Question

我正在制作app手电筒.....但我想要停止闪烁的led手电筒......这是我的代码，但我无法阻止我闪烁的手电筒..

String  myString = "010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101011";
long blinkDelay = 50;

for (int i = 0; i < myString.length(); i++) {
    if (myString.charAt(i) == '0') {
        p.setFlashMode(Parameters.FLASH_MODE_TORCH);
        cam.setParameters(p);
    }
    else {
        p.setFlashMode(Parameters.FLASH_MODE_OFF);
        cam.setParameters(p);
    }
    Thread.sleep(blinkDelay);
}
}catch (Exception e) {
}

Answer 1

您需要考虑线程安全性，因为运行此循环的代码应位于单独的线程上。将boolean设置为安全停止至少需要AtomicBoolean，但更容易使用不同的技术，AsyncTask已经可以取消，并且不需要您创建和直接管理新线程：

package com.stackoverflow.blinker;

import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.os.AsyncTask;

public final class Blinker extends AsyncTask<Void, Void, Void> {

    private final long blinkDelay = 50;
    private final Camera cam;
    private boolean on;

    public Blinker(Camera cam) {
        this.cam = cam;
    }

    @Override
    protected Void doInBackground(Void... params) {
        while (!isCancelled()) {
            toggleLight();
            try {
                wait(getBlinkDelay());
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                break;
            }
        }
        setFinalLightState();
        return null;
    }

    private void setFinalLightState() {
        // optionally turn off at the end
        setOn(false);
    }

    private long getBlinkDelay() {
        // want to have light on for a different time to it is off? do this:
        // return isOn() ? blinkDelayOn : blinkDelayOff;
        return blinkDelay;
    }

    private void toggleLight() {
        setOn(!isOn());
    }

    public boolean isOn() {
        return on;
    }

    public void setOn(boolean on) {
        this.on = on;
        Camera.Parameters p = cam.getParameters();
        if (on) {
            p.setFlashMode(Parameters.FLASH_MODE_TORCH);
        } else {
            p.setFlashMode(Parameters.FLASH_MODE_OFF);
        }
        cam.setParameters(p);
    }
}

用法：

//create
Blinker b = new Blinker(Camera.open());
//start
b.execute();
//stop
b.cancel(false);

Answer 2

在你的for循环中创造一个条件。

例如，创建一个类的私有变量：

boolean stop = false;

在循环中检查：

for (int i = 0; (i < myString.length()) && !stop; i++) {
   ....
}

代码中的某处：

stop = true;

如何在Android中停止我们闪烁的手电筒

2 个答案: