java-在Android中制作一個chronometer計時器

在Android中制作一個chronometer計時器

我想在Android中制作一個chronometer計時器，使用了timer和sheduleAtFixedRate 方法。看起來像是在timer的run方法中調用textview後，程序就會出錯停止運行。我用的是以下的代碼，哪裡出錯了呢？

Button boton_iniciar;
TextView texto_cronometro;
Timer count;
int a = 0;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_cronometro);

    /**********************/
    boton_iniciar = (Button) findViewById(R.id.button1);
    texto_cronometro = (TextView) findViewById(R.id.textView1);
    count= new Timer("Contador");
    boton_iniciar.setOnClickListener(new OnClickListener() {

        public void onClick(View v) {
            // TODO Auto-generated method stub
            count.scheduleAtFixedRate(new TimerTask() {         
                @Override
                public void run() {
                    // TODO Auto-generated method stub
                    a++;
                    texto_cronometro.setText(String.valueOf(a));
                }
            }, 100, 100);
        }
    });
}

最佳回答：

所有要改變UI對象的的action都應該在主UI中運行。

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_cronometro);

    /**********************/
    boton_iniciar = (Button) findViewById(R.id.button1);
    texto_cronometro = (TextView) findViewById(R.id.textView1);
    count= new Timer("Contador");
    boton_iniciar.setOnClickListener(new OnClickListener() {

        public void onClick(View v) {
            // TODO Auto-generated method stub
            count.scheduleAtFixedRate(new TimerTask() {         
                @Override
                public void run() {
                    // TODO Auto-generated method stub
                    a++;
                    ActivityCronometro.this.runOnUiThread(new Runnable() {          
                    @Override
                    public void run() {
                        texto_cronometro.setText(String.valueOf(a));

                    }
                });

                }
            }, 100, 100);
        }
    });
}