我的主要 Activity 中有两个来自 Runner 的线程,并通过单击按钮启动它们。你唯一要做的就是数数。我想用 ech 线程的当前计数更新两个 TextView。当我启动应用程序并单击按钮时,应用程序崩溃了。
代码在控制台中完美运行。
Runner类仅用于计数。我想在方法 running() 中的每个段落之后更新两个 TextView。
public class Runner extends Activity implements Runnable {
int count = 0;
String name;
public Runner(String name) {
super();
this.name = name;
}
public void warten() throws InterruptedException {
int zahl = (int) (Math.random() * 500) + 500;
Thread.sleep(zahl);
}
public void running() throws InterruptedException {
for(int i = 0; i < 10; i++) {
warten();
count++;
System.out.println(name + " ist bei: " + count);
if(count == 10) {
System.out.println(name + " IST FERTIG");
}
runOnUiThread(new UiThread(name, count));
}
}
public void run() {
try {
running();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
UiThread 类应该是更新 UI 的主线程。
public class UiThread extends Activity implements Runnable {
String name;
int count;
TextView textView1;
TextView textView2;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
textView1 = findViewById(R.id.textView2);
textView2 = findViewById(R.id.textView3);
}
public UiThread(String name, int count){
this.name = name;
this.count = count;
}
@Override
public void run() {
if(name == "thread1"){
textView1.setText("thread1 ist bei: " + count);
}else{
textView2.setText("thread2 ist bei: " + count);
}
}
}
最佳答案
我建议您查看本关于 Android 线程的指南 docs .
您无法初始化 Activity 类,只能将其添加到 list 中,这样做会导致上下文为空。因此,请删除 UiThread 类中的构造函数。
此外,您不需要您的运行者类来扩展 Activity。传递 Activity 的实例以便使用 runOnUiThread() 方法。
下面是 UiTHread 类应该是什么样子的示例。
public class UiThread extends Activity {
public TextView textView1;
public TextView textView2;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
textView1 = findViewById(R.id.textView2);
textView2 = findViewById(R.id.textView3);
startThreads();
}
private void startThreads(){
// Initialize the runnable class passing this activity context.
Runner runner = new Runner(this);
Thread thread1 = new Thread(runner, "thread1");
Thread thread2 = new Thread(runner, "thread2");
thread1.start();
thread2.start();
}
}
运行者类别
public class Runner implements Runnable {
private int count = 0;
private UiThread context;
public Runner(UiThread activityContext) {
this.context = activityContext;
}
public void warten() throws InterruptedException {
int zahl = (int) (Math.random() * 500) + 500;
Thread.sleep(zahl);
}
public void running() throws InterruptedException {
for(int i = 0; i < 10; i++) {
warten();
count++;
System.out.println(Thread.currentThread().getName() + " ist bei: " + count);
if(count == 10) {
System.out.println(Thread.currentThread().getName() + " IST FERTIG");
}
// update text views from the main thread.
context.runOnUiThread(new Runnable() {
@Override
public void run() {
if(Thread.currentThread().getName().equals("thread1")){
context.textView1.setText("thread1 ist bei: " + count);
}else{
context.textView2.setText("thread2 ist bei: " + count);
}
}
});
}
}
public void run() {
try {
running();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
希望这有帮助。
关于java - 如何使用 runOnUiThread 更新 TextView,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/62234856/