Question

我有一个java文件和一个活动类文件。在活动类中我有一个Textview。如何从我的java类

更改textview文本

public void sendMessageforstatus(String status)
{
        if(status.contains("Door is open"))
        {

                ds.updatedoor("open");

        }

        else if(status.equalsIgnoreCase("Door is close"))
        {
               ds.updatedoor("close");

        }
}

这是java文件中的逻辑，现在我想更新Textview中另一个活动类的文本

public void sendMessageforstatus(String status)
{
    if(status.contains("Door is open"))
    {


        tdoor.setText("OPEN");
    }

    else if(status.equalsIgnoreCase("Door is close"))
    {

        tdoor.setText("CLOSE");
    }

这是活动类中的代码方法，但是当我尝试这个时，我得到的是NULLpointerException ...

你可以帮助我吗？

Answer 1

使textview摘要并从java类中尝试此代码

activityname.textviewname.setText("blahblah");

Answer 2

将import it.unimi.dsi.fastutil.ints.IntArrayList import it.unimi.dsi.fastutil.chars.CharArrayList import it.unimi.dsi.fastutil.objects.ObjectArrayList class Container[@specialized(Int,Char) T](window: Int)(implicit impl: ContainerImpl[T]) { impl.init(window) def add(element: T) = impl.add(element) override def toString = impl.toString } trait ContainerImpl[@specialized(Int,Char) T] { def init(window: Int): Unit def add(element: T): Unit def toString: String } object ContainerImpl extends LowerPriorityImplicits { implicit def intContainer = new ContainerImplInt implicit def charContainer = new ContainerImplChar } trait LowerPriorityImplicits { implicit def anyContainer[T] = new ContainerImplT[T] } final class ContainerImplInt extends ContainerImpl[Int] { var data: IntArrayList = _ def init(window: Int) = data = new IntArrayList(window) def add(element: Int) = data.add(element) override def toString = data.toString } final class ContainerImplChar extends ContainerImpl[Char] { var data: CharArrayList = _ def init(window: Int) = data = new CharArrayList(window) def add(element: Char) = data.add(element) override def toString = data.toString } final class ContainerImplT[T] extends ContainerImpl[T] { var data: ObjectArrayList[T] = _ def init(window: Int) = data = new ObjectArrayList(window) def add(element: T) = data.add(element) override def toString = data.toString }传递给您的Java类，然后您可以在其中使用它。

活动类和java类之间的通信

2 个答案: