android - "Could not find a method .. in the activity class .. for onClick handler"

Question

我正在开发我的第一个 android 项目。我正在使用 thinkgear api。我有两个 Activity 。我有一个 Intent 在第一个 Activity 中调用以开始第二个 Activity 。在我的第二个 Activity 中，我有一个播放声音的按钮和一个暂停声音的按钮。但是当我尝试在第二个 Activity 中播放声音时，我的应用程序结束了。请指出错误。我附上了 java 文件和 logcat 文件。

mindwave1.java

package com.example.mindwave1;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
//import android.util.Log;
//import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import com.neurosky.thinkgear.*;

public class MainActivity extends Activity {
BluetoothAdapter bluetoothAdapter;

TextView tv;
Button b;

TGDevice tgDevice;
final boolean rawEnabled = true;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tv = (TextView)findViewById(R.id.textView1);
    tv.setText("");
    tv.append("Android version: " + Integer.valueOf(android.os.Build.VERSION.SDK_INT) +      "\n" );
    bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    if(bluetoothAdapter == null) {
        // Alert user that Bluetooth is not available
        Toast.makeText(this, "Bluetooth not available", Toast.LENGTH_LONG).show();
        finish();
        return;
    }else {
        /* create the TGDevice */
        tgDevice = new TGDevice(bluetoothAdapter, handler);
    }  
}

@Override
public void onDestroy() {
    tgDevice.close();
    super.onDestroy();
}
/**
 * Handles messages from TGDevice
 */
@SuppressLint("HandlerLeak")
private final Handler handler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
        case TGDevice.MSG_STATE_CHANGE:

            switch (msg.arg1) {
                case TGDevice.STATE_IDLE:
                    break;
                case TGDevice.STATE_CONNECTING:                         
                    tv.append("Connecting...\n");
                    break;                          
                case TGDevice.STATE_CONNECTED:
                    tv.append("Connected.\n");
                    tgDevice.start();
                    break;
                case TGDevice.STATE_NOT_FOUND:
                    tv.append("Can't find\n");
                    break;
                case TGDevice.STATE_NOT_PAIRED:
                    tv.append("not paired\n");
                    break;
                case TGDevice.STATE_DISCONNECTED:
                    tv.append("Disconnected mang\n");
            }

            break;
        //case TGDevice.MSG_POOR_SIGNAL:
                //signal = msg.arg1;
                //tv.append("PoorSignal: " + msg.arg1 + "\n");
            //break;
        case TGDevice.MSG_RAW_DATA:   
                //raw1 = msg.arg1;
                //tv.append("Got raw: " + msg.arg1 + "\n");
            break;
        case TGDevice.MSG_HEART_RATE:
            tv.append("Heart rate: " + msg.arg1 + "\n");
            break;
        case TGDevice.MSG_ATTENTION:
                //att = msg.arg1;
                tv.setText("");
                tv.append("Test number 1 for attention and meditation\n");
                tv.append("Attention: " + msg.arg1 + "\n");
                //Log.v("HelloA", "Attention: " + msg.arg1 + "\n");
            break;
        case TGDevice.MSG_MEDITATION:
                tv.append("Meditation: " + msg.arg1 +"\n");
            break;
        case TGDevice.MSG_BLINK:
                tv.append("Blink: " + msg.arg1 + "\n");
            break;
        case TGDevice.MSG_RAW_COUNT:
                //tv.append("Raw Count: " + msg.arg1 + "\n");
            break;
        case TGDevice.MSG_LOW_BATTERY:
            Toast.makeText(getApplicationContext(), "Low battery!", Toast.LENGTH_SHORT).show();
            break;
        case TGDevice.MSG_RAW_MULTI:
            //TGRawMulti rawM = (TGRawMulti)msg.obj;
            //tv.append("Raw1: " + rawM.ch1 + "\nRaw2: " + rawM.ch2);
        default:
            break;
    }
    }
};

public void nxt(View view)
{
    Intent intent = new Intent(this, SecondPageActivity.class);
    startActivity(intent);
}

public void doStuff(View view) {
    if(tgDevice.getState() != TGDevice.STATE_CONNECTING && tgDevice.getState() != TGDevice.STATE_CONNECTED)
        tgDevice.connect(rawEnabled);   
    //tgDevice.ena
}
}

SecondPageActivity.java

package com.example.mindwave1;

import android.os.Bundle;
import android.media.MediaPlayer;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.support.v4.app.NavUtils;

public class SecondPageActivity extends Activity {

MediaPlayer mp;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second_page);
    // Show the Up button in the action bar.
    setupActionBar();
}



public void play(){

    mp = MediaPlayer.create(SecondPageActivity.this, R.raw.music);
    mp.start();
}

/**
 * Set up the {@link android.app.ActionBar}.
 */
private void setupActionBar() {

    getActionBar().setDisplayHomeAsUpEnabled(true);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.second_page, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case android.R.id.home:
        // This ID represents the Home or Up button. In the case of this
        // activity, the Up button is shown. Use NavUtils to allow users
        // to navigate up one level in the application structure. For
        // more details, see the Navigation pattern on Android Design:
        //

        //
        NavUtils.navigateUpFromSameTask(this);
        return true;
    }
    return super.onOptionsItemSelected(item);
}

}

日志文件

04-16 16:29:50.676: D/dalvikvm(13458): GC_FOR_ALLOC freed 65K, 2% free 7676K/7784K, paused 22ms, total 22ms
04-16 16:29:50.676: I/dalvikvm-heap(13458): Grow heap (frag case) to 8.899MB for 1436984-byte allocation
04-16 16:29:50.716: D/dalvikvm(13458): GC_FOR_ALLOC freed 1K, 2% free 9078K/9188K, paused 37ms, total 37ms
04-16 16:29:50.746: V/TGDevice(13458): EKG path: /storage/emulated/0/Android/data/com.neurosky.thinkgear/files/EKG/parameters
04-16 16:29:50.746: D/TGDevice(13458): Initialized. Version: 9
04-16 16:29:50.806: D/libEGL(13458): loaded /system/lib/egl/libEGL_tegra.so
04-16 16:29:50.826: D/libEGL(13458): loaded /system/lib/egl/libGLESv1_CM_tegra.so
04-16 16:29:50.846: D/libEGL(13458): loaded /system/lib/egl/libGLESv2_tegra.so
04-16 16:29:50.866: D/OpenGLRenderer(13458): Enabling debug mode 0
04-16 16:29:57.736: V/mindwave1(13458): appln2 start
04-16 16:30:06.076: D/AndroidRuntime(13458): Shutting down VM
04-16 16:30:06.076: W/dalvikvm(13458): threadid=1: thread exiting with uncaught exception (group=0x41834ba8)
04-16 16:30:06.076: E/AndroidRuntime(13458): FATAL EXCEPTION: main
04-16 16:30:06.076: E/AndroidRuntime(13458): Process: com.example.mindwave1, PID: 13458
04-16 16:30:06.076: E/AndroidRuntime(13458): java.lang.IllegalStateException: Could not find a method play(View) in the activity class com.example.mindwave1.SecondPageActivity for onClick handler on view class android.widget.Button with id 'button1'
04-16 16:30:06.076: E/AndroidRuntime(13458):    at android.view.View$1.onClick(View.java:3810)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at android.view.View.performClick(View.java:4438)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at android.view.View$PerformClick.run(View.java:18422)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at android.os.Handler.handleCallback(Handler.java:733)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at android.os.Handler.dispatchMessage(Handler.java:95)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at android.os.Looper.loop(Looper.java:136)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at android.app.ActivityThread.main(ActivityThread.java:5017)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at java.lang.reflect.Method.invokeNative(Native Method)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at java.lang.reflect.Method.invoke(Method.java:515)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at dalvik.system.NativeStart.main(Native Method)
04-16 16:30:06.076: E/AndroidRuntime(13458): Caused by: java.lang.NoSuchMethodException: play [class android.view.View]
04-16 16:30:06.076: E/AndroidRuntime(13458):    at java.lang.Class.getConstructorOrMethod(Class.java:472)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at java.lang.Class.getMethod(Class.java:857)
04-16 16:30:06.076: E/AndroidRuntime(13458):    at android.view.View$1.onClick(View.java:3803)
04-16 16:30:06.076: E/AndroidRuntime(13458):    ... 11 more
04-16 16:35:06.416: D/dalvikvm(13736): GC_FOR_ALLOC freed 69K, 2% free 7676K/7788K, paused 24ms, total 24ms
04-16 16:35:06.416: I/dalvikvm-heap(13736): Grow heap (frag case) to 8.900MB for 1436984-byte allocation
04-16 16:35:06.446: D/dalvikvm(13736): GC_FOR_ALLOC freed 1K, 2% free 9078K/9192K, paused 25ms, total 25ms
04-16 16:35:06.466: V/TGDevice(13736): EKG path: /storage/emulated/0/Android/data/com.neurosky.thinkgear/files/EKG/parameters
04-16 16:35:06.466: D/TGDevice(13736): Initialized. Version: 9
04-16 16:35:06.516: D/libEGL(13736): loaded /system/lib/egl/libEGL_tegra.so
04-16 16:35:06.536: D/libEGL(13736): loaded /system/lib/egl/libGLESv1_CM_tegra.so
04-16 16:35:06.546: D/libEGL(13736): loaded /system/lib/egl/libGLESv2_tegra.so
04-16 16:35:06.566: D/OpenGLRenderer(13736): Enabling debug mode 0
04-16 16:39:46.226: D/dalvikvm(13927): GC_FOR_ALLOC freed 73K, 2% free 7676K/7788K, paused 20ms, total 21ms
04-16 16:39:46.236: I/dalvikvm-heap(13927): Grow heap (frag case) to 8.899MB for 1436984-byte allocation
04-16 16:39:46.256: D/dalvikvm(13927): GC_FOR_ALLOC freed 1K, 2% free 9078K/9192K, paused 22ms, total 22ms
04-16 16:39:46.296: V/TGDevice(13927): EKG path: /storage/emulated/0/Android/data/com.neurosky.thinkgear/files/EKG/parameters
04-16 16:39:46.296: D/TGDevice(13927): Initialized. Version: 9
04-16 16:39:46.366: D/libEGL(13927): loaded /system/lib/egl/libEGL_tegra.so
04-16 16:39:46.376: D/libEGL(13927): loaded /system/lib/egl/libGLESv1_CM_tegra.so
04-16 16:39:46.396: D/libEGL(13927): loaded /system/lib/egl/libGLESv2_tegra.so
04-16 16:39:46.416: D/OpenGLRenderer(13927): Enabling debug mode 0
04-16 16:39:50.416: V/mindwave1(13927): appln2 start
04-16 16:39:51.666: D/AndroidRuntime(13927): Shutting down VM
04-16 16:39:51.666: W/dalvikvm(13927): threadid=1: thread exiting with uncaught exception (group=0x41834ba8)
04-16 16:39:51.676: E/AndroidRuntime(13927): FATAL EXCEPTION: main
04-16 16:39:51.676: E/AndroidRuntime(13927): Process: com.example.mindwave1, PID: 13927
04-16 16:39:51.676: E/AndroidRuntime(13927): java.lang.IllegalStateException: Could not find a method play(View) in the activity class com.example.mindwave1.SecondPageActivity for onClick handler on view class android.widget.Button with id 'button1'
04-16 16:39:51.676: E/AndroidRuntime(13927):    at android.view.View$1.onClick(View.java:3810)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at android.view.View.performClick(View.java:4438)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at android.view.View$PerformClick.run(View.java:18422)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at android.os.Handler.handleCallback(Handler.java:733)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at android.os.Handler.dispatchMessage(Handler.java:95)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at android.os.Looper.loop(Looper.java:136)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at android.app.ActivityThread.main(ActivityThread.java:5017)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at java.lang.reflect.Method.invokeNative(Native Method)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at java.lang.reflect.Method.invoke(Method.java:515)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at dalvik.system.NativeStart.main(Native Method)
04-16 16:39:51.676: E/AndroidRuntime(13927): Caused by: java.lang.NoSuchMethodException: play [class android.view.View]
04-16 16:39:51.676: E/AndroidRuntime(13927):    at java.lang.Class.getConstructorOrMethod(Class.java:472)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at java.lang.Class.getMethod(Class.java:857)
04-16 16:39:51.676: E/AndroidRuntime(13927):    at android.view.View$1.onClick(View.java:3803)
04-16 16:39:51.676: E/AndroidRuntime(13927):    ... 11 more

Answer 1

参见 Documentation ，在此示例中，sendMessage 方法使用:

a View as its only parameter (this will be the View that was clicked).

你的错误:

Could not find a method play(View) in the activity class com.example.mindwave1.SecondPageActivity for onClick handler on view class android.widget.Button with id 'button1'  

您需要在您的方法中使用View 参数。解决方案:

public void play(View view){
    ...
}