有人能告诉我如何将参数传递给线程吗?
另外,匿名类是如何工作的?
有人能告诉我如何将参数传递给线程吗?
另外,匿名类是如何工作的?
当前回答
你需要在构造函数中将参数传递给Runnable对象:
public class MyRunnable implements Runnable {
public MyRunnable(Object parameter) {
// store parameter for later user
}
public void run() {
}
}
并这样调用它:
Runnable r = new MyRunnable(param_value);
new Thread(r).start();
其他回答
您可以扩展Thread类或Runnable类,并根据需要提供参数。文档中有一些简单的例子。我将把它们移植到这里:
class PrimeThread extends Thread {
long minPrime;
PrimeThread(long minPrime) {
this.minPrime = minPrime;
}
public void run() {
// compute primes larger than minPrime
. . .
}
}
PrimeThread p = new PrimeThread(143);
p.start();
class PrimeRun implements Runnable {
long minPrime;
PrimeRun(long minPrime) {
this.minPrime = minPrime;
}
public void run() {
// compute primes larger than minPrime
. . .
}
}
PrimeRun p = new PrimeRun(143);
new Thread(p).start();
通过Runnable或Thread类的构造函数
class MyThread extends Thread {
private String to;
public MyThread(String to) {
this.to = to;
}
@Override
public void run() {
System.out.println("hello " + to);
}
}
public static void main(String[] args) {
new MyThread("world!").start();
}
这个答案来得很晚,但也许有人会觉得它有用。它是关于如何在不声明命名类的情况下将参数传递给Runnable(对于内联程序来说很方便):
String someValue = "Just a demo, really...";
new Thread(new Runnable() {
private String myParam;
public Runnable init(String myParam) {
this.myParam = myParam;
return this;
}
@Override
public void run() {
System.out.println("This is called from another thread.");
System.out.println(this.myParam);
}
}.init(someValue)).start();
当然,您可以将start的执行推迟到某个更方便或合适的时刻。这取决于你init方法的签名(所以它可能需要更多和/或不同的参数),当然甚至它的名字,但基本上你得到了一个想法。
事实上,还有另一种将参数传递给匿名类的方法,即使用初始化块。考虑一下:
String someValue = "Another demo, no serious thing...";
int anotherValue = 42;
new Thread(new Runnable() {
private String myParam;
private int myOtherParam;
// instance initializer
{
this.myParam = someValue;
this.myOtherParam = anotherValue;
}
@Override
public void run() {
System.out.println("This comes from another thread.");
System.out.println(this.myParam + ", " + this.myOtherParam);
}
}).start();
所有都发生在初始化程序块内部。
你需要在构造函数中将参数传递给Runnable对象:
public class MyRunnable implements Runnable {
public MyRunnable(Object parameter) {
// store parameter for later user
}
public void run() {
}
}
并这样调用它:
Runnable r = new MyRunnable(param_value);
new Thread(r).start();
Android专用
为了回调的目的,我通常使用输入参数实现自己的泛型Runnable:
public interface Runnable<TResult> {
void run(TResult result);
}
用法很简单:
myManager.doCallbackOperation(new Runnable<MyResult>() {
@Override
public void run(MyResult result) {
// do something with the result
}
});
在经理:
public void doCallbackOperation(Runnable<MyResult> runnable) {
new AsyncTask<Void, Void, MyResult>() {
@Override
protected MyResult doInBackground(Void... params) {
// do background operation
return new MyResult(); // return resulting object
}
@Override
protected void onPostExecute(MyResult result) {
// execute runnable passing the result when operation has finished
runnable.run(result);
}
}.execute();
}