Java android中的致命错误异常

我正在尝试编写android饮食计划器。调试后，我发现当我的第一页淡出，活动想转到第二页时，出现致命错误异常，但我找不到问题出在哪里？有人能帮我吗

错误

10-24 06:35:46.622: E/AndroidRuntime(1102): FATAL EXCEPTION: main
10-24 06:35:46.622: E/AndroidRuntime(1102): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.dietplanneraplication/com.example.dietplanneraplication.FeatureList}: java.lang.NullPointerException
10-24 06:35:46.622: E/AndroidRuntime(1102):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at android.app.ActivityThread.access$600(ActivityThread.java:130)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at android.os.Handler.dispatchMessage(Handler.java:99)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at android.os.Looper.loop(Looper.java:137)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at android.app.ActivityThread.main(ActivityThread.java:4745)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at java.lang.reflect.Method.invokeNative(Native Method)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at java.lang.reflect.Method.invoke(Method.java:511)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at dalvik.system.NativeStart.main(Native Method)
10-24 06:35:46.622: E/AndroidRuntime(1102): Caused by: java.lang.NullPointerException
10-24 06:35:46.622: E/AndroidRuntime(1102):     at com.example.dietplanneraplication.FeatureList.onCreate(FeatureList.java:26)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at android.app.Activity.performCreate(Activity.java:5008)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
10-24 06:35:46.622: E/AndroidRuntime(1102):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
10-24 06:35:46.622: E/AndroidRuntime(1102):     ... 11 more

XML代码

MAINACTIVITY.XML

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:id="@+id/firstpage"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:background="#eee"
 android:orientation="vertical" >
 <LinearLayout
    android:id="@+id/logoid"
    android:layout_width="200dip"
    android:layout_height="200dip"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:background="@drawable/logo_shadow4"
    android:orientation="vertical" >

 </LinearLayout>
</RelativeLayout>

FEATURELIST.JAVa

package com.example.dietplanneraplication;
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.ViewGroup;
import android.widget.Button;
import android.os.Build;

public class FeatureList extends ActionBarActivity {
Button bmiinformation;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_feature_list);
    bmiinformation = (Button) findViewById(R.id.bmiinformation);
    bmiinformation.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            Intent intent =new Intent(getApplicationContext(),BmiCalculaterPage.class);
            startActivity(intent);
            finish();

        }
    });
  }

bmicaller.JAVA

public class BmiCalculaterPage extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_bmi_calculater_page);


}

---

}

您的

活动\u功能\u列表布局.xml中没有名为
bmi信息的id

 bmiinformation = (Button) findViewById(R.id.bmiinformation); // bmiinformation is null as a result

这就是我认为的问题所在。

尝试添加一个id为
bmiinformation
的按钮，功能列表的第26行是什么？@Nabin抱歉，我不明白。FeatureList.xml只有13行。@mimi Post
FeatureList.java
并告诉哪一行是26行？您的日志显示在com.example.dietPlannaplication.FeatureList.onCreate（FeatureList.java:26）10-24 06:35:46.622:E/AndroidRuntime（1102）：在android.app.Activity.performCreate（Activity.java:5008）这意味着您在featureList的第26行有问题。java文件。不谈xmlfile@Nabin更新代码。第26行正好在
finish（）
part之后。我的意思是
}
package com.example.dietplanneraplication;
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.ViewGroup;
import android.widget.Button;
import android.os.Build;

public class FeatureList extends ActionBarActivity {
Button bmiinformation;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_feature_list);
    bmiinformation = (Button) findViewById(R.id.bmiinformation);
    bmiinformation.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            Intent intent =new Intent(getApplicationContext(),BmiCalculaterPage.class);
            startActivity(intent);
            finish();

        }
    });
  }

public class BmiCalculaterPage extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_bmi_calculater_page);


}

 bmiinformation = (Button) findViewById(R.id.bmiinformation); // bmiinformation is null as a result