單擊按鈕時應用程序崩潰

Question

我正在嘗試做這個音樂播放器應用程序。

我為 2x2 網格布局中的每個位置創建了一個相對布局，在每個相對布局中，我放置了一個搜索欄和一個按鈕。 對於每個按鈕，我想播放不同的音樂，按鈕上方的搜索欄應該用於設置音樂位置。

此外，我使用標簽來確定按下了哪個按鈕。

完成界面后，我開始實現 onPress 方法，但它不起作用，我不確定如何指定在播放特定音樂時將處於活動狀態的搜索欄……這是我的到目前為止的代碼，在第 27 行顯示錯誤（ ImageView counter = (ImageView) view; ）並在我單擊任何按鈕時崩潰：

package com.victorpietro.musicproject;

import android.content.Context;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.Toast;

import java.util.Timer;
import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {

    int musicPlaying = 0;
    AudioManager audioManager;
    MediaPlayer mplayer;

    SeekBar scrubber;

    public void onPress(View view){

        ImageView counter = (ImageView) view;
        int tag = Integer.parseInt(counter.getTag().toString());
        Log.i("Tag", counter.getTag().toString());
        switch (tag){
            case 1:
                scrubber = (SeekBar)findViewById(R.id.seekBar);
                mplayer = MediaPlayer.create(this, R.raw.house);
                musicPlaying = 1;
                break;

            case 2:
                scrubber = (SeekBar)findViewById(R.id.seekBar2);
                mplayer = MediaPlayer.create(this, R.raw.techno);
                musicPlaying = 2;
                break;

            case 3:
                scrubber = (SeekBar)findViewById(R.id.seekBar3);
                mplayer = MediaPlayer.create(this, R.raw.deephouse);
                musicPlaying = 3;
                break;

            case 4:
                scrubber = (SeekBar)findViewById(R.id.seekBar4);
                mplayer = MediaPlayer.create(this, R.raw.chill);
                musicPlaying = 4;
                break;
        }

        scrubber.setMax(mplayer.getDuration());

        int maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
        int curVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);

        new Timer().scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run(){
                scrubber.setProgress(mplayer.getCurrentPosition());
            }
        }, 0, 100);

        scrubber.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                mplayer.seekTo(progress);
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {
                if(mplayer.isPlaying()) {
                    mplayer.pause();
                }
            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
                if(!(mplayer.isPlaying())) {
                    mplayer.start();
                }
            }
        });
    }

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

        audioManager = (AudioManager)getSystemService(Context.AUDIO_SERVICE);

    }
}

這里是 xml：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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"
    android:background="@android:color/background_dark"
    tools:context="com.victorpietro.musicproject.MainActivity">


    <TextView
        android:id="@+id/textView"
        android:layout_width="320dp"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:layout_marginBottom="200dp"
        android:layout_marginEnd="32dp"
        android:layout_marginRight="32dp"
        android:background="@android:color/black"
        android:padding="8dp"
        android:text="MUSIC STYLE PLAYER"
        android:textAlignment="center"
        android:textColor="#ffffff"
        android:textSize="26sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

    <GridLayout
        android:id="@+id/gridLayout"
        android:layout_width="fill_parent"
        android:layout_height="347dp"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:columnCount="2"
        android:rowCount="2"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/seekBar">


        <RelativeLayout
            android:id="@+id/r_layout1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_column="0"
            android:layout_columnWeight="1"
            android:layout_gravity="fill_horizontal"
            android:layout_row="0"
            android:layout_rowWeight="1">

            <Button
                android:id="@+id/button"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:layout_alignLeft="@+id/imageView"
                android:layout_alignStart="@+id/imageView"
                android:layout_centerVertical="true"
                android:onClick="onPress"
                android:tag="1"
                android:text="House" />

            <ImageView
                android:id="@+id/imageView"
                android:layout_width="150dp"
                android:layout_height="150dp"
                android:layout_above="@+id/button"
                android:layout_centerHorizontal="true"
                android:layout_marginTop="20dp"
                android:background="@android:color/background_light"
                app:srcCompat="@drawable/houseimg" />
        </RelativeLayout>

        <RelativeLayout
            android:id="@+id/r_layout2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_column="1"
            android:layout_columnWeight="1"
            android:layout_gravity="fill_horizontal"
            android:layout_row="0"
            android:layout_rowWeight="1">

            <Button
                android:id="@+id/button2"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:onClick="onPress"
                android:tag="2"
                android:text="Techno" />

            <ImageView
                android:id="@+id/imageView2"
                android:layout_width="150dp"
                android:layout_height="150dp"
                android:layout_above="@+id/button2"
                android:layout_alignLeft="@+id/button2"
                android:layout_alignStart="@+id/button2"
                android:layout_marginTop="20dp"
                android:background="@android:color/background_light"
                app:srcCompat="@drawable/technoimg" />
        </RelativeLayout>

        <RelativeLayout
            android:id="@+id/r_layout3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_column="0"
            android:layout_columnWeight="1"
            android:layout_gravity="fill_horizontal"
            android:layout_row="1"
            android:layout_rowWeight="1">

            <Button
                android:id="@+id/button3"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:onClick="onPress"
                android:tag="3"
                android:text="Deep House" />

            <ImageView
                android:id="@+id/imageView3"
                android:layout_width="150dp"
                android:layout_height="70dp"
                android:layout_above="@+id/button3"
                android:layout_alignLeft="@+id/button3"
                android:layout_alignStart="@+id/button3"
                android:layout_marginTop="20dp"
                android:background="@android:color/background_light"
                android:padding="5dp"
                app:srcCompat="@drawable/deephouseimg" />
        </RelativeLayout>


        <RelativeLayout
            android:id="@+id/r_layout4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_column="1"
            android:layout_columnWeight="1"
            android:layout_gravity="fill_horizontal"
            android:layout_row="1"
            android:layout_rowWeight="1">

            <Button
                android:id="@+id/button4"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:onClick="onPress"
                android:tag="4"
                android:text="Chill Out" />

            <ImageView
                android:id="@+id/imageView4"
                android:layout_width="150dp"
                android:layout_height="70dp"
                android:layout_above="@+id/button4"
                android:layout_alignLeft="@+id/button4"
                android:layout_alignStart="@+id/button4"
                android:layout_marginTop="20dp"
                android:background="@android:color/background_light"
                android:padding="3dp"
                app:srcCompat="@drawable/chillimg" />
        </RelativeLayout>

    </GridLayout>

    <SeekBar
        android:id="@+id/seekBar"
        android:layout_width="125dp"
        android:layout_height="wrap_content"
        android:layout_above="@+id/gridLayout"
        android:layout_marginEnd="50dp"
        android:layout_marginRight="50dp"
        android:layout_marginStart="40dp"
        android:layout_marginLeft="40dp"
        android:layout_marginTop="82dp"
        android:background="@android:color/background_light"
        app:layout_constraintBottom_toTopOf="@+id/gridLayout"
        app:layout_constraintEnd_toStartOf="@+id/seekBar2"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <SeekBar
        android:id="@+id/seekBar2"
        android:layout_width="125dp"
        android:layout_height="wrap_content"
        android:layout_above="@+id/gridLayout"
        android:layout_marginEnd="40dp"
        android:layout_marginRight="50dp"
        android:layout_marginTop="100dp"
        android:background="@android:color/background_light"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/seekBar"
        app:layout_constraintTop_toTopOf="parent" />

    <SeekBar
        android:id="@+id/seekBar3"
        android:layout_width="125dp"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginBottom="16dp"
        android:layout_marginEnd="51dp"
        android:layout_marginRight="51dp"
        android:layout_marginLeft="42dp"
        android:layout_marginStart="42dp"
        android:background="@android:color/background_light"
        app:layout_constraintBottom_toBottomOf="@+id/gridLayout"
        app:layout_constraintEnd_toStartOf="@+id/seekBar4"
        app:layout_constraintStart_toStartOf="parent" />

    <SeekBar
        android:id="@+id/seekBar4"
        android:layout_width="125dp"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginBottom="16dp"
        android:layout_marginRight="41dp"
        android:layout_marginEnd="41dp"
        android:background="@android:color/background_light"
        app:layout_constraintBottom_toBottomOf="@+id/gridLayout"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/seekBar3" />

</android.support.constraint.ConstraintLayout>

錯誤日志：

致命異常：主進程：com.victorpietro.musicproject，PID：12799 java.lang.IllegalStateException：無法在 android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293) 處執行 android:onClick 的方法在 android.view.View.performClick(View.java:6294) 在 android.view.View$PerformClick.run(View.java:24770) 在 android.os.Handler.handleCallback(Handler.java:790) 在 android。 os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:6494) at java.lang.reflect.Method .invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 引起：java .lang.reflect.InvocationTargetException at java.lang.reflect.Method.invoke(Native Method) at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) at android.view.View.performClick(View.java:6294) at android.view.View$PerformClick.run(View.java:24770) at android.os.Handler.handleCallback(Handler.java:790) at android.os .Handler.dispatchMessage(Handler.java:99) 在 android.os.Looper.loop(Looper.java:164) 在 android.app.ActivityThread.main(ActivityThread.java:6494) 在 java.lang.reflect.Method。 invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 引起：java。 lang.ClassCastException: android.support.v7.widget.AppCompatButton 不能被投射到 android.widget.ImageView at com.victorpietro.musicproject.MainActivity.onPress(MainActivity.java:27) at java.lang.reflect.Method.invoke(本機方法）在 android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 在 android.view.View.performClick(View.java:6294) 在 android.view.View$PerformClick.run( View.java:24770) 在 android.os.Handler.handleCallback(Handler.java:790) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread .main(ActivityThread.java:6494) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) at com.android.internal .os.ZygoteInit.main(ZygoteInit.java:807)

Answer 1

這將在這里解決問題！ 根本不要接觸您的 xml，並在您的應用程序的 Java 代碼端執行這些操作

 public void onPress(View view){

    // get the view item's ID which in your case will be the button's id and use a switch case on it

    int id = view.getId()

    switch (id){
        case R.id.button:
            scrubber = (SeekBar)findViewById(R.id.seekBar);
            mplayer = MediaPlayer.create(this, R.raw.house);
            musicPlaying = 1;
            break;

        case R.id.button2:
            scrubber = (SeekBar)findViewById(R.id.seekBar2);
            mplayer = MediaPlayer.create(this, R.raw.techno);
            musicPlaying = 2;
            break;

       case R.id.button3:
            scrubber = (SeekBar)findViewById(R.id.seekBar3);
            mplayer = MediaPlayer.create(this, R.raw.deephouse);
            musicPlaying = 3;
            break;

       case R.id.button4:
            scrubber = (SeekBar)findViewById(R.id.seekBar4);
            mplayer = MediaPlayer.create(this, R.raw.chill);
            musicPlaying = 4;
            break;
    }

Answer 2

您的 logcat 清楚地說明了錯誤是什么。 請通過 logcat 並找出哪一行。 錯誤是。 這里

java.lang.ClassCastException: android.support.v7.widget.AppCompatButton cannot be cast to android.widget.ImageView at com.victorpietro.musicproject.MainActivity.onPress(MainActivity.java:27)

它在第一行說。 27 您使用了AppCompatButton但在初始化它時您使用了 ImageView。 您需要使用AppCompatButton而不是 imageView。 因此，而不是使用

 ImageView counter = (ImageView) view;

使用Button counter=(Button) view; 很可能它應該工作。