Question

我有这个logcat错误，它无法启动活动..

04-25 17:51:54.889: E/AndroidRuntime(1238): Process: com.mobilebasedtexttosignlanguageconverter, PID: 1238
04-25 17:51:54.889: E/AndroidRuntime(1238): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobilebasedtexttosignlanguageconverter/com.mobilebasedtexttosignlanguageconverter.MainActivity}: java.lang.NullPointerException
04-25 17:51:54.889: E/AndroidRuntime(1238):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at android.os.Handler.dispatchMessage(Handler.java:102)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at android.os.Looper.loop(Looper.java:136)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at java.lang.reflect.Method.invokeNative(Native Method)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at java.lang.reflect.Method.invoke(Method.java:515)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at dalvik.system.NativeStart.main(Native Method)
04-25 17:51:54.889: E/AndroidRuntime(1238): Caused by: java.lang.NullPointerException
04-25 17:51:54.889: E/AndroidRuntime(1238):     at com.mobilebasedtexttosignlanguageconverter.MainActivity.onCreate(MainActivity.java:34)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at android.app.Activity.performCreate(Activity.java:5231)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-25 17:51:54.889: E/AndroidRuntime(1238):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)

这是我的主要活动..

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

    if (savedInstanceState == null) {
        getFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
    }

    Button conv = (Button)findViewById(R.id.btn_conv);
    //Button inst = (Button)findViewById(R.id.btn_ins);
    //Button view = (Button)findViewById(R.id.btn_view);
    //Button ext = (Button)findViewById(R.id.btn_ex);

    conv.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            Intent conv = new Intent(MainActivity.this, ConvertSubMenu.class);
            startActivity(conv);
        }
    });

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container,
                false);
        return rootView;
    }
}

请帮助我，我刚刚安装了最新的eclipse，我对android的更新的sdk管理器有问题，因为它对我来说很新..

Answer 1

我的猜测是findViewById正在返回null。确保您的布局中有一个ID为btn_conv的按钮。

android无法启动组件信息

1 个答案: