Question

此代码在MainActivity的OnCreate中

    inflater = getLayoutInflater();
    serversView = inflater.inflate(R.layout.layout_home, null, false);
    test = serversView.findViewById(R.id.titleDescription);

    Thread thread = new Thread(new Runnable() {
        @Override
        public void run() {
            try  {


                    //some code
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {

                            test.setText(utf8text+"mk");

                            Log.i(LOG_TAG,"serversView: "+ serversView + " test: "+ test + " test.getText().toString():"+ test.getText().toString());
                        }
                    });


            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });

    thread.start();

必须使用Thread类！当我登录Log.i(LOG_TAG," test.getText().toString():"+ test.getText().toString());时，一切正常，文本已更改，但在UI中什么也没做。怎么了？

UPD：当我这样做时：

runOnUiThread(new Runnable() { @Override public void run() { textView.setText(utf8text); Log.i(LOG_TAG,"textView.getText: "+ textView.getText().toString()); } });

，如果textView在main_activity.xml中，则它会更改。但是，例如，如何使用LayoutInflater获取和更改另一个片段/活动中的TextView？

Answer 1

在运行方法中添加以下行

serversView.invalidateViews（）;

例如

public void run() {
    test.setText(utf8text+"mk");
    serversView.invalidateViews();
    Log.i(LOG_TAG,"serversView: "+ serversView + " test: "+ test + "test.getText().toString():"+ test.getText().toString());
}

Answer 2

非UI线程无法更新UI，但是android提供了android.os.Handler类或AsyncTasks类，以下是线程处理程序尝试的示例代码。

public class MainActivity extends AppCompatActivity {
private ProgressBar progress;
private TextView text;
Handler handler;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    progress = findViewById(R.id.progressBar1);
    text = findViewById(R.id.textView1);
    handler = new Handler();
}
public void startProgress(View view) {
    // do something long
    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            for (int i = 0; i <= 10; i++) {
                final int value = i;
                doFakeWork();
                handler.post(new Runnable(){
                    @Override
                    public void run() {
                        progress.setProgress(value);
                        if(value!=10)
                            text.setText("updated");
                        else
                            text.setText("updating");
                    }
                });
            }
        }
    };
    new Thread(runnable).start(); }
    // Simulating something timeconsuming
private void doFakeWork() {
    try { SystemClock.sleep(5000);} catch (Exception e) {e.printStackTrace();}}}

希望它对您有帮助，祝您好运。

Answer 3

线程处理程序类，尝试一下。

public class MainActivity extends AppCompatActivity {

TextView test;
Handler handle;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    test = findViewById(R.id.titleDescription);
    handle = new Handler();

    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            test.setText("Hey! Text Changed");
        }
    };
    new Thread(runnable).start();

}

}

当我更改文本并将其显示在Thread中的UI上时，什么也没做（JAVA）

3 个答案: