java - 当我使用异步时，按钮 onClick 收到 2 条错误消息

Question

我的代码有什么问题吗？它显示错误:

<强>1。无法解析方法 onCreate 'onCreate.android.os.Bundle'
2.方法不会在@Override上覆盖其父类(super class)的方法

这是收到错误消息的部分

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

            BUTTON = (Button) findViewById(R.id.button);

            BUTTON.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    DemoAsync UploadFile = new DemoAsync();
                    UploadFile.execute();
                }
            });

        }

这是 MainActivity.java 上的全部代码

 package com.example.threadexample;

        import androidx.appcompat.app.AppCompatActivity;
        import android.util.Log;
        import android.os.AsyncTask;
        import android.os.Bundle;
        import android.view.View;
        import android.widget.Button;
        import android.widget.TextView;


        public class MainActivity extends AppCompatActivity {

            public static final String DEMO_ASYNC = "DemoAsync";
            private TextView B_PRESSED;
            Button BUTTON;

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);
                B_PRESSED = (TextView) findViewById(R.id.myTextView);
                DemoAsync demoAsync = new DemoAsync();
                demoAsync.execute("Button Pressed");

            }

            private class DemoAsync extends AsyncTask<String, Void, String> {
                @Override
                protected void onPreExecute() {
                    super.onPreExecute();
                }

                protected String doInBackground(String... params) {

                    Log.d(DEMO_ASYNC, "status : doInBackground");
                    try {
                        Thread.sleep(20000);
                    } catch (Exception e) {
                        Log.d(DEMO_ASYNC, e.getMessage());
                    }
                    return params[0];
                }

                @Override
                protected void onPostExecute(String s) {
                    super.onPostExecute(s);
                    B_PRESSED.setText(s);
                }

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

                    BUTTON = (Button) findViewById(R.id.button);

                    BUTTON.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {
                            DemoAsync UploadFile = new DemoAsync();
                            UploadFile.execute();
                        }
                    });

                }
            }
        }

请详细说明我应该更改哪些部分，我是新来的。感谢您的理解。

Answer 1

试试这个，希望能成功

package com.example.threadexample;

import androidx.appcompat.app.AppCompatActivity;
import android.util.Log;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.marsad.wallpaperapp.R;


public class MainActivity extends AppCompatActivity {

    public static final String DEMO_ASYNC = "DemoAsync";
    private TextView B_PRESSED;
    Button BUTTON;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        B_PRESSED = (TextView) findViewById(R.id.myTextView);
        DemoAsync demoAsync = new DemoAsync();
        demoAsync.execute("Button Pressed");

        BUTTON = (Button) findViewById(R.id.button);

        BUTTON.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                DemoAsync UploadFile = new DemoAsync();
                UploadFile.execute();
            }
        });

    }

    private class DemoAsync extends AsyncTask<String, Void, String> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        protected String doInBackground(String... params) {

            Log.d(DEMO_ASYNC, "status : doInBackground");
            try {
                Thread.sleep(20000);
            } catch (Exception e) {
                Log.d(DEMO_ASYNC, e.getMessage());
            }
            return params[0];
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            B_PRESSED.setText(s);
        }
    }
}