检索 TextView.getText() 以设置带有开始按钮的 CountDownTimer

Question

我正处于 Android 编程冒险的开端，刚刚能够在屏幕视图之间进行交流。所以我的下一步是成功地从 TextView 中提取文本（由对话框设置）并使用开始按钮运行基于用户 selected 对话框的计时器（默认为当前分钟时钟的值）。

这是您在 screen 上看到的内容。

显示对话框中 selection 的 TextView。
启动对话框 TimePicker 对话框并重置启动按钮的选择器按钮。
一个开始按钮，它（应该）读取 TextView、禁用自身并根据从 TextView 字符串中提取的 Long 开始一个 CountDownTimer。
一个调试 TextView，向我显示系统实际看到的内容。

整个 activity 由一个 Java 文件组成，其中声明了两个类，当然还有一个 XML。每次我单击我的开始按钮时，尽管 Debug TextView 显示我正确地提取了计时器立即完成的秒数的 Long 值。我可以从我的调试 TextView 中看到，当我 select 说.. 08:26 时，pSecondsLeft=26 应该..但是计时器仍然没有从 26 开始倒计时。我看不到我的错误。

这是第一个XML。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_gravity="center"
              android:orientation="vertical">
    <TextView android:id="@+id/timeDisplay"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_gravity="center_horizontal"
              android:text="Time will appear here after being selected"
              android:textSize="30sp"/>
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button android:id="@+id/pickTime"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:text="Change the time"/>

        <Button android:id="@+id/startTimer"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:text="Start the time"
                />

    </LinearLayout>

    <TextView android:id="@+id/timeRemaining"
              android:layout_height="wrap_content"
              android:layout_width="wrap_content"
              android:layout_gravity="center_horizontal"
              android:textSize="30sp"
              android:text="Time Remaining"
              />


</LinearLayout>

这是我的主要 Activity。

package com.stembo.android.botskooltimepickertutorial;

import java.util.Calendar;
import java.util.StringTokenizer;

import android.app.Activity;
import android.app.Dialog;
import android.app.TimePickerDialog;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.TimePicker;
import android.widget.Toast;

public class TimePickerActivity extends Activity {
    /** Private members of the class */
    private TextView displayTime;
    private Button pickTime;
    private Button startTimer;
    private TextView timeRemaining;

    private int pMinutesLeft;
    private int pSecondsLeft;
    /** This integer will uniquely define the
     * dialog to be used for displaying time picker.*/
    static final int TIME_DIALOG_ID = 0;

    /** Callback received when the user "picks" a time in the dialog */
    private TimePickerDialog.OnTimeSetListener mTimeSetListener =
            new TimePickerDialog.OnTimeSetListener() {
                public void onTimeSet(TimePicker view, int minLeft, int secLeft) {
                    pMinutesLeft = minLeft;
                    pSecondsLeft = secLeft;
                    updateDisplay();
                    displayToast();
                }
            };

    /** Updates the time in the TextView */
    private void updateDisplay() {
        displayTime.setText(
                new StringBuilder()
                        .append(pad(pMinutesLeft)).append(":")
                        .append(pad(pSecondsLeft)));
    }

    /** Displays a notification when the time is updated */
    private void displayToast() {
        Toast.makeText(this, new StringBuilder().append("Time choosen is ")
                .append(displayTime.getText()),   Toast.LENGTH_SHORT).show();

    }

    /** Add padding to numbers less than ten */
    private static String pad(int c) {
        if (c >= 10)
            return String.valueOf(c);
        else
            return "0" + String.valueOf(c);
    }

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        /** Capture our View elements */
        displayTime = (TextView) findViewById(R.id.timeDisplay);
        pickTime = (Button) findViewById(R.id.pickTime);
        startTimer = (Button) findViewById(R.id.startTimer);
        timeRemaining = (TextView) findViewById(R.id.timeRemaining);

        /** Listener for click event of the pick button */
        pickTime.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                startTimer.setEnabled(true);
                showDialog(TIME_DIALOG_ID);
            }
        });

        /**Listener for click event of the start button */
        startTimer.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                startTimer.setEnabled(false);
                StringTokenizer st = new StringTokenizer(displayTime.getText().toString(), ":");
                while (st.hasMoreElements()){
                    st.nextElement();
                    long pSecondsTimer = Long.parseLong(st.nextToken());
                }
                timeRemaining.setText(displayTime.getText()+" Token="+ pSecondsLeft);
                long oneSecondInterval = 1000;
                MyCount counter = new MyCount(pSecondsLeft, oneSecondInterval);
                counter.start();
            }
        });

        /** Get the current time */
        final Calendar cal = Calendar.getInstance();
        pMinutesLeft = cal.get(Calendar.HOUR_OF_DAY);
        pSecondsLeft = cal.get(Calendar.MINUTE);

        /** Display the current time in the TextView */
        updateDisplay();
    }

    /** Create a new dialog for time picker */

    @Override
    protected Dialog onCreateDialog(int id) {
        switch (id) {
            case TIME_DIALOG_ID:
                return new TimePickerDialog(this,
                        mTimeSetListener, pMinutesLeft, pSecondsLeft, true);
        }
        return null;
    }

    public class MyCount extends CountDownTimer {
        public MyCount(long pSecondsLeft, long countDownInterval){
            super(pSecondsLeft, countDownInterval);
        }

        @Override
        public void onTick(long pSecondsTimer){
            displayTime.setText("Time remaining: " + pSecondsLeft);
        }

        @Override
        public void onFinish(){
            displayTime.setText("Countdown Complete!");
        }
    }
}

这是我遇到问题的“开始”按钮代码，它在主程序中 Activity 但可能更容易被排除在外。

/**Listener for click event of the start button */
        startTimer.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                startTimer.setEnabled(false);
                StringTokenizer st = new StringTokenizer(displayTime.getText().toString(), ":");
                while (st.hasMoreElements()){
                    st.nextElement();
                    long pSecondsTimer = Long.parseLong(st.nextToken());
                }
                timeRemaining.setText(displayTime.getText()+" Token="+ pSecondsLeft);
                long oneSecondInterval = 1000;
                MyCount counter = new MyCount(pSecondsLeft, oneSecondInterval);
                counter.start();
            }
        });

Answer 1

您从 TimePickerDialog.OnTimeSetListener 返回的值似乎存在误解。它给你小时和分钟，但你期待的是分钟和秒。对于来自您在 onCreate 上使用的日历的值也是如此。

也就是说，如果您仍然尝试使用 TimePickerDialog 来获取分钟和秒，并且完全理解您正在重新解释这些值，则需要乘以"seconds" 您从选择器收到的数量增加 1000 以获得一个可以提供给 CountDownTimer 的毫秒单位。

MyCount counter = new MyCount(pSecondsLeft * 1000, oneSecondInterval);

Answer 2

我认为这是因为您没有在每次报价时从 pSecondsLeft 变量中减去

public class MyCount extends CountDownTimer {
        public MyCount(long pSecondsLeft, long countDownInterval){
            super(pSecondsLeft, countDownInterval);
        }

        @Override
        public void onTick(long pSecondsTimer){
            displayTime.setText("Time remaining: " + pSecondsLeft);
            pSecondsLeft --;           
        }

        @Override
        public void onFinish(){
            displayTime.setText("Countdown Complete!");
        }
    }

检索 TextView.getText() 以设置带有开始按钮的 CountDownTimer

Retrieving TextView.getText() to set a CountDownTimer with a Start Button

java

android

stringtokenizer

countdowntimer