我试图调用从另一个类中的方法,但我得到一个异常错误。
I am trying to call a method from another class but I get an exception error.
我有两个阶级和阶级1是主类
I have two classes and class 1 is the main class
1类有一个的onclick
方法,它从另一个类调用方法的onclick
。
Class 1 has an onclick
method which calls the method from another class onclick
.
我有文本框和edittexts在声明的类1。
I have textfields and edittexts declared in class 1.
2类具有这些功能,并使用if语句。
Class 2 has functionality for these and uses if statements.
我从第2类扩展类1所以2级使用的变量。
I extend class 1 from class 2 so class 2 uses the variables.
哪些方面,我还可以从其他类中的方法在机器人。
What are the ways I can call methods from other classes in android.
目前,我只是用中调用类2类1的方法:
At the moment I just call the method from class 2 in class 1 by using:
class1.method();
但这似乎并不奏效。鸭preciate任何意见表示感谢。
but this doesn't seem to be working. Appreciate any advice thanks.
编辑:
我现在已经在1级创建一个变量:
I have now created in class 1 a variable:
static class2 object;
这是在这个我称之为的onclick
:
object.class2method();
我得到一个NullPointerException异常错误的感谢。
I get a nullPointerexception error thanks.
如果我正确地理解你的问题,如果你要调用一个扩展类的方法,你需要确保这些方法是公共或受保护
If I've understood your question correctly, if you want to call the methods in a extended class, you need to make sure those methods are either public or protected.
还省略了类名,比如就叫办法()
不是 class.method()
Also omit the classname, eg just call method()
not class.method()
只是为了阐述这个更多一些,这里是一些code我刚熟了:
Just to elaborate on this some more, here is some code I just cooked up:
class class1 {
private void privateMethod() {
// do nothing
}
protected void protectedMethod() {
// do nothing
}
public void publicMethod() {
// do nothing
}
}
class class2 extends class1 {
private void testMethod() {
privateMethod(); // error - not visible
protectedMethod(); // works
publicMethod(); // also works
}
}