定时器完成后如何让 Viewpager 转到下一页？

Question

我目前正在制作一个锻炼应用程序，并且我制作了一个有 5 页的 Viewpager，并且具有可以正常工作的上一个和下一个按钮以及一个在活动打开后启动的一分钟倒计时计时器。我期待在计时器完成后让 Viewpager 进入下一页，在打开页面时恢复计时器，无论页面是下一页还是上一页都这样做。我是编码新手，我不知道该怎么做。如果有人向我展示代码中要更改的内容或向我展示工作代码，那就太棒了。

活动：

 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_morning);

    findViewById(R.id.imageBackMorning).setOnClickListener(v -> onBackPressed());

    countdownText = findViewById(R.id.countdownText);
    countdownButton = findViewById(R.id.countdownButton);

    countdownButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            startStop();
        }
    });

    startTimer();

    btnPrev = findViewById(R.id.prev);
    btnNext = findViewById(R.id.next);

    btnPrev.setVisibility(View.GONE);

    setupViewPager();

    pageChange();

}

private void startStop() {
    if (timerRunning) {
        stopTimer();
    } else {
        startTimer();
    }
}

private void startTimer() {
    countdownTimer = new CountDownTimer(timeLeft, 1000) {
        @Override
        public void onTick(long l) {
            timeLeft = l;
            update();
        }

        @Override
        public void onFinish() {

        }
    }.start();
    countdownButton.setText("Pause");
    timerRunning = true;

}

private void stopTimer() {
    countdownTimer.cancel();
    countdownButton.setText("Resume");
    timerRunning = false;
}

private void update() {
    int minutes = (int) timeLeft / 60000;
    int seconds = (int) timeLeft % 60000 / 1000;

    String timeLeftText;

    timeLeftText = "" + minutes;
    timeLeftText += ":";
    if (seconds < 10) timeLeftText += "0";
    timeLeftText += seconds;

    countdownText.setText(timeLeftText);
}

private void pageChange() {
    viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {
            page = position;
            switch (position) {
                case 0:
                    btnPrev.setVisibility(View.GONE);
                    btnNext.setVisibility(View.VISIBLE);
                    break;
                case 1:

                case 2:

                case 3:
                    btnPrev.setVisibility(View.VISIBLE);
                    btnNext.setVisibility(View.VISIBLE);
                    break;

                case 4:
                    btnPrev.setVisibility(View.VISIBLE);
                    btnNext.setVisibility(View.GONE);
                    break;
            }
        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }
    });
}

private void setupViewPager() {
    adapter = new Adapter(this);
    viewPager = findViewById(R.id.viewpager);
    viewPager.setAdapter(adapter);
}

public void prev(View view) {
    viewPager.setCurrentItem(viewPager.getCurrentItem() - 1, true);
}

public void next(View view) {
    viewPager.setCurrentItem(viewPager.getCurrentItem() + 1, true);
}

private class Adapter extends PagerAdapter {
    Context context;
    LayoutInflater inflater;

    public Adapter(Context context) {
        this.context = context;
    }

    // list img
    int[] list_img = {
            R.drawable.email_pic,
            R.drawable.email_pic,
            R.drawable.email_pic,
            R.drawable.email_pic,
            R.drawable.email_pic
    };

    // list judul
    int[] list_judul = {
            R.string.judul_1,
            R.string.judul_2,
            R.string.judul_3,
            R.string.judul_4,
            R.string.judul_5
    };

    // list deskripsi
    int[] list_desk = {
            R.string.desk_1,
            R.string.desk_2,
            R.string.desk_3,
            R.string.desk_4,
            R.string.desk_5
    };

    // list color bg
    int[] list_bg = {
            getResources().getColor(R.color.blue),
            getResources().getColor(R.color.white),
            getResources().getColor(R.color.blue),
            getResources().getColor(R.color.white),
            getResources().getColor(R.color.blue)

    };

    @Override
    public int getCount() {
        return list_judul.length;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return (view == object);
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        inflater = (LayoutInflater) context.getSystemService(LAYOUT_INFLATER_SERVICE);
        View view = inflater.inflate(R.layout.item_layout,container,false);
        LinearLayout linearLayout = view.findViewById(R.id.item_layout);
        ImageView imageView = view.findViewById(R.id.img);
        TextView judul = view.findViewById(R.id.judul);
        TextView desk = view.findViewById(R.id.deskripsi);

        linearLayout.setBackgroundColor(list_bg[position]);
        imageView.setImageResource(list_img[position]);
        judul.setText(list_judul[position]);
        desk.setText(list_desk[position]);
        container.addView(view);
        return view;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((LinearLayout)object);
    }
}

xml：

 <LinearLayout
    android:id="@+id/linearLayout"
    android:layout_width="match_parent"
    android:layout_height="?actionBarSize"
    android:background="@color/white"
    android:backgroundTint="@color/remain_black"
    android:gravity="center_vertical"
    android:orientation="horizontal"
    app:layout_constraintTop_toTopOf="parent">


    <ImageView
        android:id="@+id/imageBackMorning"
        android:layout_width="50dp"
        android:layout_height="45dp"
        android:paddingLeft="0sp"
        android:paddingTop="10sp"
        android:scaleX="0.9"
        android:scaleY="0.9"
        android:src="@drawable/white_arrow_back_24"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</LinearLayout>

<androidx.viewpager.widget.ViewPager
    android:id="@+id/viewpager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginTop="@dimen/_40sdp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/linearLayout"></androidx.viewpager.widget.ViewPager>


<TextView
    android:id="@+id/countdownText"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:text="01:00"
    android:textColor="@color/red"
    android:textSize="40sp"
    android:layout_marginBottom="@dimen/_8sdp"
    app:layout_constraintBottom_toTopOf="@+id/countdownButton"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent" />

<Button
    android:id="@+id/countdownButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:scaleX="1.2"
    android:scaleY="1.2"
    android:backgroundTint="@color/red"
    android:text="Start"
    android:src="@drawable/play"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    android:layout_marginBottom="@dimen/_50sdp"/>

<Button
    android:id="@+id/prev"
    android:layout_width="100dp"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:onClick="prev"
    android:text="prev"
    android:backgroundTint="@color/red"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintStart_toStartOf="parent" />

<Button
    android:id="@+id/next"
    android:layout_width="100dp"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:layout_alignParentBottom="true"
    android:onClick="next"
    android:text="next"
    android:backgroundTint="@color/red"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent" />

截图：

提前谢谢你。

Answer 1

定时器结束后让 Viewpager 跳转到下一页

当你的倒数计时器触发时，它会调用onFinish()，所以你可以在那里调用set next index。

private void startTimer() {
    countdownTimer = new CountDownTimer(timeLeft, 1000) {
        @Override
        public void onTick(long l) {
            timeLeft = l;
            update();
        }

        @Override
        public void onFinish() {
            // do something in here, like
            viewPager.setCurrentItem(viewPager.getCurrentItem() + 1, true);
            // think about what would happen if currently on the last page?
            // go back to 0, stop? reverse maybe?
        }
    }.start();
    countdownButton.setText("Pause");
    timerRunning = true;

}

当页面打开时恢复计时器

您的意思是每个页面都会有一个单独的计时器吗？在这种情况下，您需要考虑如何单独保留每个页面的计时器值。 （想想当一个页面发生变化时会发生什么，以及你是如何为每个页面保留资源和字符串的。）然后当每个页面发生变化时，为所选页面提取正确的值并从那里恢复计时器。