android之TabLayout介绍

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TabLayout

TabLayout是Android support中的一个控件android.support.design.widget.TabLayout，Google在升级了AndroidX之后，将TabLayout迁移到material包下面去了com.google.android.material.tabs.TabLayout，原来的support下面的TabLayout从API 29开始就不再维护了。

所以如果项目已经升级了AndroidX，建议直接使用后者。

TabLayout一般结合ViewPager+Fragment的使用实现滑动的标签选择器。

实战

activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
    tools:context=".MainActivity">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="667dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.100000024"/>

        <androidx.viewpager.widget.ViewPager
            android:id="@+id/view_pager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_constraintTop_toBottomOf="@+id/tab_layout" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java:

package com.exmple.tabloayout;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentPagerAdapter;
import androidx.viewpager.widget.ViewPager;

import android.os.Bundle;

import com.google.android.material.tabs.TabLayout;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private String[] tabs = {"tab1", "tab2", "tab3"};
    private List<TabFragment> tabFragmentList = new ArrayList<>();

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TabLayout tabLayout = findViewById(R.id.tab_layout);
        ViewPager viewPager = findViewById(R.id.view_pager);
        //添加tab
        for (int i = 0; i < tabs.length; i++) {
            tabLayout.addTab(tabLayout.newTab().setText(tabs[i]));
            tabFragmentList.add(TabFragment.newInstance(tabs[i]));
        }

        viewPager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager(), FragmentPagerAdapter.BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT) {
            @NonNull
            @Override
            public Fragment getItem(int position) {
                return tabFragmentList.get(position);
            }

            @Override
            public int getCount() {
                return tabFragmentList.size();
            }

            @Nullable
            @Override
            public CharSequence getPageTitle(int position) {
                return tabs[position];
            }
        });

        //设置TabLayout和ViewPager联动
        tabLayout.setupWithViewPager(viewPager,false);
    }
}

fragment_tab.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    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">

    <TextView
        android:id="@+id/tv_bg"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView" />
</androidx.constraintlayout.widget.ConstraintLayout>

TabFragment.java:

package com.exmple.tabloayout;

import android.graphics.Color;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

public class TabFragment extends Fragment {
    public static TabFragment newInstance(String label) {
        Bundle args = new Bundle();
        args.putString("label", label);
        TabFragment fragment = new TabFragment();
        fragment.setArguments(args);
        return fragment;
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_tab, container, false);
    }

    @Override
    public void onStart() {
        super.onStart();
        String label = getArguments().getString("label");
        TextView text = getView().findViewById(R.id.tv_bg);
        text.setText(label);
        text.setBackgroundColor(Color.rgb((int)(Math.random() * 255), (int)(Math.random() * 255), (int)(Math.random() * 255)));
    }
}

执行结果：

image.png