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Java 无法识别空指针异常_Java_Android - Fatal编程技术网

Java 无法识别空指针异常

Java 无法识别空指针异常,java,android,Java,Android,好吧,我已经试了好几个小时了,但我找不到解决办法。 下面是log cat所说的空指针期望值的代码: import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.Button; public class splash extends Activity{ Button begin; @Over

好吧,我已经试了好几个小时了,但我找不到解决办法。 下面是log cat所说的空指针期望值的代码:

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

public class splash extends Activity{
Button begin;
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    begin=(Button) findViewById(R.id.button);
    begin.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            // TODO Auto-generated method stub
            Intent startmenu=new Intent("com.life.project.menu");
            startActivity(startmenu);
        }
    });
}

}
下面是xml文件:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" android:background="@drawable/icon3">

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="You have 20 minutes to increase your status as much as possible." />

<Button
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Begin!"
    android:layout_gravity="center"
    android:typeface="monospace" />

 </LinearLayout>


因此,当我尝试运行它时,它会出现一个空指针异常,我不知道它有什么问题,有什么想法吗?

您需要在
findViewById
之前调用
setContentView

setContentView(R.layout.the_layout_xml_name);
begin=(Button) findViewById(R.id.button);
// ...

您需要在
findViewById
之前调用
setContentView

setContentView(R.layout.the_layout_xml_name);
begin=(Button) findViewById(R.id.button);
// ...

空指针发生在哪一行?请发布异常的堆栈跟踪。空指针发生在哪一行?请发布异常的堆栈跟踪。