致命意外：主要发生在Android 4.x上，而不是Android 2.X

Question

I am getting some errors when trying to run my android app on an emulator that is running any version of Android 4.x but it works fine on any version of Android 2.X.

package com.EXCLUDED_FOR_PRIVACY.EXCLUDED_FOR_PRIVACY;

import android.app.Activity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.TabHost;
import android.widget.TabHost.OnTabChangeListener;
import android.widget.TabHost.TabSpec;
import android.widget.ImageView;
import android.graphics.Color;

public class EXCLUDED_FOR_PRIVACY extends Activity {

    public int WebView1Bool=0;
    public int WebView2Bool=0;
    public int WebView3Bool=0;
    public int WebView4Bool=0;
    private TabHost tabs;

    private void setupTabHost() {
        tabs = (TabHost) findViewById(R.id.my_tabhost);
        tabs.setup();
    }

    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        setupTabHost();
        tabs.getTabWidget().setDividerDrawable(R.drawable.tab_divider);

        setupTab(new ImageView(this), 1);
        setupTab(new ImageView(this), 2);
        setupTab(new ImageView(this), 3);
        setupTab(new ImageView(this), 4);

        WebView mWebView1;
        mWebView1 = (WebView) findViewById(R.id.webview1);
        mWebView1.setBackgroundColor(Color.parseColor("#a3a3a3"));
        mWebView1.setBackgroundColor(0);
        mWebView1.getSettings().setJavaScriptEnabled(true);
        mWebView1.setWebViewClient(new MobileClient());
        mWebView1.loadUrl("EXCLUDED_FOR_PRIVACY");
        WebView1Bool=1;

        tabs.getTabWidget().getChildAt(0).setOnClickListener(new OnClickListener(){
            @Override
            public void onClick(View v){
                tabs.setCurrentTab(0);
                if(WebView1Bool==0){
                    WebView mWebView1;
                    mWebView1 = (WebView) findViewById(R.id.webview1);
                    mWebView1.setBackgroundColor(Color.parseColor("#a3a3a3"));
                    mWebView1.setBackgroundColor(0);
                    mWebView1.getSettings().setJavaScriptEnabled(true);
                    mWebView1.setWebViewClient(new MobileClient());
                    mWebView1.loadUrl("EXCLUDED_FOR_PRIVACY");
                    WebView1Bool=1;
                }
            }
        });

        tabs.getTabWidget().getChildAt(2).setOnClickListener(new OnClickListener(){
            @Override
            public void onClick(View v){
                tabs.setCurrentTab(1);
                if(WebView2Bool==0){
                    WebView mWebView2;
                    mWebView2 = (WebView) findViewById(R.id.webview2);
                    mWebView2.setBackgroundColor(Color.parseColor("#a3a3a3"));
                    mWebView2.setBackgroundColor(0);
                    mWebView2.getSettings().setJavaScriptEnabled(true);
                    mWebView2.setWebViewClient(new MobileClient());
                    mWebView2.loadUrl("EXCLUDED_FOR_PRIVACY");
                    WebView2Bool=1;
                }
            }
        });

        tabs.getTabWidget().getChildAt(4).setOnClickListener(new OnClickListener(){
            @Override
            public void onClick(View v){
                tabs.setCurrentTab(2);
                if(WebView3Bool==0){
                    WebView mWebView3 = (WebView) findViewById(R.id.webview3);
                    mWebView3.setBackgroundColor(Color.parseColor("#a3a3a3"));
                    mWebView3.setBackgroundColor(0);
                    mWebView3.getSettings().setJavaScriptEnabled(true);
                    mWebView3.setWebViewClient(new MobileClient());
                    mWebView3.loadUrl("EXCLUDED_FOR_PRIVACY");
                    WebView3Bool=1;
                }
            }
        });

        tabs.getTabWidget().getChildAt(6).setOnClickListener(new OnClickListener(){
            @Override
            public void onClick(View v){
                tabs.setCurrentTab(3);
                if(WebView4Bool==0){
                    WebView mWebView4;
                    mWebView4 = (WebView) findViewById(R.id.webview4);
                    mWebView4.setBackgroundColor(Color.parseColor("#a3a3a3"));
                    mWebView4.setBackgroundColor(0);
                    mWebView4.getSettings().setJavaScriptEnabled(true);
                    mWebView4.setWebViewClient(new MobileClient());
                    mWebView4.loadUrl("EXCLUDED_FOR_PRIVACY");
                    WebView4Bool=1;
                }
            }
        });
    }

    private class MobileClient extends WebViewClient {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            view.loadUrl(url);
            return true;
        }
    }

