Question

我想要一个Android应用程序，只要我按下按钮，背景就会闪烁。这有效，但是当我释放按钮时，背景不会停止闪烁。我认为原因是我使用的是Thread。我不确切知道如何阻止它（我第一次使用Threads工作）。我以为我可以在按钮“threadname.stop（）”的Action_Up事件中写，但Android工作室无法解析名称。那么：我如何停止线程以便执行Action_Up案例？非常感谢!!!

我的主要活动代码：

import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.RelativeLayout;

public class MainActivity extends AppCompatActivity {

    Button flash;
    RelativeLayout layout;
    boolean backgroundisblack;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        backgroundisblack = true;
        layout = (RelativeLayout)findViewById(R.id.layout);
        flash = (Button)findViewById(R.id.flash );

        //Button
        flash.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {


                //button is pressed
                switch (event.getAction()){
                    case MotionEvent.ACTION_DOWN:{

                        //thread
                        Thread t = new Thread(){
                            @Override
                            public void run(){
                                while(!interrupted()){
                                    try {
                                        Thread.sleep(1000);

                                        runOnUiThread(new Runnable(){
                                            @Override
                                            public void run(){
                                               //action
                                                if(backgroundisblack){
                                                    layout.setBackgroundColor(Color.WHITE);
                                                    backgroundisblack = false;
                                                }else if (!backgroundisblack){
                                                    layout.setBackgroundColor(Color.BLACK);
                                                    backgroundisblack = true;
                                                }



                                            }
                                        });
                                    }catch (InterruptedException e){
                                        e.printStackTrace();
                                    }
                                }
                            }
                        };
                        t.start();


                        break;
                    }

                    //button is released
                    case MotionEvent.ACTION_UP:{
                        layout.setBackgroundColor(Color.BLACK);

                        break;
                    }
                }
                return false;
            }
        });


    }
}

Answer 1

添加字段needToRun默认为true。继续while循环，同时：！中断（）及;＆安培; needToRun。检测TOUCH_UP时将needToRun设置为false。这是一种在java中停止线程的推荐方法。

Answer 2

设置布尔字段

private boolean runningThread;

然后将run方法更改为：

public void run(){
    runningThread = true;
    while( runningThread ){
    // ...

并在发布时：

 case MotionEvent.ACTION_UP:{
    runningThread = false; 
    // ...

Answer 3

从案例MotionEvent.ACTION_UP中访问您的主题这样做在全局范围内定义线程t
将t.interrupt（）添加到案例MotionEvent.ACTION_UP

它看起来像

import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.RelativeLayout;

public class MainActivity extends AppCompatActivity {

Button flash;
RelativeLayout layout;
boolean backgroundisblack;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    backgroundisblack = true;
    layout = (RelativeLayout)findViewById(R.id.layout);
    flash = (Button)findViewById(R.id.flash );
    //Button
    flash.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            Thread t;
            //button is pressed
            switch (event.getAction()){
                case MotionEvent.ACTION_DOWN:{//thread
                    t = new Thread(){
                        @Override
                        public void run(){
                            while(!interrupted()){
                                try {
                                    Thread.sleep(1000);
                                    runOnUiThread(new Runnable(){
                                        @Override
                                        public void run(){
                                           //action
                                            if(backgroundisblack){
                                                layout.setBackgroundColor(Color.WHITE);
                                                backgroundisblack = false;
                                            }else if (!backgroundisblack){
                                                layout.setBackgroundColor(Color.BLACK);
                                                backgroundisblack = true;
                                            }



                                        }
                                    });
                                }catch (InterruptedException e){
                                    e.printStackTrace();
                                }
                            }
                        }
                    };
                    t.start();


                    break;
                }

                //button is released
                case MotionEvent.ACTION_UP:{
                    layout.setBackgroundColor(Color.BLACK);
                    t.interrupt()
                    break;
                }
            }
            return false;
        }
    });

}
}

Answer 4

你可以在按下时按下按钮以及释放时再添加一个条件

// this goes somewhere in your class:
  long lastDown;
  long lastDuration;

  ...

  // this goes wherever you setup your button listener:
  button.setOnTouchListener(new OnTouchListener() {
     @Override
     public boolean onTouch(View v, MotionEvent event) {
        if(event.getAction() == MotionEvent.ACTION_DOWN) {
           lastDown = System.currentTimeMillis();
        } else if (event.getAction() == MotionEvent.ACTION_UP) {
           lastDuration = System.currentTimeMillis() - lastDown;
        }
     }
  });

因此可以使用thread.interrupt（）来停止线程。

如果不再按下按钮，我该如何停止线程？

4 个答案: