Androidx Null指针异常错误,Invoke方法

问题描述 投票:-1回答:1

我收到了这个错误。这是我的logcat。我不知道到底出了什么问题。我得到撤销错误或我们可以说NullExceptionError。我尝试了一切,但没有锻炼。

 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.RelativeLayout.setVisibility(int)' on a null object reference
    at com.nazeefawann.truemate.Profile.AccountSettingActivity.setViewPager(AccountSettingActivity.java:52)
    at com.nazeefawann.truemate.Profile.AccountSettingActivity$2.onItemClick(AccountSettingActivity.java:71)
    at android.widget.AdapterView.performItemClick(AdapterView.java:303)
    at android.widget.AbsListView.performItemClick(AbsListView.java:1151)
    at android.widget.AbsListView$PerformClick.run(AbsListView.java:3065)
    at android.widget.AbsListView$3.run(AbsListView.java:3878)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:135)
    at android.app.ActivityThread.main(ActivityThread.java:5538)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller
    .run(ZygoteInit.java:960)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

我正在制作一个应用程序,我想在设置活动中制作片段而不是分开,以便我可以轻松添加更多功能。我创建了2片段,但是当我点击它时返回上一个活动。我不知道为什么

public void setViewPager(int fragmentNumbers){
    mRelativeLayout.setVisibility(View.GONE);
    Log.d(TAG,"setViewPager: navigating to fragment #:" + fragmentNumbers);
    viewPager.setAdapter(pagerAdapter);
    viewPager.setCurrentItem(fragmentNumbers); 

这是我的AccountSettingActivity

 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.viewpager.widget.ViewPager;

public class AccountSettingActivity extends AppCompatActivity {
private Context mContext;
private SectionStatePagerAdapter pagerAdapter;
private ViewPager viewPager;
private RelativeLayout mRelativeLayout;
private String TAG;

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    viewPager = (ViewPager) findViewById(R.id.container);
    mRelativeLayout = (RelativeLayout) findViewById(R.id.relaytiveLayout11);
    mContext = AccountSettingActivity.this;
    setContentView(R.layout.activity_accountsettings);
    setupSettingList();
    setupFragment();
    ImageView backArrow = (ImageView) findViewById(R.id.backArrow);
    backArrow.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            finish();
        }
    });
}
private void setupFragment(){
    pagerAdapter = new SectionStatePagerAdapter(getSupportFragmentManager());
    pagerAdapter.addFragment(new EditProfileFragment(), getString(R.string.edit_profile_fragment)); //fragment 0
    pagerAdapter.addFragment(new SignOutFragment(), getString(R.string.sign_out_fragment)); //fragment 1
}
public void setViewPager(int fragmentNumbers){
    mRelativeLayout.setVisibility(View.GONE);
    Log.d(TAG,"setViewPager: navigating to fragment #:" + fragmentNumbers);
    viewPager.setAdapter(pagerAdapter);
    viewPager.setCurrentItem(fragmentNumbers);

}
private void setupSettingList(){
    ListView listView = (ListView) findViewById(R.id.lvAccountSettings);

    ArrayList<String> options = new ArrayList<>();
    options.add(getString(R.string.edit_profile_fragment)); //fragment 0
    options.add(getString(R.string.sign_out_fragment)); //fragement 1

    ArrayAdapter adapter = new ArrayAdapter(mContext, android.R.layout.simple_list_item_1, options);
    listView.setAdapter(adapter);

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            setViewPager(position);
        }
    });

}

}

这是我的xml文件

<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">

<include layout="@layout/layout_center_viewpager"></include>
<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/relaytiveLayout11">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/relLayout2">
        <include layout="@layout/snippet_top_settingtoolbar"/>

    </RelativeLayout>
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/relLayout3"
        android:layout_below="@id/relLayout2"
        android:layout_marginBottom="50dp">

        <include layout="@layout/layout_center_accountsettiings"/>

    </RelativeLayout>


</RelativeLayout>

我正在使用android x库,因为这个库我可能会收到错误

我无法在此代码中找到错误我做了很多实验,但没有任何结果我相信你们中的一些人会帮助我感谢提前

android listview android-viewpager adapter android-relativelayout
1个回答
0
投票

在打电话给findViewById之前,不要打电话给任何mRelativeLayout = (RelativeLayout) findViewById(R.id.relaytiveLayout11);,即setContentView。确保在访问任何视图之前调用它。

像这样重新调整你的代码



    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mContext = AccountSettingActivity.this;
        setContentView(R.layout.activity_accountsettings);
        viewPager = (ViewPager) findViewById(R.id.container);
        mRelativeLayout = (RelativeLayout) findViewById(R.id.relaytiveLayout11);
        setupSettingList();
        setupFragment();
        ImageView backArrow = (ImageView) findViewById(R.id.backArrow);
        backArrow.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                finish();
            }
        });
    }

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