android - Android Studio:启动倒数计时器时应用崩溃

我制作了一个应用程序来计算比赛中的进球数(当您和 friend 一起玩并且懒得计算分数时:D)，我想创建一个倒数计时器来计算比赛时间。
当我按下开始按钮启动倒数计时器时，我的应用程序崩溃了。我有2个 Activity 。主要 Activity 是用于计算2个团队得分的代码。

这是我的第二个 Activity 代码(CountDowntimer应该在哪里):

    package com.example.robert.scorecount;

import android.os.CountDownTimer;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.util.concurrent.TimeUnit;


public class SecondActivity extends AppCompatActivity {

    Button StartButton,StopButton;
    TextView TimerText;

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

        Button StartButton = (Button) findViewById(R.id.StartButton);
        Button StopButton = (Button) findViewById(R.id.StopButton);
        TextView TimerText = (TextView) findViewById(R.id.Timer);

        TimerText.setText("00:00:00");

    final CounterClass timer = new CounterClass(3600000,1000);

        assert StartButton != null;
        StartButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                timer.start();
            }
        });


        assert StopButton != null;
        StopButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                timer.cancel();
            }
        });



    }

    public class CounterClass extends CountDownTimer{

        public CounterClass(long millisInFuture, long countDownInterval) {
            super(millisInFuture, countDownInterval);
        }



        @Override
        public void onTick(long millisUntilFinished) {
            String HourMinutesSeconds = String.format("%02d:%02d:%02d", TimeUnit.MILLISECONDS.toHours(millisUntilFinished),
                    TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(millisUntilFinished)),
                    TimeUnit.MILLISECONDS.toSeconds(millisUntilFinished) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished)));
            TimerText.setText(HourMinutesSeconds);



        }

        @Override
        public void onFinish() {
            TimerText.setText("Finished.");


        }
    }





}

这是我的布局代码:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.robert.scorecount.SecondActivity">

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Timer Settings"
        android:id="@+id/textView"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:textSize="20dp"
        android:textAlignment="center" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Start"
        android:id="@+id/StartButton"
        android:layout_marginBottom="37dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="00:00"
        android:id="@+id/Timer"
        android:textSize="30dp"
        android:layout_marginTop="88dp"
        android:layout_below="@+id/ThirtyMinMatch"
        android:layout_centerHorizontal="true" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Stop"
        android:id="@+id/StopButton"
        android:layout_above="@+id/StartButton"
        android:layout_centerHorizontal="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="30 Minutes"
        android:id="@+id/ThirtyMinMatch"
        android:layout_marginTop="24dp"
        android:layout_below="@+id/textView"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_toLeftOf="@+id/Timer"
        android:layout_toStartOf="@+id/Timer" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="1 Hour"
        android:id="@+id/OneHourMinMatch"
        android:layout_alignTop="@+id/ThirtyMinMatch"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_toRightOf="@+id/Timer"
        android:layout_toEndOf="@+id/Timer" />

</RelativeLayout>

最佳答案

您的代码:

TextView TimerText = (TextView) findViewById(R.id.Timer);

更改此行，只需删除“TextView”，它已经在顶部。

TimerText = (TextView) findViewById(R.id.Timer);