txt_poi);
        tabUser = findViewById(R.id.txt_user);
        tabMore =findViewById(R.id.txt_more);
        ly_content =  findViewById(R.id.fragment_container);

        setListeners();
    }

    private void setListeners() {
        OnClick onClick=new OnClick();

        tabDeal.setOnClickListener(onClick);
        tabMore.setOnClickListener(onClick);
        tabUser.setOnClickListener(onClick);
        tabPoi.setOnClickListener(onClick);
    }
    public void selected(){
        tabDeal.setSelected(false);
        tabMore.setSelected(false);
        tabPoi.setSelected(false);
        tabUser.setSelected(false);
    }

    //隐藏所有Fragment
    public void hideAllFragment( androidx.fragment.app.FragmentTransaction transaction){
        if(f1!=null){
            transaction.hide(f1);
        }
        if(f2!=null){
            transaction.hide(f2);
        }
        if(f3!=null){
            transaction.hide(f3);
        }
        if(f4!=null){
            transaction.hide(f4);
        }
    }
    private class OnClick implements View.OnClickListener {
        public void onClick(View v) {
            androidx.fragment.app.FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
            hideAllFragment(transaction);
            switch (v.getId()) {
                case R.id.txt_deal:
                    selected();
                    tabDeal.setSelected(true);
                    if (f1 == null) {
                        f1 = new BuyFragment();
                        transaction.add(R.id.fragment_container, f1);
                    } else {
                        transaction.show(f1);
                    }
                    break;

                case R.id.txt_poi:
                    selected();
                    tabPoi.setSelected(true);
                    if (f2 == null) {
                        f2 = new MessageFragment();
                        transaction.add(R.id.fragment_container, f2);
                    } else {
                        transaction.show(f2);
                    }
                    break;

                case R.id.txt_more:
                    selected();
                    tabMore.setSelected(true);
                    if (f3 == null) {
                        f3 = new ShowFragment();
                        transaction.add(R.id.fragment_container, f3);
                    } else {
                        transaction.show(f3);
                    }
                    break;

                case R.id.txt_user:
                    selected();
                    tabUser.setSelected(true);
                    if (f4 == null) {
                        f4 = new MyFragment();
                        transaction.add(R.id.fragment_container, f4);
                    } else {
                        transaction.show(f4);
                    }
                    break;
            }

            transaction.commit();
        }

    }
}

然后建立四个fragment也就是购买、消息、我的、社区四个。