切换到选项卡布局的Android登录屏幕？

嗨，我有一个应用程序写的，正确登录后会带你到另一个页面。这是主页的代码，当我让它指向一个带有图像的普通页面时，它工作得很好：

package com.example.loginscreen;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;


public class MainActivity extends Activity {

   private EditText  username=null;
   private EditText  password=null;
   private TextView attempts;
   private Button login;
   int counter = 3;


   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      username = (EditText)findViewById(R.id.editText1);
      password = (EditText)findViewById(R.id.editText2);
      attempts = (TextView)findViewById(R.id.textView5);
      attempts.setText(Integer.toString(counter));
      login = (Button)findViewById(R.id.button1);
   }

   public void login(View view){
      if(username.getText().toString().equals("mark") && 
      password.getText().toString().equals("mark")){
      Toast.makeText(getApplicationContext(), "Login Successful!", 
      Toast.LENGTH_LONG).show();
      startActivity(new Intent(MainActivity.this,Loading.class)); 
       }    
   else{
      Toast.makeText(getApplicationContext(), "Wrong Credentials",
      Toast.LENGTH_SHORT).show();
      attempts.setBackgroundColor(Color.RED);   
      counter--;
      attempts.setText(Integer.toString(counter));
      if(counter==0){
         login.setEnabled(false);
      }

       }

 }
    @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;
    }

 }

切换到具有以下活动的选项卡布局：

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class HomePage extends Activity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        TextView textview = new TextView(this);
        textview.setText("Overview");
        setContentView(textview);
    }
}



package com.example.loginscreen;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class HomePage2 extends Activity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        TextView textview = new TextView(this);
        textview.setText("Card Summary");
        setContentView(textview);
    }
}



package com.example.loginscreen;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class HomePage3 extends Activity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        TextView textview = new TextView(this);
        textview.setText("Details");
        setContentView(textview);
    }
}

所有这些都通过以下链接：

package com.example.loginscreen;

import android.app.TabActivity;
import android.content.Intent;
import android.content.res.Resources;
import android.os.Bundle;
import android.widget.TabHost;
import android.widget.TabHost.TabSpec;

@SuppressWarnings("deprecation")
public class LinkTabs extends TabActivity {

        public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.link_main);

        Resources ressources = getResources(); 
        TabHost tabHost = getTabHost(); 

        // First tab
        Intent intentAndroid = new Intent().setClass(this, HomePage.class);
        TabSpec tabSpecHomePage = tabHost
          .newTabSpec("HomePage")
          .setIndicator("", ressources.getDrawable(R.drawable.overview))
          .setContent(intentAndroid);

        // Second tab
        Intent intentApple = new Intent().setClass(this, HomePage2.class);
        TabSpec tabSpecHomePage2 = tabHost
          .newTabSpec("HomePage2")
          .setIndicator("", ressources.getDrawable(R.drawable.overview))
          .setContent(intentApple);

            // Third tab
        Intent intentWindows = new Intent().setClass(this, HomePage3.class);
        TabSpec tabSpecHomePage3 = tabHost
          .newTabSpec("HomePage3")
          .setIndicator("", ressources.getDrawable(R.drawable.overview))
          .setContent(intentWindows);


        // add all tabs 
        tabHost.addTab(tabSpecHomePage);
        tabHost.addTab(tabSpecHomePage2);
        tabHost.addTab(tabSpecHomePage3);


        //set Windows tab as default (zero based)
        tabHost.setCurrentTab(2);
    }

}

但每当我运行应用程序时，它都会启动第一个活动，这会让一切正常，但如果你正确登录，应用程序就会停止。没有错误，以下是清单：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.loginscreen"
   android:versionCode="1"
   android:versionName="1.0" >

   <uses-sdk
  android:minSdkVersion="10"
  android:targetSdkVersion="17" />

<application
  android:allowBackup="true"
  android:icon="@drawable/ic_launcher"
  android:label="@string/app_name"
  android:theme="@style/AppTheme" >

  <activity
     android:name="com.example.loginscreen.MainActivity"
     android:label="@string/app_name" >
     <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
     </intent-filter>
  </activity>
<activity android:name=".HomePage" />
<activity android:name=".HomePage2" />
<activity android:name=".HomePage3" />
</application>
</manifest>

您的错误消息是：

Unable to find explicit activity class {com.example.loginscreen/com.example.loginscreen.LinkTabs}; have you declared this activity in your AndroidManifest.xml?

---

这个问题的答案很明显：您的清单中没有

标记。只要添加它，它就会工作。

应用程序就会停止

，这意味着什么？会发生什么？你看到崩溃对话框了吗？如果是这样：你能在Logcat中看到什么？当我运行它时，ut说“不幸的是LoginScreen已停止”，我将发布Logcat。你能为你的登录页面添加XML吗？如果将登录页面设置为启动应用程序的默认XML，会发生什么情况？这也会崩溃吗？我没有看到任何logcat。。。

<?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/tabhost"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="5dp">
    <TabWidget
        android:id="@android:id/tabs"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
    <FrameLayout
        android:id="@android:id/tabcontent"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:padding="5dp" />
</LinearLayout>
</TabHost>

06-19 16:25:04.175: E/AndroidRuntime(16791): FATAL EXCEPTION: main
06-19 16:25:04.175: E/AndroidRuntime(16791): java.lang.IllegalStateException: Could not execute method of the activity
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.view.View$1.onClick(View.java:3603)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.view.View.performClick(View.java:4103)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.view.View$PerformClick.run(View.java:17117)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.os.Handler.handleCallback(Handler.java:615)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.os.Handler.dispatchMessage(Handler.java:92)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.os.Looper.loop(Looper.java:137)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.app.ActivityThread.main(ActivityThread.java:4744)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at java.lang.reflect.Method.invokeNative(Native Method)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at java.lang.reflect.Method.invoke(Method.java:511)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at dalvik.system.NativeStart.main(Native Method)
06-19 16:25:04.175: E/AndroidRuntime(16791): Caused by: java.lang.reflect.InvocationTargetException
06-19 16:25:04.175: E/AndroidRuntime(16791):    at java.lang.reflect.Method.invokeNative(Native Method)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at java.lang.reflect.Method.invoke(Method.java:511)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.view.View$1.onClick(View.java:3598)
06-19 16:25:04.175: E/AndroidRuntime(16791):    ... 11 more
06-19 16:25:04.175: E/AndroidRuntime(16791): Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.loginscreen/com.example.loginscreen.LinkTabs}; have you declared this activity in your AndroidManifest.xml?
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1541)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.app.Instrumentation.execStartActivity(Instrumentation.java:1416)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.app.Activity.startActivityForResult(Activity.java:3351)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.app.Activity.startActivityForResult(Activity.java:3312)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.app.Activity.startActivity(Activity.java:3522)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at android.app.Activity.startActivity(Activity.java:3490)
06-19 16:25:04.175: E/AndroidRuntime(16791):    at com.example.loginscreen.MainActivity.login(MainActivity.java:40)
06-19 16:25:04.175: E/AndroidRuntime(16791):    ... 14 more

Unable to find explicit activity class {com.example.loginscreen/com.example.loginscreen.LinkTabs}; have you declared this activity in your AndroidManifest.xml?