java - 我使用多个 OnClickListeners 得到致命异常

Question

主要的事情发生在致命执行中，我的应用程序没有启动，不幸的是错误停止了，它一直在崩溃尝试切换案例，否则如果错误仍然存​​在，应用程序会不断崩溃在 stackflow 上搜索并搜索不同的 usersover stackflowed 遇到了这个错误，即使在尝试使用单个 if 和单个 onclicklistener 应用程序设法运行但不是多个 onlicklistener 的解决方案后，错误仍然存​​在我仍然存在是否有不同的方式来运行多个 onclick 监听器应用程序请帮帮我

这里是 MainActivity.java

package com.example.cricscore;

import android.app.Activity; 
import android.os.Bundle; 
import android.util.Log;
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.TextView; 

public class MainActivity extends Activity { 

// Private member field to keep track of the count 
private int mCount = 0; 
private static final String TAG = "MainActivity"; 


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


    Button buttonA = (Button) findViewById(R.id.button1);    
    buttonA.setOnClickListener((OnClickListener) this);
    Button buttonB = (Button) findViewById(R.id.button2); 
    buttonB.setOnClickListener((OnClickListener) this);
 }

   public void onClick(View v) {
       try {
        switch (v.getId()) {
           case R.id.button1: 
               mCount++; 
               final TextView countTextView = (TextView) findViewById(R.id.textView1);
               countTextView.setText(""+ mCount); 
            break;
           case R.id.button2:
               mCount= mCount+2 ; 
               final TextView countTextView1 = (TextView) findViewById(R.id.textView1);
               countTextView1.setText(""+ mCount);
            break;


        }
       }
       catch(Throwable t) {
           Log.e(TAG, t.getMessage(), t);

       }

   }
 }

Activity_main.xml 是

<RelativeLayout 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"
tools:context=".MainActivity" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:textAppearance="?android:attr/textAppearanceLarge" />

<TextView
    android:id="@+id/textView3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignRight="@+id/button2"
    android:layout_below="@+id/textView1"
    android:text="Runs" />

<TextView
    android:id="@+id/textView4"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/textView3"
    android:layout_alignBottom="@+id/textView3"
    android:layout_alignRight="@+id/textView2"
    android:layout_marginRight="19dp"
    android:text="Wickets" />

<TextView
    android:id="@+id/textView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/textView4"
    android:layout_alignParentRight="true"
    android:text="Large Text"
    android:textAppearance="?android:attr/textAppearanceLarge" />

<Button
    android:id="@+id/button1"
    style="?android:attr/buttonStyleSmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_below="@+id/textView3"
    android:text="1" />

<Button
    android:id="@+id/button2"
    style="?android:attr/buttonStyleSmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/button1"
    android:layout_alignBottom="@+id/button1"
    android:layout_toRightOf="@+id/button1"
    android:text="2" />

<Button
    android:id="@+id/button4"
    style="?android:attr/buttonStyleSmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_below="@+id/button1"
    android:text="6" />

<Button
    android:id="@+id/button6"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/button5"
    android:layout_alignRight="@+id/textView4"
    android:text="Wicket" />

<Button
    android:id="@+id/button7"
    style="?android:attr/buttonStyleSmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/button8"
    android:layout_alignBottom="@+id/button8"
    android:layout_alignLeft="@+id/button5"
    android:text="Balls" />

<Button
    android:id="@+id/button3"
    style="?android:attr/buttonStyleSmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/textView3"
    android:layout_toRightOf="@+id/button7"
    android:text="4" />

<Button
    android:id="@+id/button8"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_marginBottom="44dp"
    android:layout_toLeftOf="@+id/textView2"
    android:text="Button" />

<Button
    android:id="@+id/button5"
    style="?android:attr/buttonStyleSmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/button4"
    android:layout_alignBottom="@+id/button4"
    android:layout_toLeftOf="@+id/textView7"
    android:text="No/Wide" />

<TextView
    android:id="@+id/textView6"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/textView7"
    android:layout_alignBottom="@+id/textView7"
    android:layout_alignRight="@+id/button5"
    android:text="Large Text"
    android:textAppearance="?android:attr/textAppearanceLarge" />

