Android学习笔记Tab代替ActionBar做的顶部导航

1、先准备5个Fragement作为标签页

package com.lzp.youdaotab;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

public class Fragment1 extends Fragment {

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater,
                             @Nullable ViewGroup container,
                             @Nullable Bundle savedInstanceState) {

        return inflater.inflate(R.layout.fragment_1,null);
    }
}

其余4个同上

2、对应给每个fragment添加布局

<?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">
    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/fragment_1"
        android:scaleType="fitXY"/>
</LinearLayout>

3、编写MyTabListener实现标签页的切换

package com.lzp.youdaotab;

import android.app.Activity;

import androidx.appcompat.app.ActionBar;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentTransaction;

/**
 * 实现标签页的切换
 */
public class MyTabListener implements ActionBar.TabListener {

    private final Activity activity; //用于指定要加载Fragment的Activity
    private final Class aClass;     //用于指定要加载的Fragment所对应的类
    private Fragment fragment;  //定义Fragment对象

    public MyTabListener(Activity activity, Class aClass) {
        this.activity = activity;
        this.aClass = aClass;
    }
    /***被选择时***/
    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
        if(fragment == null){
            fragment = Fragment.instantiate(activity,aClass.getName());
            ft.add(android.R.id.content,fragment,null);
        }
        ft.attach(fragment);//显示新页面
    }
    /**退出选中状态**/
    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {
        if(fragment!=null){
            ft.detach(fragment);//删除旧页面
        }
    }
    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {

    }
}

4、编写MainActivity加载样式

package com.lzp.youdaotab;

import androidx.appcompat.app.ActionBar;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    private static final String[] tabStrs = {
            "词典",
            "百科",
            "翻译",
            "发现",
            "我的"
    };

    private static final Class[] fragments = {
            Fragment1.class,
            Fragment2.class,
            Fragment3.class,
            Fragment4.class,
            Fragment5.class
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //设置ActionBar为选项卡模式，并将标签页添加到ActionBar中
        ActionBar actionBar = getSupportActionBar();//获取ActionBar对象
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); //设置ActionBar采用选项卡模式
        actionBar.setDisplayOptions(0,ActionBar.DISPLAY_SHOW_TITLE);//隐藏标题栏
        //把各个标签页添加到ActionBar中
        for(int i=0;i<tabStrs.length;i++){
            actionBar.addTab(actionBar.newTab().
                    setText(tabStrs[i]).setTabListener(new MyTabListener(this, fragments[i])));//添加标签页
        }
    }
}

效果：