android – 动态地将视图添加到特定的片段布局中

我试图动态地将TextView添加到作为片段的一部分的布局中,但它不起作用.应用程序启动后立即关闭.
我认为它必须做一些事情
TextView Paper = new TextView(this);部分.因为我正在使用Fragments,所以我不知道如何获得正确的上下文.也许我的假设是错误的,但我真的不知道错误可能在哪里.

public class PageFragment extends Fragment {
 
    private int fragmentNR;
 
    public PageFragment(int nr) {
        this.fragmentNR = nr;
    }
 
    @Override
    public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
        View v = new View(getActivity());
        if (fragmentNR == 0)
            v = inflater.inflate(R.layout.page1,container,false);
        else if (fragmentNR == 1)
            v = inflater.inflate(R.layout.page2,false);
        else if (fragmentNR == 2)
            v = inflater.inflate(R.layout.page3,false);
 
        return v;
    }
 
}

06001

logcat的

07-18 16:32:58.330: E/AndroidRuntime(614): FATAL EXCEPTION: main
07-18 16:32:58.330: E/AndroidRuntime(614): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.loni.math_prime/com.loni.math_prime.MainActivity}: java.lang.NullPointerException
07-18 16:32:58.330: E/AndroidRuntime(614):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
07-18 16:32:58.330: E/AndroidRuntime(614):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
07-18 16:32:58.330: E/AndroidRuntime(614):  at android.app.ActivityThread.access$600(ActivityThread.java:130)
07-18 16:32:58.330: E/AndroidRuntime(614):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
07-18 16:32:58.330: E/AndroidRuntime(614):  at android.os.Handler.dispatchMessage(Handler.java:99)
07-18 16:32:58.330: E/AndroidRuntime(614):  at android.os.Looper.loop(Looper.java:137)
07-18 16:32:58.330: E/AndroidRuntime(614):  at android.app.ActivityThread.main(ActivityThread.java:4745)
07-18 16:32:58.330: E/AndroidRuntime(614):  at java.lang.reflect.Method.invokeNative(Native Method)
07-18 16:32:58.330: E/AndroidRuntime(614):  at java.lang.reflect.Method.invoke(Method.java:511)
07-18 16:32:58.330: E/AndroidRuntime(614):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
07-18 16:32:58.330: E/AndroidRuntime(614):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
07-18 16:32:58.330: E/AndroidRuntime(614):  at dalvik.system.NativeStart.main(Native Method)
07-18 16:32:58.330: E/AndroidRuntime(614): Caused by: java.lang.NullPointerException
07-18 16:32:58.330: E/AndroidRuntime(614):  at com.loni.math_prime.MainActivity.onCreate(MainActivity.java:30)
07-18 16:32:58.330: E/AndroidRuntime(614):  at android.app.Activity.performCreate(Activity.java:5008)
07-18 16:32:58.330: E/AndroidRuntime(614):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
07-18 16:32:58.330: E/AndroidRuntime(614):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
07-18 16:32:58.330: E/AndroidRuntime(614):  ... 11 more

XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
     >
 
    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" >
 
        <android.support.v4.view.PagerTitleStrip
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:textSize="32dp"
            android:textStyle="bold"
            android:textColor="#fff5ee"
            android:layout_gravity="top" />
    </android.support.v4.view.ViewPager>
 
</LinearLayout>

解决方法

解决了：

public class PageFragment extends Fragment {
 
private int fragmentNR;
 
 
public PageFragment(int nr) {
    this.fragmentNR = nr;
}
 
@Override
public View onCreateView(LayoutInflater inflater,Bundle savedInstanceState) {
 
    View v = new View(getActivity());
 
    if (fragmentNR == 0)
        v = inflater.inflate(R.layout.page1,false);
    else if (fragmentNR == 1){
        v = inflater.inflate(R.layout.page2,false);
        View tv = v.findViewById(R.id.Ausgabe);
        ((TextView)tv).setText("TestText");
        View pl = v.findViewById(R.id.PageLayout);
        TextView Paper = new TextView(pl.getContext());
        Paper.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));
        Paper.setText("Inserted TestText");
        ((LinearLayout)pl).addView(Paper);
        }
    else if (fragmentNR == 2)
        v = inflater.inflate(R.layout.page3,false);
 
    return v;
}
}

android – 动态地将视图添加到特定的片段布局中

解决方法

猜你在找的Android相关文章