如何使用 Android ViewPager?
在进入示例之前,我们应该了解 Android 中的 ViewPager 是什么。ViewPager 位于 Android 的 Support Library 中,使用 ViewPager 可以切换片段。
此示例演示了如何使用 Android ViewPager。
步骤 1 - 在 Android Studio 中创建一个新项目,转到文件 ⇒ 新建项目,并填写所有必需的详细信息以创建新项目。
步骤 2 - 在 build.gradle 中添加以下代码。
apply plugin: 'com.android.application'
android {
compileSdkVersion 28
defaultConfig {
applicationId "com.example.andy.myapplication"
minSdkVersion 19
targetSdkVersion 28
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:28.0.0'
implementation 'com.android.support:design:28.0.0'
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}步骤 3 - 将以下代码添加到 res/layout/activity_main.xml。
<?xml version = "1.0" encoding = "utf-8"?> <android.support.design.widget.CoordinatorLayout xmlns:android = "http://schemas.android.com/apk/res/android" xmlns:app = "http://schemas.android.com/apk/res-auto" android:layout_width = "match_parent" android:layout_height = "match_parent"> <android.support.design.widget.AppBarLayout android:layout_width = "match_parent" android:layout_height = "wrap_content" android:theme = "@style/ThemeOverlay.AppCompat.Dark.ActionBar"> <android.support.v7.widget.Toolbar android:id = "@+id/toolbar" android:layout_width = "match_parent" android:layout_height = "?attr/actionBarSize" android:background = "?attr/colorPrimary" app:layout_scrollFlags = "scroll|enterAlways" app:popupTheme = "@style/ThemeOverlay.AppCompat.Light" /> <android.support.design.widget.TabLayout android:id = "@+id/tabs" android:layout_width = "match_parent" android:layout_height = "wrap_content" app:tabMode = "fixed" app:tabGravity = "fill"/> </android.support.design.widget.AppBarLayout> <android.support.v4.view.ViewPager android:id = "@+id/viewpager" android:layout_width = "match_parent" android:layout_height = "match_parent" app:layout_behavior = "@string/appbar_scrolling_view_behavior" /> </android.support.design.widget.CoordinatorLayout>
步骤 4 - 将以下代码添加到 src/MainActivity.java
package com.example.andy.myapplication;
import android.annotation.TargetApi;
import android.os.Build;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private ViewPager viewPager;
private Toolbar toolbar;
private TabLayout tabLayout;
@TargetApi(Build.VERSION_CODES.O)
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
tabLayout = findViewById(R.id.tabs);
viewPager = findViewById(R.id.viewpager);
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFragment(new OneFragment(), "ONE");
adapter.addFragment(new TwoFragment(), "TWO");
viewPager.setAdapter(adapter);
tabLayout.setupWithViewPager(viewPager);
}
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mList = new ArrayList<>();
private final List<String> mTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager supportFragmentManager) {
super(supportFragmentManager);
}
@Override
public Fragment getItem(int i) {
return mList.get(i);
}
@Override
public int getCount() {
return mList.size();
}
public void addFragment(Fragment fragment, String title) {
mList.add(fragment);
mTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
return mTitleList.get(position);
}
}
}步骤 5 - 将以下代码添加到 src/OneFragment.java
package com.example.andy.myapplication;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class OneFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View v= inflater.inflate(R.layout.fragment_one, container, false);
TextView textView=v.findViewById(R.id.text);
textView.setText("First Fragment");
return v;
}
}步骤 6 - 将以下代码添加到 src/TwoFragment.java
package com.example.andy.myapplication;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class TwoFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View v= inflater.inflate(R.layout.fragment_one, container, false);
TextView textView=v.findViewById(R.id.text);
textView.setText("Second Fragment");
return v;
}
}步骤 7 - 将以下代码添加到 res/layout/fragment_one.xml。
<?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"> <TextView android:id="@+id/text" android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="center" android:textSize="20sp" /> </LinearLayout>
步骤 8 - 将以下代码添加到 styles.xml。
<resources> <!-- Base application theme. --> <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar"> <!-- Customize your theme here. --> <item name = "windowNoTitle">true</item> <item name = "windowActionBar">false</item> <item name="colorPrimary">@color/colorPrimary</item> <item name="colorPrimaryDark">@color/colorPrimaryDark</item> <item name="colorAccent">@color/colorAccent</item> </style> </resources>
让我们尝试运行您的应用程序。我假设您已将您的实际 Android 移动设备连接到您的计算机。要从 Android Studio 运行应用程序,请打开您项目中的一个活动文件,然后单击工具栏中的运行
图标。选择您的移动设备作为选项,然后检查您的移动设备,它将显示您的默认屏幕 -

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