android - TextView 没有及时更新

Question

我有以下示例代码来理解 TextView 更新

public class MainActivity extends Activity 
{
    int i=0;    
    private ImageButton btnMain;
    private TextView txtText;
    Context mycont=null;

    public void myJob(final String cmd)
    { 
        //txtText.setText(cmd);

        runOnUiThread(new Runnable() 
        {
            @Override
            public void run() {
                txtText.setText(cmd); //---Does not update the TextView here on Main UI
            }
        });     

        //----------- Long Work(Take around 15 seconds to complete) ----------
        for(i=0;i<=1000000000;i++)
        i++;                        

        for(i=0;i<=1000000000;i++)
        i++;
        //--------------------------------------------------------------------

        //---Update the TextView here once above Long work is executed
    }


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

        mycont=this;

        txtText = (TextView) findViewById(R.id.txtText);
        txtText.setMovementMethod(new ScrollingMovementMethod());


        btnMain = (ImageButton) findViewById(R.id.btnJob);          
        btnMain.setOnClickListener(new View.OnClickListener() 
        {
            @Override
            public void onClick(View v) 
            {   
                myJob("Display this msg");
            }
        });
    }
}

TextView 没有按时更新，正在等待其他过程执行。请指出我正确的方向。我想在 myJob() 函数的开头更新 TextView。

Answer 1

查看此链接:How will UI changes be processed in the onClickListener before starting a new activity in Android?

“对 UI 元素的更改不会立即执行。它们会在下次 UI 循环运行时执行，也就是在您释放控制权之后。”