Question

myButton.setOnClickListener(new MyButtonListerer());错误 在线等！！！

/**
显示空指针异常

*/
package wang.activit_02;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.os.Build;

public class MainActivity extends ActionBarActivity {
private Button myButton=null;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myButton = (Button)findViewById(R.id.myButton);

myButton.setOnClickListener(new MyButtonListerer());

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

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent = new Intent();
intent.setClass(MainActivity.this, OtherActivity.class);
MainActivity.this.startActivity(intent);
System.out.println(123);
}

}

Answer 1

我猜的原因可能是
myButton对象的onClickListener属性在数据库或者其他地方有限制，默认不能为空，而
new MyButtonListerer()这是一个空对象，所以就报空指针了