java - 我无法绑定(bind)到 "View"中的 fragment 。 getView() 不起作用 :(

Question

无法创建对象，认为Tab1.java中包含错误

Tab1 中包含计时器。因此，我送你去看“布局”。

Tab.java

package com.android.example;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.os.Handler;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;

import java.text.SimpleDateFormat;
import java.util.Date;


public class Tab1 extends Fragment {

    private TextView tvDay, tvHour, tvMinute, tvSecond, tvEvent;
    private LinearLayout linearLayout1, linearLayout2;
    private Handler handler;
    private Runnable runnable;

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.tab_1, container, false);
        initUI();
        countDownStart();
        return v;
    }


    @SuppressLint("SimpleDateFormat")
    private void initUI() {
        linearLayout1 = (LinearLayout) getView().findViewById(R.id.ll1);
        linearLayout2 = (LinearLayout) getView().findViewById(R.id.ll2);
        tvDay = (TextView) getView().findViewById(R.id.txtTimerDay);
        tvHour = (TextView) getView().findViewById(R.id.txtTimerHour);
        tvMinute = (TextView) getView().findViewById(R.id.txtTimerMinute);
        tvSecond = (TextView) getView().findViewById(R.id.txtTimerSecond);
        tvEvent = (TextView) getView().findViewById(R.id.tvevent);
    }

    // //////////////COUNT DOWN START/////////////////////////
    public void countDownStart() {
        handler = new Handler();
        runnable = new Runnable() {
            @Override
            public void run() {
                handler.postDelayed(this, 1000);
                try {
                    SimpleDateFormat dateFormat = new SimpleDateFormat(
                            "yyyy-MM-dd");
                    // Here Set your Event Date
                    Date futureDate = dateFormat.parse("2016-12-30");
                    Date currentDate = new Date();
                    if (!currentDate.after(futureDate)) {
                        long diff = futureDate.getTime()
                                - currentDate.getTime();
                        long days = diff / (24 * 60 * 60 * 1000);
                        diff -= days * (24 * 60 * 60 * 1000);
                        long hours = diff / (60 * 60 * 1000);
                        diff -= hours * (60 * 60 * 1000);
                        long minutes = diff / (60 * 1000);
                        diff -= minutes * (60 * 1000);
                        long seconds = diff / 1000;
                        tvDay.setText("" + String.format("%02d", days));
                        tvHour.setText("" + String.format("%02d", hours));
                        tvMinute.setText("" + String.format("%02d", minutes));
                        tvSecond.setText("" + String.format("%02d", seconds));
                    } else {
                        linearLayout1.setVisibility(View.VISIBLE);
                        linearLayout2.setVisibility(View.GONE);
                        tvEvent.setText("Android Event Start");
                        handler.removeCallbacks(runnable);
                        // handler.removeMessages(0);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        };
        handler.postDelayed(runnable, 0);
    }

    // //////////////COUNT DOWN END/////////////////////////
}

MainActivity.java然后连接 fragment

package com.android.example;

import android.content.Context;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity {

    // Declaring Your View and Variables

    Toolbar toolbar;
    ViewPager pager;
    ViewPagerAdapter adapter;
    SlidingTabLayout tabs;

    int Numboftabs =3;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        CharSequence Titles[]= {getResources().getString(R.string.titles), getResources().getString(R.string.result), getResources().getString(R.string.contacts)};


        // Creating The Toolbar and setting it as the Toolbar for the activity

        toolbar = (Toolbar) findViewById(R.id.tool_bar);
        setSupportActionBar(toolbar);


        // Creating The ViewPagerAdapter and Passing Fragment Manager, Titles fot the Tabs and Number Of Tabs.
        adapter =  new ViewPagerAdapter(getSupportFragmentManager(),Titles,Numboftabs);

        // Assigning ViewPager View and setting the adapter
        pager = (ViewPager) findViewById(R.id.pager);
        pager.setAdapter(adapter);

        // Assiging the Sliding Tab Layout View
        tabs = (SlidingTabLayout) findViewById(R.id.tabs);
        tabs.setDistributeEvenly(true); // To make the Tabs Fixed set this true, This makes the tabs Space Evenly in Available width

        // Setting Custom Color for the Scroll bar indicator of the Tab View
        tabs.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() {
            @Override
            public int getIndicatorColor(int position) {
                return getResources().getColor(R.color.tabsScrollColor);
            }
        });

        // Setting the ViewPager For the SlidingTabsLayout
        tabs.setViewPager(pager);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu, 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();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

tab_1.xml这是布局

<?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:layout_width="match_parent"
    android:layout_height="match_parent" >

    <LinearLayout
        android:id="@+id/ll1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="10dp"
        android:background="@drawable/counter_back"
        android:gravity="center"
        android:orientation="horizontal"
        android:visibility="gone" >

        <TextView
            android:id="@+id/tvevent"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center_horizontal|center_vertical"
            android:singleLine="true"
            android:text="Android Event Start"
            android:textColor="#fff"
            android:textSize="24sp"
            android:textStyle="bold" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/ll2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_marginTop="10dp"
        android:background="@drawable/counter_back"
        android:gravity="center"
        android:orientation="horizontal"
        android:visibility="visible" >

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@drawable/counter_back"
            android:gravity="center"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/txtTimerDay"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="3"
                android:gravity="center"
                android:text="00"
                android:textAppearance="?android:attr/textAppearanceLarge"
                android:textColor="#fff" />

