6

我有一个嵌套在主要活动中的线程：

public class MainActivity extends Activity {

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

    new Thread(new Runnable(){
        public void run() {
            int myInt = 1;
            // Code below works fine and shows me myInt
            TextView textView = (TextView) findViewById(R.id.text_view);
            textView.setText(myInt);
        }
    }).start();

    // Code below doesn't work at all
    TextView textView = (TextView) findViewById(R.id.text_view);
    textView.setText(myInt);

}

我不确定这个结构是否正确。我应该如何将myInt变量传递给 Thread 以MainActivity使其在 Thread 之外变得可识别和可操作？

4

3 回答 3

1

在尝试设置线程外部（在主线程上）的文本视图之前，您首先需要一个已设置的整数的全局变量。它需要预先设置，因为您启动的新线程将简单地启动并移动到下一行代码，因此 myInt 尚未设置。

然后，至少在最初使用主线程上的 textview 的预定全局整数值。如果您想从您启动的线程中更改它，则在您的类中创建一个方法，如 setIntValue()，它将从线程中传递整数并将全局变量设置为该值。如果您愿意，我可以稍后更新代码示例。

更新：示例代码

public class MainActivity extends Activity {

//your global int
int myInt

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

new Thread(new Runnable(){
    public void run() {
        int myRunnableInt = 1;
        // Code below works fine and shows me myInt
        TextView textView = (TextView) findViewById(R.id.text_view);
        textView.setText(String.valueOf(myRunnableInt));

        //say you modified myRunnableInt and want the global int to reflect that...
        setMyInt(myRunnableInt);
    }
}).start();

//go ahead and initialize the global one here because you can't directly access your
myRunnableInt
myInt = 1;

TextView textView = (TextView) findViewById(R.id.text_view);
textView.setText(String.valueOf(myInt)); //now you will have a value here to use

//method to set the global int value
private void setMyInt(int value){
    myInt = value;

    //you could also reset the textview here with the new value if you'd like
    TextView textView = (TextView) findViewById(R.id.text_view);
    textView.setText(String.valueOf(myInt));
}
}

注意：如果您只希望能够重置 textview，而不是拥有一个全局的可操作变量，我建议将方法更改为只传入新整数并设置 textview，而不是存储全局变量，例如这：

private void setTextView(int newInt){
    TextView textView = (TextView) findViewById(R.id.text_view);
    textView.setText(String.valueOf(newInt));
}

如果您执行上述操作，请确保从线程内调用该方法时，在 UI 线程上调用它，如下所示： runOnUiThread(new Runnable()){ public void run(){ //update UI elements } }

于 2012-09-12T14:06:15.627 回答
0

改变

public class MainActivity extends Activity {
    // create activity field/member
    private int myIntValue;
    public void onCreate(Bundle savedInstanceState) {
    setContentView(R.layout.activity_main);

    runOnUiThread(new Runnable(){
        public void run() {
            myIntValue = 1;
            // Code below works fine and shows me myInt
            TextView textView = (TextView) findViewById(R.id.text_view);
            if (textView != null){
                textView.setText(myInt);
            }
        }
    });

    TextView textView = (TextView) findViewById(R.id.text_view);
    if (textView != null){
        textView.setText(myIntValue);
    }
}
于 2012-09-12T13:14:11.233 回答
-2

尝试以下操作：

public class MainActivity extends Activity 
{
    TextView textView;

    public void onCreate(Bundle savedInstanceState)
    {
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.text_view);
        new Thread(new Runnable()
        {
            public void run() 
            {
                int myInt = 1;
                textView.setText(myInt);
            }
        }).start();

    }
于 2012-09-12T13:14:38.340 回答