Question

I am reading Hello Android book and I am writing the code from the book in eclipse but the buttons not working. Why is that?

Sudoku/src/org.example.sudoku/Sudoku.java

package org.example.sudoku;

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

public class Sudoku extends Activity implements OnClickListener {
private static final String TAG = "Sudoku";

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

    // Set up click listeners for all the buttons
    View continueButton = findViewById(R.id.continue_button);
    continueButton.setOnClickListener(this);
    View newButton = findViewById(R.id.new_button);
    newButton.setOnClickListener(this);
    View aboutButton = findViewById(R.id.about_button);
    aboutButton.setOnClickListener(this);
    View exitButton = findViewById(R.id.exit_button);
    exitButton.setOnClickListener(this);
 }



 // ...
 public void onClick(View v) {
     switch (v.getId()) {
     case R.id.about_button:
         Intent i = new Intent(this, About.class);
         startActivity(i);
         break;
     // More buttons go here (if any) ...

     }
  }
}

Sudoku/src/org.example.sudoku/About.java

package org.example.sudoku;

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

public class About extends Activity{
@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.about);
}
 }

AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.example.sudoku"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="15" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
             android:name=".MainActivity"
             android:label="@string/title_activity_main" >
             <intent-filter>
                  <action android:name="android.intent.action.MAIN" />

                  <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
        </activity>
        <activity android:name=".About"
            android:label="@string/about_label">     
        </activity>            

    </application>

 </manifest>

I click in About button, but not working and not run activity. if you need another files of program, tell me.
Please help me.
Thank you.

Answer 1

Try this. In Manifest file you write MainActivity please change it to Sudoku.

For this error cannot convert from View to Button

You need to cast the view to Button:

Button aboutButton  = (Button)findViewById(android.R.id.aboutButton );