            <TextView
                android:id="@+id/txt_TimerDay"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:gravity="center_horizontal"
                android:text="Days"
                android:textAppearance="?android:attr/textAppearanceSmall"
                android:textColor="#fff" />
        </LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@drawable/counter_back"
            android:gravity="center"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/txtTimerHour"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="3"
                android:gravity="center"
                android:text="00"
                android:textAppearance="?android:attr/textAppearanceLarge"
                android:textColor="#fff" />

            <TextView
                android:id="@+id/txt_TimerHour"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:gravity="center_horizontal"
                android:text="Hour"
                android:textAppearance="?android:attr/textAppearanceSmall"
                android:textColor="#fff" />
        </LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@drawable/counter_back"
            android:gravity="center"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/txtTimerMinute"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="3"
                android:gravity="center"
                android:text="00"
                android:textAppearance="?android:attr/textAppearanceLarge"
                android:textColor="#fff" />

            <TextView
                android:id="@+id/txt_TimerMinute"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:gravity="center_horizontal"
                android:text="Minute"
                android:textAppearance="?android:attr/textAppearanceSmall"
                android:textColor="#fff" />
        </LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@drawable/counter_back"
            android:gravity="center"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/txtTimerSecond"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="3"
                android:gravity="center"
                android:text="00"
                android:textAppearance="?android:attr/textAppearanceLarge"
                android:textColor="#fff" />

            <TextView
                android:id="@+id/txt_TimerSecond"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:gravity="center_horizontal"
                android:text="Second"
                android:textAppearance="?android:attr/textAppearanceSmall"
                android:textColor="#fff" />
        </LinearLayout>
    </LinearLayout>

</LinearLayout>

等级错误:我无法找出错误。请不要“写”，因为我是初学者程序员:)

03-19 18:00:55.154 28193-28193/? E/Zygote: v2
03-19 18:00:55.154 28193-28193/? I/libpersona: KNOX_SDCARD checking this for 10140
03-19 18:00:55.154 28193-28193/? I/libpersona: KNOX_SDCARD not a persona
03-19 18:00:55.154 28193-28193/? I/SELinux: Function: selinux_compare_spd_ram , priority [2] , priority version is VE=SEPF_SM-A300F_5.0.2-1_0026
03-19 18:00:55.154 28193-28193/? E/SELinux: [DEBUG] get_category: variable seinfo: default sensitivity: NULL, cateogry: NULL
03-19 18:00:55.154 28193-28193/? I/art: Late-enabling -Xcheck:jni
03-19 18:00:55.174 28193-28193/? D/TimaKeyStoreProvider: in addTimaSignatureService
03-19 18:00:55.184 28193-28193/? D/TimaKeyStoreProvider: Cannot add TimaSignature Service, License check Failed
03-19 18:00:55.184 28193-28193/? D/ActivityThread: Added TimaKesytore provider
03-19 18:00:55.374 28193-28193/com.android.example D/DisplayManager: DisplayManager()
03-19 18:00:55.714 28193-28240/com.android.example D/OpenGLRenderer: Render dirty regions requested: true
03-19 18:00:55.784 28193-28193/com.android.example W/FragmentManager: moveToState: Fragment state for Tab2{3edefe8b #0 id=0x7f0c0052} not updated inline; expected state 3 found 2
03-19 18:00:55.834 28193-28193/com.android.example D/AndroidRuntime: Shutting down VM
03-19 18:00:55.844 28193-28193/com.android.example E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                 Process: com.android.example, PID: 28193
                                                                                 java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
                                                                                     at com.android.example.Tab1.initUI(Tab1.java:36)
                                                                                     at com.android.example.Tab1.onCreateView(Tab1.java:28)
                                                                                     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1974)
                                                                                     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
                                                                                     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252)
                                                                                     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
                                                                                     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
                                                                                     at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:570)
                                                                                     at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:164)
                                                                                     at android.support.v4.view.ViewPager.populate(ViewPager.java:1177)
                                                                                     at android.support.v4.view.ViewPager.populate(ViewPager.java:1025)
                                                                                     at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1545)
                                                                                     at android.view.View.measure(View.java:17826)
                                                                                     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5653)
                                                                                     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
                                                                                     at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
                                                                                     at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
                                                                                     at android.view.View.measure(View.java:17826)
                                                                                     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5653)
                                                                                     at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
                                                                                     at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
                                                                                     at android.view.View.measure(View.java:17826)
                                                                                     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5653)
                                                                                     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
                                                                                     at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
                                                                                     at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
                                                                                     at android.view.View.measure(View.java:17826)
                                                                                     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5653)
                                                                                     at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
                                                                                     at android.view.View.measure(View.java:17826)
                                                                                     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5653)
                                                                                     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
                                                                                     at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
                                                                                     at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
                                                                                     at android.view.View.measure(View.java:17826)
                                                                                     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5653)
                                                                                     at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
                                                                                     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2748)
                                                                                     at android.view.View.measure(View.java:17826)
                                                                                     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2030)
                                                                                     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1174)
                                                                                     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1395)
                                                                                     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1062)
                                                                                     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5873)
                                                                                     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
                                                                                     at android.view.Choreographer.doCallbacks(Choreographer.java:580)
                                                                                     at android.view.Choreographer.doFrame(Choreographer.java:550)
                                                                                     at android.view.Choreographer$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:5536)
                                                                                     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:1397)
                                                                                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.j
03-19 18:00:57.404 28193-28193/com.android.example I/Process: Sending signal. PID: 28193 SIG: 9

Answer 1

我认为你应该将 inflater.inflate() 的结果传递给 initUI()。不确定，但我认为 getView() 返回 null 是因为系统还没有收到您新创建的 View (您刚刚创建了它，但只有从 onCreateView 返回后才会绑定(bind)到 fragment )。