<TextView
    android:id="@+id/textView7"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/button8"
    android:layout_toLeftOf="@+id/textView4"
    android:text="Large Text"
    android:textAppearance="?android:attr/textAppearanceLarge" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

</RelativeLayout>

日志

03-18 14:09:37.717: E/AndroidRuntime(360): FATAL EXCEPTION: main
03-18 14:09:37.717: E/AndroidRuntime(360): java.lang.RuntimeException: Unable to start      
    activity
  ComponentInfo{com.example.abc/com.example.abc.MainActivity}:  java.lang.ClassCastException:    
  com.example.abc.MainActivity
  03-18 14:09:37.717: E/AndroidRuntime(360):    at     
  android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at   
  android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:1663)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at android.app.ActivityThread.access$1500
  (ActivityThread.java:117)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at android.app.ActivityThread$H.handleMessage 
  (ActivityThread.java:931)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at android.os.Handler.dispatchMessage 
  (Handler.java:99)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at android.os.Looper.loop(Looper.java:123)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at android.app.ActivityThread.main 
  (ActivityThread.java:3683)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at java.lang.reflect.Method.invokeNative(Native  
  Method)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at java.lang.reflect.Method.invoke 
  (Method.java:507)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at  
  com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at com.android.internal.os.ZygoteInit.main 
  (ZygoteInit.java:597)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at dalvik.system.NativeStart.main(Native Method)
  03-18 14:09:37.717: E/AndroidRuntime(360): Caused by: java.lang.ClassCastException:  
  com.example.abc.MainActivity
  03-18 14:09:37.717: E/AndroidRuntime(360):    at com.example.abc.MainActivity.onCreate 
  (MainActivity.java:30)
  03-18 14:09:37.717: E/AndroidRuntime(360):    at   
  android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
   03-18 14:09:37.717: E/AndroidRuntime(360):   at  
   android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
   03-18 14:09:37.717: E/AndroidRuntime(360):   ... 11 more

经过一些修改正如第一个答案所说，我的代码没有崩溃，但我只能看到 android_mainfest 仍然相同的空白 Activity

package com.example.cricscore;

import android.app.Activity; 
import android.os.Bundle; 
import android.util.Log;
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.TextView; 

public class MainActivity extends Activity implements OnClickListener { 

// Private member field to keep track of the count 
private int mCount = 0; 
/** Called when the activity is first created. 
 * @param OnClickListener */
public void onCreate(Bundle savedInstanceState, android.view.View.OnClickListener 
OnClickListener){
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 


    Button buttonA = (Button) findViewById(R.id.button1);    
    buttonA.setOnClickListener((OnClickListener) );
    Button buttonB = (Button) findViewById(R.id.button2); 
    buttonB.setOnClickListener((OnClickListener) );
 }

   public void OnClickListener(View v) {

        switch (v.getId()) {
           case R.id.button1: 
               mCount++; 
               final TextView countTextView = (TextView) findViewById(R.id.textView1);
               countTextView.setText(""+ mCount); 
            break;
           case R.id.button2:
               mCount= mCount+2 ; 
               final TextView countTextView1 = (TextView) findViewById(R.id.textView1);
               countTextView1.setText(""+ mCount);
            break;


        }


   }

@Override
public void onClick(View v) {
    // TODO Auto-generated method stub

}
 }

Answer 1

setOnClickListener方法需要一个类型为 View.OnClickListener 的参数.你正在做的是服用 Activity本身，并试图强制它成为 OnClickListener，但在这段代码中它不是:

Button buttonA = (Button) findViewById(R.id.button1);    
buttonA.setOnClickListener((OnClickListener) this); // <-- here
Button buttonB = (Button) findViewById(R.id.button2); 
buttonB.setOnClickListener((OnClickListener) this); // <-- and here too

您应该将您的 Activity 声明为 OnClickListener，使用:

public class MainActivity extends Activity implements OnClickListener

并且因为您已经有了 onClick(View v) 方法，所以应该解决问题。