「Android/非同期処理/HandlerRunnable」の版間の差分

2020年8月17日 (月) 18:23時点における最新版

AsyncTaskはAndroid11から非推奨となったので非同期処理はこちら推奨。

サンプル

final TextView textView = findViewById(R.id.text1);
final Handler handler = new Handler(Looper.getMainLooper());
new Thread(new Runnable() {
    @Override
    public void run() {
        final String msg = "background exec";
        if (handler != null) {
            handler.post(new Runnable() {
                @Override
                public void run() {
                    if (textView != null) {
                        textView.setText(msg);
                    }
                }
            });
        }
    }
}).start();

参考：https://qiita.com/8yabusa/items/f8c9bb7eb81175c49e97

サンプル(Runnableクラス切り分け)

MainActivity.java

final TextView textView = findViewById(R.id.text1);
final Handler handler = new Handler(Looper.getMainLooper());
MyRunnableTask task = new MyRunnableTask(handler, textView);
new Thread(task).start();

MyRunnableTask.java

import android.os.Handler;
import android.widget.TextView;
public class MyRunnableTask implements Runnable {
    Handler mHandler;
    TextView mTextView;
    public MyRunnableTask(Handler handler, TextView textView) {
        mHandler = handler;
        mTextView = textView;
    }
    public void run() {
        final String msg = "background exec";
        if (mHandler != null) {
            mHandler.post(new Runnable() {
                @Override
                public void run() {
                    if (mTextView != null) {
                        mTextView.setText(msg);
                    }
                }
            });
        }
    }
}

参考：https://www.it-swarm.dev/ja/java/%E3%82%8F%E3%81%8B%E3%82%8A%E3%82%84%E3%81%99%E3%81%84%E8%AA%AC%E6%98%8E%E3%81%A7%E3%80%81java%E3%81%A7runnable%E3%81%A8%E3%81%AF%E4%BD%95%E3%81%A7%E3%81%99%E3%81%8B%EF%BC%9F/1070599643/

サンプル(ネットワーク処理&View処理)

ネットワーク処理はマルチスレッドで処理して、ViewはUiスレッドで処理する。 AsyncTaskの代替になる。

• doInBackground()の処理はhandler.post(new Runnable() {public void run(){}の中へ
• onPostExecute()の処理はuiHandler.post(new Runnable() {public void run(){}の中へ

MainActivity.java

final TextView textView = findViewById(R.id.text1);
final Handler uiHandler = new Handler(Looper.getMainLooper());

HandlerThread thread = new HandlerThread("other");
thread.start();
final Handler handler = new Handler(thread.getLooper());

MyRunnableTask task = new MyRunnableTask(uiHandler, handler, textView);
new Thread(task).start();

MyRunnableTask.java

import android.os.Handler;
import android.widget.TextView;
public class MyRunnableTask implements Runnable {
    Handler mUiHandler;
    Handler mHandler;
    TextView mTextView;
    public MyRunnableTask(Handler uiHandler, Handler handler, TextView textView) {
        mUiHandler = uiHandler;
        mHandler = handler;
        mTextView = textView;
    }
    public void run() {
        final String ret = "";
        if (mHandler != null) {
            mHandler.post(new Runnable() {
                @Override
                public void run() {
                    final CustomHttpURLConnection http = new CustomHttpURLConnection();
                    try {
                        String encode = URLEncoder.encode(param1, "UTF-8");
                        String url = "ttps://example.com/hoge?param1=" + encode;
                        http.execGet(url);
                        Log.i("http", http.getBody());
                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                    }
                    if (mUiHandler != null) {
                        mUiHandler.post(new Runnable() {
                            @Override
                            public void run() {
                                if (mTextView != null) {
                                    mTextView.setText(ret);
                                }
                            }
                        });
                   }
                }
            });
        }
    }
}

参考：https://www.it-swarm.dev/ja/java/%E3%82%8F%E3%81%8B%E3%82%8A%E3%82%84%E3%81%99%E3%81%84%E8%AA%AC%E6%98%8E%E3%81%A7%E3%80%81java%E3%81%A7runnable%E3%81%A8%E3%81%AF%E4%BD%95%E3%81%A7%E3%81%99%E3%81%8B%EF%BC%9F/1070599643/

callback処理

thread処理後に元処理を呼び出す。

MainActivity.java

final TextView textView = findViewById(R.id.text1);
final Handler uiHandler = new Handler(Looper.getMainLooper());
MyRunnableTask task = new MyRunnableTask(uiHandler, textView);
MyRunnableTask.CallbackInterface callback = new MyRunnableTask.CallbackInterface() {
    @Override
    public void callback() {
        Log.i("test", "callback");
    }
};
task.ThreadWithCallback(callback);
new Thread(task).start();

MyRunnableTask.java

public class MyRunnableTask implements Runnable {
    Handler mUiHandler;
    TextView mTextView;
    CallbackInterface mCallback;
    interface CallbackInterface {
        void callback();
    }
    public MyRunnableTask(Handler handler, TextView textView) {
        mUiHandler = handler;
        mTextView = textView;
    }
    void ThreadWithCallback(CallbackInterface callback) {
        mCallback = callback;
    }

    public void run() {
        final String msg = "update text string";
        if (mUiHandler != null) {
            mUiHandler.post(new Runnable() {
                @Override
                public void run() {
                    if (mTextView != null) {
                        mTextView.setText(msg);
                    }
                }
            });
        }
        mCallback.callback();
    }
}

参考：https://peitechblog.com/?p=260