    private void setupTab(final View view, final int i) {
        View createTabView_view = LayoutInflater.from(tabs.getContext()).inflate(R.layout.tabs_bg, null);
        ImageView createTabView_tv = (ImageView) createTabView_view.findViewById(R.id.tabsImage);
        if(i==1){
            TabSpec tabSpec = tabs.newTabSpec("EXCLUDED_FOR_PRIVACY");
            createTabView_tv.setImageResource(R.drawable.ic_discounts);
            tabSpec.setIndicator(createTabView_view);
            tabSpec.setContent(R.id.webview1);
            tabs.addTab(tabSpec);
        } else if(i==2){
            TabSpec tabSpec = tabs.newTabSpec("EXCLUDED_FOR_PRIVACY");
            createTabView_tv.setImageResource(R.drawable.ic_specials);
            tabSpec.setIndicator(createTabView_view);
            tabSpec.setContent(R.id.webview2);
            tabs.addTab(tabSpec);
        } else if(i==3){
            TabSpec tabSpec = tabs.newTabSpec("EXCLUDED_FOR_PRIVACY");
            createTabView_tv.setImageResource(R.drawable.ic_directory);
            tabSpec.setIndicator(createTabView_view);
            tabSpec.setContent(R.id.webview3);
            tabs.addTab(tabSpec);
        } else if(i==4){
            TabSpec tabSpec = tabs.newTabSpec("EXCLUDED_FOR_PRIVACY");
            createTabView_tv.setImageResource(R.drawable.ic_membership);
            tabSpec.setIndicator(createTabView_view);
            tabSpec.setContent(R.id.webview4);
            tabs.addTab(tabSpec);
        }
    }
}

Here are the errors I am seeing

09-24 13:11:25.329: E/Trace(1151):              error opening trace file: No such file or directory (2)
09-24 13:11:25.539: D/dalvikvm(1151):           GC_FOR_ALLOC freed 43K, 4% free 8316K/8583K, paused 42ms, total 45ms
09-24 13:11:25.549: I/dalvikvm-heap(1151):      Grow heap (frag case) to 8.829MB for 691216-byte allocation
09-24 13:11:25.669: D/dalvikvm(1151):           GC_CONCURRENT freed <1K, 4% free 8990K/9287K, paused 75ms+6ms, total 124ms
09-24 13:11:25.829: D/gralloc_goldfish(1151):   Emulator without GPU emulation detected.
09-24 13:11:26.209: I/Choreographer(1151):      Skipped 42 frames!  The application may be doing too much work on its main thread.
09-24 13:11:26.379: I/Choreographer(1151):      Skipped 44 frames!  The application may be doing too much work on its main thread.
09-24 13:11:27.509: I/Choreographer(1151):      Skipped 54 frames!  The application may be doing too much work on its main thread.
09-24 13:11:28.319: D/AndroidRuntime(1151):     Shutting down VM
09-24 13:11:28.319: W/dalvikvm(1151):           threadid=1: thread exiting with uncaught exception (group=0x40a13300)
09-24 13:11:28.379: E/AndroidRuntime(1151):     FATAL EXCEPTION: main
09-24 13:11:28.379: E/AndroidRuntime(1151):     java.lang.RuntimeException: Unable to start activity ComponentInfo{com.EXCLUDED.EXCLUDED/com.EXCLUDED.EXCLUDED.EXCLUDED}: java.lang.NullPointerException
09-24 13:11:28.379: E/AndroidRuntime(1151):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at android.app.ActivityThread.access$600(ActivityThread.java:130)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at android.os.Looper.loop(Looper.java:137)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at android.app.ActivityThread.main(ActivityThread.java:4745)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at java.lang.reflect.Method.invokeNative(Native Method)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at java.lang.reflect.Method.invoke(Method.java:511)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at dalvik.system.NativeStart.main(Native Method)
09-24 13:11:28.379: E/AndroidRuntime(1151):     Caused by: java.lang.NullPointerException
09-24 13:11:28.379: E/AndroidRuntime(1151):     at com.EXCLUDED.EXCLUDED.EXCLUDED.onCreate(EXCLUDED.java:85)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at android.app.Activity.performCreate(Activity.java:5008)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
09-24 13:11:28.379: E/AndroidRuntime(1151):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
09-24 13:11:28.379: E/AndroidRuntime(1151):     ... 11 more
09-24 13:11:30.289: I/Process(1151):            Sending signal. PID: 1151 SIG: 9

I apologize if this is something really simple that any java developer would know, I have to admit I barely know what I am doing in Java but am under the gun to get this built. Thank you very much for any help.

Answer 1

Get rid of all the tabs.getTabWidget().getChildAt(...).setOnClickListener() crap, replacing it with a single TabHost.OnTabChangeListener that you register with your TabHost , to find out when the user changes tabs. Your existing code assumes a particular internal structure of a TabWidget , and that assumption is unreliable, as you are discovering.