Question

这是我的代码，应用程序将显示cpu /内存信息和其他内容但在启动时崩溃：

package eu.lucazanini.swipeviews;

import android.annotation.TargetApi;
import android.app.ActionBar;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;

import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.support.v4.app.NotificationCompat;
import android.widget.RadioButton;
import android.widget.TextView;
import android.widget.Toast;


public class MainActivity extends FragmentActivity {

    CollectionPagerAdapter mCollectionPagerAdapter;
        ViewPager mViewPager;
        TextView textOut;
        private TextView cpuInfo;
        private TextView memoryInfo;
 // Notification code
    private static final int SIMPLE_NOTIFICATION_ID = 1;

     NotificationManager mNotificationManager;
     // fine
     @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    @Override
    public void onCreate(Bundle savedInstanceState) {        
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    // Readcpuinfo 
    TextView CPUinfo = (TextView) findViewById(R.id.CPUinfo);
    CPUinfo.setText(getCPUinfo());
    TextView Memoryinfo = (TextView) findViewById(R.id.memoryinfo);
    Memoryinfo.setText(getMemoryInfo()); 
    //fine readcpuinfo
    // Notification code
    mNotificationManager = (NotificationManager) `getSystemService(Context.NOTIFICATION_SERVICE);`

    View btnradio_hindi = findViewById(R.id.radio_hindi);
    // fine
    mCollectionPagerAdapter = new CollectionPagerAdapter(
        getSupportFragmentManager());

    // Set up action bar.
    final ActionBar actionBar = getActionBar();
    actionBar.setDisplayHomeAsUpEnabled(true);

    // Set up the ViewPager, attaching the adapter.
    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setAdapter(mCollectionPagerAdapter);
    }


    /// Inizio creazione funzioni
     private String getMemoryInfo(){
        ProcessBuilder cmd;
        String result = new String();

        try{
        String[] args = {"/system/bin/cat", "/proc/meminfo"};
        cmd = new ProcessBuilder(args);

        Process process = cmd.start();
        InputStream in = process.getInputStream();
        byte[] re = new byte[1024];
        while(in.read(re) != -1){
        System.out.println(new String(re));
        result = result + new String(re);
        }
        in.close();
        } catch(IOException ex){
        ex.printStackTrace();
        }
        return result;
        }
        private String getCPUinfo()
        {
        ProcessBuilder cmd;
        String result="";

        try{
        String[] args = {"/system/bin/cat", "/proc/cpuinfo"};
        cmd = new ProcessBuilder(args);

        Process process = cmd.start();
        InputStream in = process.getInputStream();
        byte[] re = new byte[1024];
        while(in.read(re) != -1){
        System.out.println(new String(re));
        result = result + new String(re);
        }
        in.close();
        } catch(IOException ex){
        ex.printStackTrace();
        }
        return result;
        }

    public Boolean execCommands(String... command) {
        try {
            Runtime rt = Runtime.getRuntime();
            Process process = rt.exec("su");
            DataOutputStream os = new DataOutputStream(process.getOutputStream());

            for(int i = 0; i < command.length; i++) {
                os.writeBytes(command[i] + "\n");
                os.flush();
            }
            os.writeBytes("exit\n");
            os.flush();
            process.waitFor();
        } catch (IOException e) {
            return false;
        } catch (InterruptedException e) {
            return false;
        }
        return true; 
    }

    /**
     * A {@link android.support.v4.app.FragmentStatePagerAdapter} that returns a
     * fragment representing an object in the collection.
     */
    public class CollectionPagerAdapter extends FragmentStatePagerAdapter {

final int NUM_ITEMS = 3; // number of tabs

public CollectionPagerAdapter(FragmentManager fm) {
    super(fm);
}

@Override
public Fragment getItem(int i) {
    Fragment fragment = new TabFragment();
    Bundle args = new Bundle();
    args.putInt(TabFragment.ARG_OBJECT, i);
    fragment.setArguments(args);
    return fragment;
}

@Override
public int getCount() {
    return NUM_ITEMS;
}

@Override
public CharSequence getPageTitle(int position) {

    String tabLabel = null;
    switch (position) {
    case 0:
    tabLabel = getString(R.string.label1);
    break;
    case 1:
    tabLabel = getString(R.string.label2);
    break;
    case 2:
    tabLabel = getString(R.string.label3);
    break;
    }

        return tabLabel;
    }
    }

    /**
     * A dummy fragment representing a section of the app, but that simply
     * displays dummy text.
     */
    public static class TabFragment extends Fragment {

    public static final String ARG_OBJECT = "object";

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

        Bundle args = getArguments();
        int position = args.getInt(ARG_OBJECT);

        int tabLayout = 0;
        switch (position) {
        case 0:
        tabLayout = R.layout.tab1;
        break;
        case 1:
        tabLayout = R.layout.tab2;
        break;
        case 2:
        tabLayout = R.layout.tab3;
        break;
        }

        View rootView = inflater.inflate(tabLayout, container, false);

        return rootView;
    }
    }
    public void onRadioButtonClicked(View view) {

        ((RadioButton) view).isChecked();

        // Check which radio button was clicked
       // switch(view.getId()) {
       // case R.id.radio_hindi:
        //    if (checked)

        switch (view.getId())
        {
        case R.id.radio_hindi:
            String[] commands = {
                    "echo 3 > /proc/sys/vm/drop_caches",
                    "cat /proc/meminfo | awk 'NR == 2'"

            };
            sendSimpleNotification();
            Toast.makeText(this, "Hai liberato memoria! Hai: " + `Runtime.getRuntime().freeMemory() + "", Toast.LENGTH_LONG).show();`
            execCommands(commands);

            String commandText = "echo 'foo' >> /sdcard/foo.txt\necho 'bar' >> `/sdcard/foo.txt";`

            execCommands(commandText.split("\n"));
        break;

        case R.id.radio_english:
        String[] commands1 = {"echo ondemand > `/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor"`,
                    "/sys/devices/system/cpu/cpu1/cpufreq/scaling_governor",
                    "/sys/devices/system/cpu/cpu2/cpufreq/scaling_governor", 
                    "/sys/devices/system/cpu/cpu3/cpufreq/scaling_governor"};
            execCommands(commands1);
            sendSimpleNotificationOndemand();
            Toast.makeText(this, "Hai selezionato il governor Ondemand", `Toast.LENGTH_LONG).show();`
        break;
        case R.id.interactive_btn:
            String[] commands2 = {"echo interactive > `/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor",`
                    "/sys/devices/system/cpu/cpu1/cpufreq/scaling_governor",
                    "/sys/devices/system/cpu/cpu2/cpufreq/scaling_governor", 
                    "/sys/devices/system/cpu/cpu3/cpufreq/scaling_governor"};
            execCommands(commands2);
            sendSimpleNotificationInteractive();
            Toast.makeText(this, "Hai selezionato il governor: Interactive", `Toast.LENGTH_LONG).sho`w();
        break;
        case R.id.conservative_btn:
            String[] commands3 = {"echo conservative > `/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor",`
                    "/sys/devices/system/cpu/cpu1/cpufreq/scaling_governor",
                    "/sys/devices/system/cpu/cpu2/cpufreq/scaling_governor", 
                    "/sys/devices/system/cpu/cpu3/cpufreq/scaling_governor"};
            execCommands(commands3);
            sendSimpleNotificationConservative();
            Toast.makeText(this, "Hai selezionato il governor: Conservative", `Toast.LENGTH_LONG).show();`
        break;
        } 
    }
    protected void cancelSimpleNotification() {
        mNotificationManager.cancel(SIMPLE_NOTIFICATION_ID);
}
private void sendSimpleNotification() {

        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(
                        MainActivity.this);

        // Titolo e testo della notifica
        notificationBuilder.setContentTitle("Boost RAM");
        notificationBuilder.setContentText("Memoria libera: "+ `Runtime.getRuntime().freeMemory() + "bytes");`

    // Testo che compare nella barra di stato non appena compare la notifica
    notificationBuilder.setTicker("Memoria liberata con successo");

    // Data e ora della notifica
    notificationBuilder.setWhen(System.currentTimeMillis());

    // Icona della notifica
    notificationBuilder.setSmallIcon(R.drawable.ic_launcher);

    // Creiamo il pending intent che verrà lanciato quando la notifica
    // viene premuta
    Intent notificationIntent = new Intent(this, MainActivity.class);
    PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                    notificationIntent, 0);

    notificationBuilder.setContentIntent(contentIntent);

    // Impostiamo il suono, le luci e la vibrazione di default
    notificationBuilder.setDefaults(Notification.DEFAULT_SOUND
                    | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE);

    mNotificationManager.notify(SIMPLE_NOTIFICATION_ID,
                        notificationBuilder.build());
}
// Notification per il governor ondemand
private void sendSimpleNotificationOndemand() {

    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(
                    MainActivity.this);

    // Titolo e testo della notifica
    notificationBuilder.setContentTitle("Governor Changed");
    notificationBuilder.setContentText("Hai selezionato il governor Ondemand");

    // Testo che compare nella barra di stato non appena compare la notifica
    notificationBuilder.setTicker("Governor Ondemand settato");

    // Data e ora della notifica
    notificationBuilder.setWhen(System.currentTimeMillis());

    // Icona della notifica
    notificationBuilder.setSmallIcon(R.drawable.ic_launcher);

    // Creiamo il pending intent che verrà lanciato quando la notifica
    // viene premuta
    Intent notificationIntent = new Intent(this, MainActivity.class);
    PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                    notificationIntent, 0);

    notificationBuilder.setContentIntent(contentIntent);

    // Impostiamo il suono, le luci e la vibrazione di default
    notificationBuilder.setDefaults(Notification.DEFAULT_SOUND
                    | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE);

    mNotificationManager.notify(SIMPLE_NOTIFICATION_ID,
                    notificationBuilder.build());
}

//Notification per il governor interactive
private void sendSimpleNotificationInteractive() {

 NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(
                 MainActivity.this);

 // Titolo e testo della notifica
 notificationBuilder.setContentTitle("Governor Changed");
 notificationBuilder.setContentText("Hai selezionato il governor Interactive");

 // Testo che compare nella barra di stato non appena compare la notifica
 notificationBuilder.setTicker("Governor Interactive settato");

 // Data e ora della notifica
 notificationBuilder.setWhen(System.currentTimeMillis());

 // Icona della notifica
 notificationBuilder.setSmallIcon(R.drawable.ic_launcher);

 // Creiamo il pending intent che verrà lanciato quando la notifica
 // viene premuta
 Intent notificationIntent = new Intent(this, MainActivity.class);
 PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                 notificationIntent, 0);

 notificationBuilder.setContentIntent(contentIntent);

 // Impostiamo il suono, le luci e la vibrazione di default
 notificationBuilder.setDefaults(Notification.DEFAULT_SOUND
                 | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE);

 mNotificationManager.notify(SIMPLE_NOTIFICATION_ID,
                 notificationBuilder.build());
}

//Notification per il governor conservative
private void sendSimpleNotificationConservative() {

 NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(
                 MainActivity.this);

 // Titolo e testo della notifica
 notificationBuilder.setContentTitle("Governor Changed");
 notificationBuilder.setContentText("Hai selezionato il governor Conservative");

 // Testo che compare nella barra di stato non appena compare la notifica
 notificationBuilder.setTicker("Governor Conservative settato");

 // Data e ora della notifica
 notificationBuilder.setWhen(System.currentTimeMillis());

 // Icona della notifica
 notificationBuilder.setSmallIcon(R.drawable.ic_launcher);

 // Creiamo il pending intent che verrà lanciato quando la notifica
 // viene premuta
 Intent notificationIntent = new Intent(this, MainActivity.class);
 PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                 notificationIntent, 0);

 notificationBuilder.setContentIntent(contentIntent);

 // Impostiamo il suono, le luci e la vibrazione di default
 notificationBuilder.setDefaults(Notification.DEFAULT_SOUND
                 | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE);

 mNotificationManager.notify(SIMPLE_NOTIFICATION_ID,
                 notificationBuilder.build());
}
}

我不知道为什么但总是在启动时崩溃:(任何建议？日志：

05-27 00:14:09.933: E/AndroidRuntime(6243): FATAL EXCEPTION: main
05-27 00:14:09.933: E/AndroidRuntime(6243): java.lang.RuntimeException: Unable to start `activity ComponentInfo{eu.lucazanini.swipeviews/eu.lucazanini.swipeviews.MainActivity}: `java.lang.NullPointerException
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2357)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `android.app.ActivityThread.access$600(ActivityThread.java:153)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247`)
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `android.os.Handler.dispatchMessage(Handler.java:99)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `android.os.Looper.loop(Looper.java:137)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `android.app.ActivityThread.main(ActivityThread.java:5226)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `java.lang.reflect.Method.invokeNative(Native Method)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `java.lang.reflect.Method.invoke(Method.java:511)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `dalvik.system.NativeStart.main(Native Method)`
05-27 00:14:09.933: E/AndroidRuntime(6243): Caused by: java.lang.NullPointerException
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `eu.lucazanini.swipeviews.MainActivity.onCreate(MainActivity.java:56)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `android.app.Activity.performCreate(Activity.java:5104)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     at `android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2261)`
05-27 00:14:09.933: E/AndroidRuntime(6243):     ... 11 mor

e

如果需要其他信息请告诉我。非常感谢你

java的第56行：

CPUinfo.setText(getCPUinfo());

我有4 xml，因为我有一个swipeview。 main.xml，tab1，tab2和tab3.xml。 main.xml中：

<android.support.v4.view.ViewPager `xmlns:android="http://schemas.android.com/apk/res/android"`
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent">

<!--
This title strip will display the currently visible page title, as well as the page
titles for adjacent pages.
-->
<android.support.v4.view.PagerTitleStrip android:id="@+id/pager_title_strip"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="top"
    android:background="#33b5e5"
    android:textColor="#fff"
    android:paddingTop="4dp"
    android:paddingBottom="4dp" />

</android.support.v4.view.ViewPager>

tab1.xml

<?xml version="1.0" encoding="utf-8"?>
<RadioGroup xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<TextView
    android:id="@+id/textView5"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:layout_marginTop="10dp"
    android:text="CHANGE GOVERNOR"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:textColor="#FF8000"
    tools:ignore="HardcodedText" />

<TextView
    android:id="@+id/textView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:text="Change the CPU Governor: "
    android:textColor="#00AEEF"
    tools:ignore="HardcodedText" />

<RadioButton
    android:id="@+id/radio_english"
    android:layout_width="201dp"
    android:layout_height="55dp"
    android:onClick="onRadioButtonClicked"
    android:text="OnDemand"
    tools:ignore="HardcodedText" />

<RadioButton
    android:id="@+id/interactive_btn"
    android:layout_width="200dp"
    android:layout_height="55dp"
    android:onClick="onRadioButtonClicked"
    android:text="Interactive"
    tools:ignore="HardcodedText" />

<RadioButton
    android:id="@+id/conservative_btn"
    android:layout_width="200dp"
    android:layout_height="55dp"
    android:layout_gravity="fill"
    android:onClick="onRadioButtonClicked"
    android:text="Conservative"
    tools:ignore="HardcodedText" />

<TextView
    android:id="@+id/AndroidCPUInfo"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Android CPU Info.:"
    tools:ignore="HardcodedText" />

<TextView
    android:id="@+id/CPUinfo"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    tools:ignore="SelectableText" />

</RadioGroup>

tab2.xml：

<?xml version="1.0" encoding="utf-8"?>
<RadioGroup xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >

<TextView
    android:id="@+id/textView4"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:layout_marginTop="10dp"
    android:text="BOOST RAM"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:textColor="#FF8000"
    tools:ignore="HardcodedText" />

<TextView
    android:id="@+id/textView1"
    android:layout_width="296dp"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:text="Boost your RAM memory and drop the cache to speed up your phone! Click `the Radio Button."`
    android:textColor="#00AEEF"
    tools:ignore="HardcodedText" />

<RadioButton
    android:id="@+id/radio_hindi"
    android:layout_width="match_parent"
    android:layout_height="64dp"
    android:onClick="onRadioButtonClicked"
    android:text="Drop the cache and boost your RAM"
    tools:ignore="HardcodedText" />

<TextView
    android:id="@+id/memo_text"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Memory Info:"
    android:textColor="#0000FF"
    tools:ignore="HardcodedText" />

<TextView
    android:id="@+id/memoryinfo"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    tools:ignore="SelectableText" />

</RadioGroup>

和tab3.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/tab3"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="top"
    android:layout_marginLeft="10dp"
    android:text="Version: 1.0.0"
    tools:ignore="HardcodedText" />

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="top"
    android:layout_marginLeft="10dp"
    android:text="Author: Davide Dellai"
    tools:ignore="DuplicateIds,HardcodedText" />

<TextView
    android:id="@+id/textView3"
    android:layout_width="180dp"
    android:layout_height="wrap_content"
    android:layout_gravity="top"
    android:layout_marginLeft="10dp"
android:autoLink="email"
    android:text="Email id: name.surname@gmail.com"
    tools:ignore="HardcodedText" />

</LinearLayout>

Answer 1

这是因为您的R.id.CPUinfo TextView和R.id.memoryinfo TextView没有驻留在R.layout.main中，您应该在适当的Fragment onCreateView中进行此调用

示例：

public static class TabFragment extends Fragment {

    public static final String ARG_OBJECT = "object";

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

        Bundle args = getArguments();
        int position = args.getInt(ARG_OBJECT);

        int tabLayout = 0;
        switch (position) {
        case 0:
        tabLayout = R.layout.tab1;
        break;
        case 1:
        tabLayout = R.layout.tab2;
        break;
        case 2:
        tabLayout = R.layout.tab3;
        break;
        }

        View rootView = inflater.inflate(tabLayout, container, false);

        if (tabLayout == R.layout.tab1) {    
            TextView CPUinfo = (TextView) rootView.findViewById(R.id.CPUinfo);
            CPUinfo.setText(getCPUinfo());
            TextView Memoryinfo = (TextView) rootView.findViewById(R.id.memoryinfo);
            Memoryinfo.setText(getMemoryInfo());
        }    
        return rootView;
    }
}

问题出在哪里？我的应用程序在启动时崩溃了

1 个答案: