Question

我的问题：我实际上想要随机设置我的ImageView的可见性。我的意思是每个图像视图将在几毫秒后随机可见，但我的应用程序意外地一直崩溃。虽然，我是Android开发新手，但擅长Java J2SE。请告诉我我在做什么是偶然的错误或错误？请！提前谢谢！

 package com.example.app;

 import java.util.Random;
 import android.os.Bundle;
 import android.app.Activity;
 import android.view.Menu;
 import android.view.View;
 import android.widget.Button;
 import android.widget.ImageView;
 import android.widget.TextView;

public class MainActivity extends Activity {
private Button b;
public ImageView I1;
public ImageView I2;
public ImageView I3;
public ImageView I4;
public TextView T;
public TextView s;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

     I1=new ImageView(this);
     I1=(ImageView) findViewById(R.id.imag1);
     I1.setVisibility(View.INVISIBLE);

     I2=new ImageView(this);
     I2=(ImageView) findViewById(R.id.imag2);
     I2.setVisibility(View.INVISIBLE);

     I3=new ImageView(this);
     I3=(ImageView) findViewById(R.id.imag3);
     I3.setVisibility(View.INVISIBLE);

     I4=new ImageView(this);
     I4=(ImageView) findViewById(R.id.imag4);
     I4.setVisibility(View.INVISIBLE);

     T=(TextView)findViewById(R.id.time);
     s=(TextView)findViewById(R.id.score);

    Thread t=new Thread(new MyThread());
    t.start();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

private class MyThread implements Runnable{
    Random randomGenerator = new Random();
    int n;
    public void run(){

        while(true){
            n=randomGenerator.nextInt(8);

            if(n==1){
                I1.setVisibility(View.VISIBLE);

            }
            if(n==2){
                I2.setVisibility(View.VISIBLE);
            }

            if(n==3){
                I3.setVisibility(View.VISIBLE);
            }

            if(n==4){
                I4.setVisibility(View.VISIBLE);
            }
            try {
                Thread.currentThread().sleep(500);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                 e.getStackTrace();
            }
        }

    }




}
}

编辑代码：

  public ImageView I1;
  public ImageView I2;
  public ImageView I3;
  public ImageView I4;
  public TextView T;
  public TextView s;
  Random randomGenerator = new Random();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

     I1=new ImageView(this);
     I1=(ImageView) findViewById(R.id.imag1);
     I1.setVisibility(View.INVISIBLE);

     I2=new ImageView(this);
     I2=(ImageView) findViewById(R.id.imag2);
    I2.setVisibility(View.INVISIBLE);

     I3=new ImageView(this);
     I3=(ImageView) findViewById(R.id.imag3);
    I3.setVisibility(View.INVISIBLE);

     I4=new ImageView(this);
     I4=(ImageView) findViewById(R.id.imag4);
     I4.setVisibility(View.INVISIBLE);

     T=(TextView)findViewById(R.id.time);
     s=(TextView)findViewById(R.id.score);


     runOnUiThread(new Runnable() //run on ui thread
      {
         int n;
           public void run(){ 
               while(true){

                n=randomGenerator.nextInt(4)+1;

                if(n==1){
                    I1.setVisibility(View.VISIBLE);

                }
                if(n==2){
                    I2.setVisibility(View.VISIBLE);
                }

                if(n==3){
                    I3.setVisibility(View.VISIBLE);
                }

                if(n==4){
                    I4.setVisibility(View.VISIBLE);
                }

            }
           }
       });
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

Answer 1

android.view.ViewRootImpl $ CalledFromWrongThreadException：只有创建视图层次结构的原始线程才能触及其视图。

您必须如上所述获得例外。您需要在UI线程上更新ui。您正在更新线程中的UI。因此异常和崩溃。

在你的线程中使用runOnUiThread来更新UI

      runOnUiThread(new Runnable() //run on ui thread
      {
           public void run() 
           { 
                 while(true){
                 n=randomGenerator.nextInt(8);

                 if(n==1){
                  I1.setVisibility(View.VISIBLE);
                 }
                 ....
                 }
           }
       });

同时删除此I1 = new ImageView（this）;因为你正在初始化为I1 =（ImageView）findViewById（R.id.imag1）;

编辑：

我建议使用Handler来实现此目的

        int n;
    Handler m_handler;
    Runnable m_handlerTask ; 
    Random r;

将上述声明为类变量;

在活动onCrate（）内部使用如下处理程序

          r= new Random();
        m_handler= new Handler();
        m_handlerTask = new Runnable()
        {
             @Override 
             public void run() {
                 n=r.nextInt(4)+1;
                    if(n==1){
                        I1.setVisibility(View.VISIBLE);
                        I2.setVisibility(View.INVISIBLE);
                        I3.setVisibility(View.INVISIBLE);
                        I4.setVisibility(View.INVISIBLE);

                    }
                    if(n==2){
                        I2.setVisibility(View.VISIBLE);
                        I1.setVisibility(View.INVISIBLE);
                        I3.setVisibility(View.INVISIBLE);
                        I4.setVisibility(View.INVISIBLE); 
                    }

                    if(n==3){
                        I3.setVisibility(View.VISIBLE);
                        I1.setVisibility(View.INVISIBLE);
                        I2.setVisibility(View.INVISIBLE);
                        I4.setVisibility(View.INVISIBLE); 
                    }

                    if(n==4){
                        I4.setVisibility(View.VISIBLE);
                        I1.setVisibility(View.INVISIBLE);
                        I3.setVisibility(View.INVISIBLE);
                        I2.setVisibility(View.INVISIBLE); 
                    }
                  m_handler.postDelayed(m_handlerTask, 50);
                      // 50 milli seconds. set this to desired number
             }
        };
        m_handlerTask.run();

请记住在不需要时停止处理程序

          m_handler.removeCallbacks(m_handlerTask);

Answer 2

我想你想要完整的代码。你可以使用计时器。请参阅以下代码。

public class MainActivity extends Activity {

public ImageView I1;
public ImageView I2;
public ImageView I3;
public ImageView I4;
public TextView T;
public TextView s;
int n;
Timer t;
TimerTask task;

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

    I1 = (ImageView) findViewById(R.id.imag1);
    I1.setVisibility(View.INVISIBLE);

    I2 = (ImageView) findViewById(R.id.imag2);
    I2.setVisibility(View.INVISIBLE);

    I3 = (ImageView) findViewById(R.id.imag3);
    I3.setVisibility(View.INVISIBLE);

    I4 = (ImageView) findViewById(R.id.imag4);
    I4.setVisibility(View.INVISIBLE);

    T = (TextView) findViewById(R.id.time);
    s = (TextView) findViewById(R.id.score);
    startTimer();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

public void startTimer() {
    //Random randomGenerator = new Random();
    //n=randomGenerator.nextInt(8);
            final Random randomGenerator = new Random();

    t = new Timer();
    task = new TimerTask() { 

        @Override
        public void run() {
            runOnUiThread(new Runnable() {

                public void run() {
                    //n++;
                                            n=randomGenerator.nextInt(8);
                    if (n == 1) {
                        I1.setVisibility(View.VISIBLE);
                                                    I2.setVisibility(View.INVISIBLE);
                                                    I3.setVisibility(View.INVISIBLE);
                                                    I4.setVisibility(View.INVISIBLE);

                    }
                    if (n == 2) {
                        I1.setVisibility(View.INVISIBLE);
                                                    I2.setVisibility(View.VISIBLE);
                                                    I3.setVisibility(View.INVISIBLE);
                                                    I4.setVisibility(View.INVISIBLE);
                    }

                    if (n == 3) {
                        I1.setVisibility(View.INVISIBLE);
                                                    I2.setVisibility(View.INVISIBLE);
                                                    I3.setVisibility(View.VISIBLE);
                                                    I4.setVisibility(View.INVISIBLE);
                    }

                    if (n == 4) {
                        I1.setVisibility(View.INVISIBLE);
                                                    I2.setVisibility(View.INVISIBLE);
                                                    I3.setVisibility(View.INVISIBLE);
                                                    I4.setVisibility(View.VISIBLE);
                    }
                }
            });
        }
    };
    t.scheduleAtFixedRate(task, 0, 1000);
}
}

这将完美地运作。我希望这会对你有所帮助。

Answer 3

很完美！ 100％

        package com.example.abc;

          import java.util.Random;
        import java.util.Timer;
       import java.util.TimerTask;

      import android.os.Bundle;
      import android.app.Activity;
     import android.content.Intent;
     import android.view.Menu;
  import android.view.View;
  import android.widget.Button;
   import android.widget.TextView;

      public class Test extends Activity {


      public Button B;
      public Button B1;
        public TextView S;
          int count=0;

       Random randomGenerator = new Random();
      int n;
       int i;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_test);


    B=new Button(this);
    B=(Button)findViewById(R.id.button1);
    B.setVisibility(View.INVISIBLE);

    B1=new Button(this);
    B1=(Button)findViewById(R.id.button2);
    B1.setVisibility(View.INVISIBLE);
    S=(TextView)findViewById(R.id.score);
        B.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            count+=1;
            S.setText(Integer.toString(count));
        }
    });
     B.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View arg0) {
    count+=1;
    S.setText(Integer.toString(count));
}
   });
    runThread();

}

private void runThread() {

    new Thread() {
        public void run() {
            while ( i++ < 1200) {
                if(i==1200){
                    startActivity(new Intent(Test.this,Game.class));
                    break;
                }
                try {
                    runOnUiThread(new Runnable() {

                        @Override
                        public void run() {
                            n = randomGenerator.nextInt(4)+1;

                            if(n==2){
                                B.setVisibility(View.VISIBLE);

                                B1.setVisibility(View.INVISIBLE);
                            }
                            if(n==4){
                                B.setVisibility(View.INVISIBLE);
                                B1.setVisibility(View.VISIBLE);
                            }
                        }
                    });
                    Thread.sleep(50);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }.start();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.test, menu);
    return true;
}
    }

应用程序App（进程com.example.app）意外停止

3 个答案: