Question

我发现这个问题很普遍，我搜索它，但没有回应我正在发生的事情。

以下是Log Cat：

05-10 19:42:31.564: E/AndroidRuntime(2839): FATAL EXCEPTION: main
05-10 19:42:31.564: E/AndroidRuntime(2839): Process: com.blabla.quiztest, PID: 2839
05-10 19:42:31.564: E/AndroidRuntime(2839): java.lang.IllegalStateException: **Could not find a method setupMessageButton(View) in the activity class com.blabla.quiztest.MainActivity for onClick handler on view class android.widget.Button with id 'button1'**
05-10 19:42:31.564: E/AndroidRuntime(2839):     at android.view.View$1.onClick(View.java:3810)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at android.view.View.performClick(View.java:4438)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at android.view.View$PerformClick.run(View.java:18422)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at android.os.Handler.handleCallback(Handler.java:733)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at android.os.Handler.dispatchMessage(Handler.java:95)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at android.os.Looper.loop(Looper.java:136)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at android.app.ActivityThread.main(ActivityThread.java:5017)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at java.lang.reflect.Method.invokeNative(Native Method)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at java.lang.reflect.Method.invoke(Method.java:515)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at dalvik.system.NativeStart.main(Native Method)
05-10 19:42:31.564: E/AndroidRuntime(2839): Caused by: java.lang.NoSuchMethodException: setupMessageButton [class android.view.View]
05-10 19:42:31.564: E/AndroidRuntime(2839):     at java.lang.Class.getConstructorOrMethod(Class.java:472)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at java.lang.Class.getMethod(Class.java:857)
05-10 19:42:31.564: E/AndroidRuntime(2839):     at android.view.View$1.onClick(View.java:3803)
05-10 19:42:31.564: E/AndroidRuntime(2839):     ... 11 more

MainActivity.xml

package com.blabla.quiztest;

import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity {

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

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment())
                .commit();
    }
}


public void setupMessageButton() {
  Button button = (Button) findViewById(R.id.button1);
  button.setOnClickListener(new View.OnClickListener() {
      public void onClick(View view) {
          // Do something in response to button click
          //Intent intent = new Intent(this, DisplayMessageActivity.class);
          Context context = getApplicationContext();
          CharSequence text = "Hello toast!";
          int duration = Toast.LENGTH_SHORT;

          Toast toast = Toast.makeText(context, text, duration);
          toast.show();
      }
  });
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        return rootView;
    }
}

}

在 fragment_main.xml

中

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:layout_marginBottom="189dp"
    android:onClick="setupMessageButton"
    android:text="Button" />

可能是什么问题？

Answer 1

2个解决方案：

把它放在你的oncreate：

Button button = (Button) findViewById(R.id.button1);
  button.setOnClickListener(new View.OnClickListener() {
      public void onClick(View view) {
          // Do something in response to button click
          //Intent intent = new Intent(this, DisplayMessageActivity.class);
          Context context = getApplicationContext();
          CharSequence text = "Hello toast!";
          int duration = Toast.LENGTH_SHORT;

          Toast toast = Toast.makeText(context, text, duration);
          toast.show();
      }

或者将所有setupmessagebutton（）替换为：

您还需要将setupmessagebutton（）更改为setupmessagebutton（查看视图）

Context context = getApplicationContext();
          CharSequence text = "Hello toast!";
          int duration = Toast.LENGTH_SHORT;

          Toast toast = Toast.makeText(context, text, duration);
          toast.show();

我会选择第二种解决方案，但这取决于你。

编辑：问题是您在XML中定义了一个onclick回调，您不需要在代码中设置OnClickListener。

Answer 2

当您使用onClick侦听器及其属性android:onClick="foo"时，该方法必须在其参数中使用已单击的View。如下：

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

正如您在the Documentation（第一部分）中所看到的那样：

您在android：onClick属性中声明的方法必须具有完全如上所示的签名。具体而言，该方法必须：
   - 公开发言    - 返回空白
   - 将视图定义为唯一参数（这将是单击的视图）

最后，您使用xml中的属性，然后您不需要在setOnClickListener中调用Activity方法，因为系统已使用此属性使用OnClickListener。<登记/> 然后，您的方法需要是：

public void setupMessageButton(View view) {
    // Do something in response to button click
    //Intent intent = new Intent(this, DisplayMessageActivity.class);
    Context context = getApplicationContext();
    CharSequence text = "Hello toast!";
    int duration = Toast.LENGTH_SHORT;

    Toast toast = Toast.makeText(context, text, duration);
    toast.show();
}

此外，如果您想要更新或使用点击事件中按下的View，请使用以下变量：

public void foo(View view) {
    // view = the view clicked.
    view.setText("Clicked");
}

Answer 3

该消息说它正在寻找这样的方法：

setupMessageButton(View)

你定义了这个：

public void setupMessageButton() {

您需要添加View参数：

public void setupMessageButton(View view) {

Answer 4

您需要关注LogCat中的这一行：

java.lang.IllegalStateException: **Could not find a method setupMessageButton(View) in the activity class com.blabla.quiztest.MainActivity for onClick handler on view class android.widget.Button with id 'button1'**

请注意：

Could not find a method setupMessageButton(View)...for onClick handler on view class

这是因为您在XML中使用了android:onClick="setupMessageButton"但未在类中为该操作创建相应的方法。

您创建了public void setupMessageButton()，但正如错误日志所述，它正在寻找View参数。

所以改变这个：

public void setupMessageButton() {

到此：

public void setupMessageButton(View view) {

该方法只需要View参数即可识别＆＃34;。

我按下按钮时出错

4 个答案: