刚开始学,按照第一行代码中给出的例子写的,结果出现空指针报错,自己试了好久也没改出来,求大神庇佑
~~~~附上代码
package com.sample.test02;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.Toast;
public class FirstB extends Activity{
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_CONTEXT_MENU);
setContentView(com.sample.test02.R.layout.first_layout);
Button butt=(Button)findViewById(com.sample.test02.R.id.button_1);
butt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(FirstB.this,"@+string/bt",Toast.LENGTH_SHORT).show();
}
});
}
}
logcat error报错
10-05 11:45:06.951: E/AndroidRuntime(17114): FATAL EXCEPTION: main
10-05 11:45:06.951: E/AndroidRuntime(17114): Process: com.sample.test02, PID: 17114
10-05 11:45:06.951: E/AndroidRuntime(17114): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sample.test02/com.sample.test02.FirstB}: java.lang.NullPointerException
10-05 11:45:06.951: E/AndroidRuntime(17114): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2372)
10-05 11:45:06.951: E/AndroidRuntime(17114): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2424)
10-05 11:45:06.951: E/AndroidRuntime(17114): at android.app.ActivityThread.access$800(ActivityThread.java:154)
10-05 11:45:06.951: E/AndroidRuntime(17114): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1347)
10-05 11:45:06.951: E/AndroidRuntime(17114): at android.os.Handler.dispatchMessage(Handler.java:110)
10-05 11:45:06.951: E/AndroidRuntime(17114): at android.os.Looper.loop(Looper.java:193)
10-05 11:45:06.951: E/AndroidRuntime(17114): at android.app.ActivityThread.main(ActivityThread.java:5339)
10-05 11:45:06.951: E/AndroidRuntime(17114): at java.lang.reflect.Method.invokeNative(Native Method)
10-05 11:45:06.951: E/AndroidRuntime(17114): at java.lang.reflect.Method.invoke(Method.java:515)
10-05 11:45:06.951: E/AndroidRuntime(17114): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:835)
10-05 11:45:06.951: E/AndroidRuntime(17114): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:651)
10-05 11:45:06.951: E/AndroidRuntime(17114): at dalvik.system.NativeStart.main(Native Method)
10-05 11:45:06.951: E/AndroidRuntime(17114): Caused by: java.lang.NullPointerException
10-05 11:45:06.951: E/AndroidRuntime(17114): at com.sample.test02.FirstB.onCreate(FirstB.java:16)
10-05 11:45:06.951: E/AndroidRuntime(17114): at android.app.Activity.performCreate(Activity.java:5360)
10-05 11:45:06.951: E/AndroidRuntime(17114): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
10-05 11:45:06.951: E/AndroidRuntime(17114): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2336)
10-05 11:45:06.951: E/AndroidRuntime(17114): ... 11 more
刚开始写android代码,不是很看得懂logcat给的报错