单击按钮时应用程序崩溃
App is crashing when clicking button
我正在尝试做这个音乐播放器应用程序。
我在 2x2 网格布局中为每个位置创建了一个相对布局，在每个相对布局中，我放置了一个搜索栏和一个按钮。我想为每个按钮播放不同的音乐，按钮上方的搜索栏应该用于设置音乐位置。
此外，我使用标签来确定按下了哪个按钮。
完成界面后，我开始实现 onPress 方法，但它无法正常工作，而且我不确定如何指定播放特定音乐时将激活的搜索栏。 .. 到目前为止，这是我的代码，在第 27 行 ( ImageView counter = (ImageView) view; ) 中显示错误，当我单击任何按钮时崩溃：
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);
}
}
这里是 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>
错误日志：
FATAL EXCEPTION: main
Process: com.victorpietro.musicproject, PID: 12799
java.lang.IllegalStateException: Could not execute method for
android:onClick
at
android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:6294)
at android.view.View$PerformClick.run(View.java:24770)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
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$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at
android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:6294)
at android.view.View$PerformClick.run(View.java:24770)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at
com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.ClassCastException:
android.support.v7.widget.AppCompatButton cannot be cast to
android.widget.ImageView
at
com.victorpietro.musicproject.MainActivity.onPress(MainActivity.java:27)
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)
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)
这里就可以了！根本不要触摸您的 xml 并在您应用的 java 代码端执行这些操作
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;
}
您的 logcat 清楚地说明了错误是什么。请浏览 logcat 并找出在哪一行。错误是。
这里
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 1 行说。 27 你使用了 AppCompatButton 但在初始化它时你使用了 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; 很可能应该有效。
我正在尝试做这个音乐播放器应用程序。
我在 2x2 网格布局中为每个位置创建了一个相对布局，在每个相对布局中，我放置了一个搜索栏和一个按钮。我想为每个按钮播放不同的音乐，按钮上方的搜索栏应该用于设置音乐位置。
此外，我使用标签来确定按下了哪个按钮。
完成界面后，我开始实现 onPress 方法，但它无法正常工作，而且我不确定如何指定播放特定音乐时将激活的搜索栏。 .. 到目前为止，这是我的代码，在第 27 行 ( ImageView counter = (ImageView) view; ) 中显示错误，当我单击任何按钮时崩溃：
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);
}
}
这里是 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>
错误日志：
FATAL EXCEPTION: main Process: com.victorpietro.musicproject, PID: 12799 java.lang.IllegalStateException: Could not execute method for android:onClick at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293) at android.view.View.performClick(View.java:6294) at android.view.View$PerformClick.run(View.java:24770) at android.os.Handler.handleCallback(Handler.java:790) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:6494) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) Caused by: 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) 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$MethodAndArgsCaller.run(RuntimeInit.java:438) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) Caused by: java.lang.ClassCastException: android.support.v7.widget.AppCompatButton cannot be cast to android.widget.ImageView at com.victorpietro.musicproject.MainActivity.onPress(MainActivity.java:27) at java.lang.reflect.Method.invoke(Native Method) at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) at android.view.View.performClick(View.java:6294) at android.view.View$PerformClick.run(View.java:24770) at android.os.Handler.handleCallback(Handler.java:790) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:6494) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
这里就可以了！根本不要触摸您的 xml 并在您应用的 java 代码端执行这些操作
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;
}
您的 logcat 清楚地说明了错误是什么。请浏览 logcat 并找出在哪一行。错误是。 这里
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 1 行说。 27 你使用了 AppCompatButton 但在初始化它时你使用了 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; 很可能应该有效。