Question

我有一个活动，让我注册或只是登录，当用户登录时，显示四个片段，可以通过可滚动的选项卡导航，最后一个片段有一个注销按钮，我需要注销按钮1）直接从parse.com注销，2）让用户进入他们可以注册或登录的活动。

这是我到目前为止的代码

这是签署或注册活动

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

    // Log in button click handler
    ((Button) findViewById(R.id.login)).setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            // Starts an intent of the log in activity
            startActivity(new Intent(SignUpOrLogInActivity.this, LoginActivity.class));
        }
    });

    // Sign up button click handler
    ((Button) findViewById(R.id.signup)).setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            // Starts an intent for the sign up activity
            startActivity(new Intent(SignUpOrLogInActivity.this, SignUpActivity.class));
        }
    });
}

这是设置了登出按钮的设置片段

    @Override
    public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
        return inflater.inflate(R.layout.setup_fragment,container,false);
    }
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        logout = (Button) getView().findViewById(R.id.logout_button);

        // Logout Button Click Listener
        logout.setOnClickListener(new OnClickListener() {

            public void onClick(View view) {
                // Logout current user
                ParseUser.logOut();
                startActivity(new Intent(getActivity(), SignUpOrLogInActivity.class));

            }

        });

    }
}

问题是1）当我运行应用程序时，它首先从可滚动的标签（片段）开始，而不是在登录或注册活动和2）当我去设置片段所在的日志out按钮位于应用程序崩溃状态，并显示一条消息，说“不幸的是，您的应用程序已停止。

这里是明显的

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme"
    android:name=".ParseStarter">
    <activity
        android:screenOrientation="portrait"
        android:name=".MainActivity"
        android:label="@string/app_name" >

    </activity>

    <activity android:name=".DispatchActivity"
        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=".LoginActivity" />
    <activity android:name=".SignUpActivity" />
    <activity android:name=".SignUpOrLogInActivity" />
</application>

这是LOGCAT

Process: com.sebasdeldihotmail.mediocre, PID: 1863
    java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
            at com.sebasdeldihotmail.mediocre.Setup.onCreate(Setup.java:35)
            at android.support.v4.app.Fragment.performCreate(Fragment.java:1763)
            at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:913)
            at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
            at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
            at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489)
            at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:486)
            at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
            at android.support.v4.view.ViewPager.populate(ViewPager.java:1073)
            at android.support.v4.view.ViewPager.populate(ViewPager.java:919)
            at android.support.v4.view.ViewPager$3.run(ViewPager.java:249)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
            at android.view.Choreographer.doCallbacks(Choreographer.java:580)
            at android.view.Choreographer.doFrame(Choreographer.java:549)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
12-14 00:26:52.791    1863-1863/com.sebasdeldihotmail.mediocre I/Process﹕ Sending signal. PID: 1863 SIG: 9

此处是调度活动类

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

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    logout = (Button) getView().findViewById(R.id.logout_button);

    // Logout Button Click Listener
    logout.setOnClickListener(new OnClickListener() {

        public void onClick(View view) {
            // Logout current user
            ParseUser.logOut();
            startActivity(new Intent(getActivity(), SignUpOrLogInActivity.class));

        }

    });

}

感谢您花时间阅读这篇文章，我真的很欣赏它。

Answer 1

对于问题1：您在清单文件中写了这个

<activity android:name=".DispatchActivity"
    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=".LoginActivity" />
<activity android:name=".SignUpActivity" />
<activity android:name=".SignUpOrLogInActivity" />

现在改变它

<activity android:name=".SignUpOrLogInActivity"
    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=".LoginActivity" />
<activity android:name=".SignUpActivity" />

问题2：现在查看你的注销按钮对象...它实际上是空的..你在onCreateView中扩展了一个布局..所以你需要创建一个与该视图相关联的按钮对象..所以在onCreateView()方法中这样做

@Override
public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
    View root = inflater.inflate(R.layout.setup_fragment,container,false);
    Button logout = (Button)root.findViewById(R.id.logout_button);
    logout.setOnClickListener(new OnClickListener() {

        public void onClick(View view) {
            // Logout current user
            ParseUser.logOut();
            startActivity(new Intent((ParentActivity)getActivity(), SignUpOrLogInActivity.class));

        }

    });
  return root;
}

希望它有效......如果遇到任何问题......只需评论一下......谢谢

如何制作一个parse.com注销按钮带我去另一个让我登录或注册的活动？

1 个答案: