kingori/WebViewActivity.java

## WebViewActivity.java
public class WebViewActivity extends Activity {

    WebView wv;
    LinkedList<JsResult> jsResults = new LinkedList<>();

    @TargetApi(Build.VERSION_CODES.KITKAT)
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_wv);

        WebView.setWebContentsDebuggingEnabled(true);
        wv = findViewById(R.id.wv);
        wv.getSettings().setJavaScriptEnabled(true);
        WebChromeClient wc = new WebChromeClient(){
            @Override
            public boolean onJsAlert(WebView view, String url, String message, final JsResult result) {
                jsResults.add(result);
                new AlertDialog.Builder(WebViewActivity.this).setMessage(message)
                        .setOnCancelListener(new DialogInterface.OnCancelListener() {
                            @Override
                            public void onCancel(DialogInterface dialogInterface) {
                                jsResults.remove(result);
                                result.cancel();
                            }
                        }).show();
                return  true;
            }

            @Override
            public boolean onJsConfirm(WebView view, String url, String message, final JsResult result) {
                jsResults.add(result);
                new AlertDialog.Builder(WebViewActivity.this).setMessage(message)
                        .setOnCancelListener(new DialogInterface.OnCancelListener() {
                            @Override
                            public void onCancel(DialogInterface dialogInterface) {
                                jsResults.remove(result);
                                result.cancel();
                            }
                        })
                        .setNegativeButton("cancel", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialogInterface, int i) {
                                dialogInterface.cancel();
                            }
                        })
                        .setPositiveButton("confirm", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialogInterface, int i) {
                                jsResults.remove(result);
                                result.confirm();
                            }
                        })
                        .show();
                return  true;
            }
        };
        wv.setWebChromeClient(wc);
        wv.loadData("<html><head><script>function myAlert() { \n\r alert('haha'); \n\r}\n\r\n\r" +
                " window.setTimeout(myAlert, 500);</script></head><body>aaa</body></html>","text/html", "utf-8");
    }

    @Override
    protected void onDestroy() {
        Toast.makeText(this, "onDestroy", Toast.LENGTH_SHORT).show();
        wv.destroy();

        for(JsResult jsResult: jsResults ) {
            jsResult.cancel();
        }

        super.onDestroy();
    }
}
	public class WebViewActivity extends Activity {

	WebView wv;
	LinkedList<JsResult> jsResults = new LinkedList<>();

	@TargetApi(Build.VERSION_CODES.KITKAT)
	@Override
	protected void onCreate(@Nullable Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_wv);

	WebView.setWebContentsDebuggingEnabled(true);
	wv = findViewById(R.id.wv);
	wv.getSettings().setJavaScriptEnabled(true);
	WebChromeClient wc = new WebChromeClient(){
	@Override
	public boolean onJsAlert(WebView view, String url, String message, final JsResult result) {
	jsResults.add(result);
	new AlertDialog.Builder(WebViewActivity.this).setMessage(message)
	.setOnCancelListener(new DialogInterface.OnCancelListener() {
	@Override
	public void onCancel(DialogInterface dialogInterface) {
	jsResults.remove(result);
	result.cancel();
	}
	}).show();
	return true;
	}

	@Override
	public boolean onJsConfirm(WebView view, String url, String message, final JsResult result) {
	jsResults.add(result);
	new AlertDialog.Builder(WebViewActivity.this).setMessage(message)
	.setOnCancelListener(new DialogInterface.OnCancelListener() {
	@Override
	public void onCancel(DialogInterface dialogInterface) {
	jsResults.remove(result);
	result.cancel();
	}
	})
	.setNegativeButton("cancel", new DialogInterface.OnClickListener() {
	@Override
	public void onClick(DialogInterface dialogInterface, int i) {
	dialogInterface.cancel();
	}
	})
	.setPositiveButton("confirm", new DialogInterface.OnClickListener() {
	@Override
	public void onClick(DialogInterface dialogInterface, int i) {
	jsResults.remove(result);
	result.confirm();
	}
	})
	.show();
	return true;
	}
	};
	wv.setWebChromeClient(wc);
	wv.loadData("<html><head><script>function myAlert() { \n\r alert('haha'); \n\r}\n\r\n\r" +
	" window.setTimeout(myAlert, 500);</script></head><body>aaa</body></html>","text/html", "utf-8");
	}

	@Override
	protected void onDestroy() {
	Toast.makeText(this, "onDestroy", Toast.LENGTH_SHORT).show();
	wv.destroy();

	for(JsResult jsResult: jsResults ) {
	jsResult.cancel();
	}

	super.onDestroy();
	}
	}