Question

Android Studio 3.1，Java 1.8，Gradle 4.1。我使用minVersion = 15

我想在文件profile_category_active.xml中以编程方式设置GridConstrainLayout的宽度。所以......

这是我的主要XML

<android.support.constraint.ConstraintLayout
       android:id="@+id/categoriesContainer"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       app:layout_constraintEnd_toEndOf="parent"
       app:layout_constraintStart_toStartOf="@+id/nameContainer"
       app:layout_constraintTop_toBottomOf="@+id/birthDateContainer">

       <GridLayout
            android:id="@+id/categoriesGridContainer"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@color/place_holder_color"
            app:layout_constraintEnd_toEndOf="@+id/categoriesContainer"
            app:layout_constraintStart_toStartOf="@+id/categoriesContainer"
            app:layout_constraintTop_toBottomOf="@+id/categoriesContainer" />

</android.support.constraint.ConstraintLayout>

此处 profile_category_active.xml ：

<android.support.constraint.ConstraintLayout     
     xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/profileCategoryContainer"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/profile_category_active_bg">


    <TextView
        android:id="@+id/categoryNameTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="5dp"
        android:layout_marginEnd="10dp"
        android:layout_marginLeft="5dp"
        android:layout_marginRight="10dp"
        android:layout_marginStart="5dp"
        android:layout_marginTop="5dp"
        android:ellipsize="end"
        android:maxLines="1"
        android:text="TextView"
        android:textColor="#292929"
        android:textSize="15sp"/>
</android.support.constraint.ConstraintLayout>

这里有活动代码：

public class ProfileActivity extends AppCompatActivity {
    private static final String TAG = ProfileActivity.class.getName();

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ProfileBinding profileBinding = DataBindingUtil.setContentView(this, R.layout.profile);
        GridLayout categoriesGridContainer = findViewById(R.id.categoriesGridContainer);
        categoriesGridContainer.setColumnCount(columnCount);
        LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        for (int index = 0; index < 13; index++) {
            View profileCategoryActive = inflater.inflate(R.layout.profile_category_active, null, false);
            categoriesGridContainer.addView(profileCategoryActive);
            ConstraintLayout profileCategoryContainer = profileCategoryActive.findViewById(R.id.profileCategoryContainer);
            ConstraintLayout.LayoutParams profileCategoryContaineParams = (ConstraintLayout.LayoutParams) profileCategoryContainer.getLayoutParams();
            profileCategoryContaineParams.width = (int) AndroidUtil.dpToPx(this, categoryItemWidth);                
        }
    }
 }

但是在运行时我得到错误：

FATAL EXCEPTION: main
Process: com.myproject.android.customer.debug, PID: 15496
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myproject.android.customer.debug/com.myproject.android.customer.ui.ProfileActivity}: java.lang.ClassCastException: android.widget.GridLayout$LayoutParams cannot be cast to android.support.constraint.ConstraintLayout$LayoutParams
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
    at android.app.ActivityThread.-wrap11(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.ClassCastException: android.widget.GridLayout$LayoutParams cannot be cast to android.support.constraint.ConstraintLayout$LayoutParams
    at com.myproject.android.customer.ui.ProfileActivity.init(ProfileActivity.java:76)

为什么这行错误？

   ConstraintLayout.LayoutParams profileCategoryContaineParams = (ConstraintLayout.LayoutParams) profileCategoryContainer.getLayoutParams();

profileCategoryContainer是ConstraintLayout（不是GridLayout）

Answer 1

试试这个

ConstraintLayout.LayoutParams clpcontactUs = new ConstraintLayout.LayoutParams(
       ConstraintLayout.LayoutParams.WRAP_CONTENT, ConstraintLayout.LayoutParams.WRAP_CONTENT);
contactUs.setLayoutParams(clpcontactUs);

GridLayout $ LayoutParams无法强制转换为android.support.constraint.ConstraintLayout $ LayoutParams

1 个答案: