无法在父级或祖先上下文中找到方法

Question

我一直在处理这个问题,并查看了我能找到的所有相关问题,例如:这一个,这一个,还有这一个.你能帮我纠正这个错误吗？它是logcat抛出的唯一一个.

java.lang.IllegalStateException: Could not find method playPauseMusic(View) in a parent or
ancestor Context for android:onClick attribute defined on view class
android.support.v7.widget.AppCompatImageButton with id 'playPause'

相关代码:

radio.java

package com.example.jacob.wutk;

import android.media.AudioManager;
import android.media.MediaPlayer;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageButton;

import java.io.IOException;

public class radio extends AppCompatActivity {

    /** Called when the user touches the button */

    public void playPauseMusic (View view, final ImageButton playPause) throws IOException {
        String url = "http://streamer.cci.utk.edu:8000/wutk-vorbis"; // your URL here
        final MediaPlayer mediaPlayer = new MediaPlayer();

        mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {

            public void onPrepared(MediaPlayer mediaPlayer){
                mediaPlayer.start();
            }
        });

        playPause.setOnClickListener(new View.OnClickListener(){
            public void onClick(View view) {
                if (mediaPlayer.isPlaying()) {
                    mediaPlayer.pause();
                    playPause.setImageResource(R.drawable.play1);
                } else {
                    playPause.setImageResource(R.drawable.pause1);
                }
            }
        });
        mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
        mediaPlayer.setDataSource(url);
        mediaPlayer.prepareAsync();
    }

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

activity_radio.xml

    <?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    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:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    tools:context="com.example.jacob.wutk.radio">
    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="left|center_vertical"
        android:scaleType="centerCrop"
        android:src="@drawable/background_mic1"/>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:paddingBottom="1.0dip"
        android:paddingLeft="4.0dip"
        android:paddingRight="4.0dip"
        android:paddingTop="5.0dip">
       <ImageButton
           android:id="@+id/playPause"
           android:layout_width="0.0dip"
           android:layout_height="wrap_content"
           android:layout_weight="1.0"
           android:background="?android:selectableItemBackground"
           android:clickable="true"
           android:onClick="playPauseMusic"
           android:scaleType="fitCenter"
           android:src="@drawable/play1"/>
       <ImageView
           android:layout_width="0.0dip"
           android:layout_height="fill_parent"
           android:layout_marginRight="5dp"
           android:layout_weight="1.0"
           android:background="?android:selectableItemBackground"
           android:scaleType="fitCenter"
           android:src="@drawable/logo"/>

    </LinearLayout>

</FrameLayout>

Answer 1

定义onClick中xml意味着你需要将它定义为这里特定的观点是ImageButton,你不能在该方法两个参数.

你的错误也说无法找到方法playPauseMusic(View)意味着编译器需要一个带有单个参数的方法View,因为你有两个参数View,ImageButton这就是你得到那个错误的原因.只需从方法中删除一个参数即可.

像这样做 :

public class radio extends AppCompatActivity {

/** Called when the user touches the button */

public void playPauseMusic (View playPause) {
    String url = "http://streamer.cci.utk.edu:8000/wutk-vorbis"; // your URL here
    final MediaPlayer mediaPlayer = new MediaPlayer();

    mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {

        public void onPrepared(MediaPlayer mediaPlayer){
            mediaPlayer.start();
        }
    });


    if (mediaPlayer.isPlaying()) {
         mediaPlayer.pause();
         ((ImageButton)playPause).setImageResource(R.drawable.play1);
    } else {
        ((ImageButton)playPause).setImageResource(R.drawable.pause1);
    }

    mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
    mediaPlayer.setDataSource(url);
    mediaPlayer.prepareAsync();
}

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

写入的另一件事android:onClick="playPauseMusic"意味着该方法playPauseMusic将在Button上调用,因此您已经定义了一个按钮单击,因此无需在方法中定义它,playPause.setOnClickListener因此我删除了该代码.

Answer 2

您的代码可能应该从以下开始:

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

你在xml中指定onClick

android:onClick="playPauseMusic"

所以,该方法有效,你也有内在的onClicks.如果他们是一些观点.

你必须初始化并从代码中的xml中获取它,因为ex-

如果你有xml中的ImageButton,其id为"playPause"

ImageButton playPause; //Declare it here if you wanna use it in all other places in the class or outside of your class

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

    playPause = (ImageButton)findViewById(R.id.playPause);

    playPause.setOnClickListener(new View.OnClickListener(){
        public void onClick(View view) {
           //OnCLick Stuff
        }
    });
}

在您的情况下,您在xml中有onClick属性,在代码中有另一个onCLick.你用一个.