Question

我正在为一个班级制作一个Android应用程序，到目前为止我已经开始了，但是一旦应用程序启动，你点击屏幕，它就会在按钮不可见时做任何事情，或者当按钮可见时，它会崩溃应用程序。它应该转移到一个新的活动。（登录）

错误就是这个

02-25 18:02:54.250: E/AndroidRuntime(25252): FATAL EXCEPTION: main
02-25 18:02:54.250: E/AndroidRuntime(25252): java.lang.IllegalStateException: Could not find a method onClick (View v)(View) in the activity class jr.crfbla.etn.main for onClick handler on view class android.widget.Button with id 'button1'
02-25 18:02:54.250: E/AndroidRuntime(25252):    at android.view.View$1.onClick(View.java:3839)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at android.view.View.performClick(View.java:4489)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at android.view.View$PerformClick.run(View.java:18803)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at android.os.Handler.handleCallback(Handler.java:730)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at android.os.Handler.dispatchMessage(Handler.java:92)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at android.os.Looper.loop(Looper.java:137)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at android.app.ActivityThread.main(ActivityThread.java:5455)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at java.lang.reflect.Method.invokeNative(Native Method)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at java.lang.reflect.Method.invoke(Method.java:525)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1187)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at dalvik.system.NativeStart.main(Native Method)
02-25 18:02:54.250: E/AndroidRuntime(25252): Caused by: java.lang.NoSuchMethodException: onClick (View v) [class android.view.View]
02-25 18:02:54.250: E/AndroidRuntime(25252):    at java.lang.Class.getConstructorOrMethod(Class.java:423)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at java.lang.Class.getMethod(Class.java:787)
02-25 18:02:54.250: E/AndroidRuntime(25252):    at android.view.View$1.onClick(View.java:3832)

对纳什维尔清单的探索

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="jr.crfbla.etn"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="19" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:screenOrientation="landscape"
        android:theme="@style/NoActionBar" >


        <activity 
            android:name="main"
            android:label="@string/app_name"
            android:theme="@style/NoActionBar"
            android:screenOrientation="landscape"
            >
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>

        <activity
           android:name="login"
           android:label="@string/app_name"
           android:screenOrientation="landscape"
           android:theme="@style/NoActionBar"
           android:parentActivityName="main" >
           <meta-data
               android:name="android.support.PARENT_ACTIVITY"
               android:value="main" />         
         </activity>

    </application>

</manifest>

Home.xml

<?xml version="1.0" encoding="utf-8"?>
<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"
    android:layout_gravity="bottom"
    android:background="@drawable/home_page"
    android:configChanges="keyboardHidden|orientation|screenSize"
    android:screenOrientation="landscape"
    tools:context=".main" >

    <Button
        android:id="@+id/button1"
        style="?android:attr/buttonStyleSmall"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:focusableInTouchMode="true"
        android:longClickable="false"
        android:onClick="onClick (View v)"
        android:paddingLeft="96dp"
        android:text="@+string/Blank"
        android:visibility="invisible" />

</RelativeLayout>

main.java

package jr.crfbla.etn;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;

public class main extends Activity {
    public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
    /** Called when the activity is first created/ */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.home);
    }


/** Called when the user clicks the Start button */ 

    // Do something in response to button
      public void onClick (View button1) {
        Intent loginintent = new Intent(main.this, login.class);
            main.this.startActivity(loginintent);
            } 

}

login.xml

<?xml version="1.0" encoding="utf-8"?>
<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"
    android:background="@drawable/log_in_page"
    android:configChanges="keyboardHidden|orientation|screenSize"
    android:screenOrientation="landscape"
    tools:context="login" >

</RelativeLayout>

login.java
package jr.crfbla.etn;

import android.app.Activity;
import android.os.Bundle;

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

Answer 1

替换

android:onClick="onClick (View v)"

带

android:onClick="onClick"

Answer 2

您的Activity类应该实现View.OnClickListener接口，然后覆盖相应的onClick方法。正如其他人所指出的那样，布局XML中的onClick声明也是错误的，它必须读取“onClick”以匹配被覆盖的onClick方法。

Answer 3

请尝试以下说明：

//inside your layout file
<Button 
    android:id="@+id/mButton"
    android:text="Start"
    android:background="#ffffff" />

现在，在你的活动中试试这个：

public class MyActivity extends Activity implements View.OnClickListener{

   Button mButton;

   @Override
   public void onCreate(Bundle savedInstanceState){
      super.onCreate(savedInstanceState);

      setContentView(R.layout.main.xml);

      mButton = (Button)findViewById(R.id.mButton);

      mButton.setOnClickListener(this);
   }

   @Override
   public void onClick(View v){
      switch(v.getId()){
         case R.id.mButton:

              Intent intent = new Intent(this, SecondActivity.class);
              startActivity(intent);
              break;
        default:
             //nothing happened 
      }
   }
}

这种处理点击事件的方式确保您可以编写最小行，因为您只需要设置OnClickListener - 每个按钮一行，并使用switch语句检查单击了哪个按钮。如果你有更多的活动，你可以定义一个intent然后在每个按钮内实例化它们，具体取决于点击了哪个按钮

祝你好运！

Answer 4

您也不需要使用很长的方式来调用活动，尤其是在活动中调用它时。只需使用

startActivity(loginintent);

按钮上未启动的新活动单击[Android]

4 个答案: