android - 按两次返回退出

Question

Android 网页 View 我的应用程序中的当前代码是这样工作的:当用户按一次后退时，它会显示按钮询问“你想退出吗？”显示是或否选项。当我们选择是时，它会退出应用程序并显示插页式广告。如果您按“否”，它将保留在 Activity 中。

我想要的是:当用户按下后退时，它将转到上一个 Activity 。如果用户双击后退按钮然后它会要求退出，如果用户选择是。用户将退出应用程序并出现插页式广告。

请帮我解决这个问题。

主要 Activity :

public class MainActivity extends Activity{

private Fragment contentFragment;
String testDevice = "D0A04359EA1ECE9BA0CD4B6F457A9991";
String testDevice2 = "63C3530DA03C191310DB9AB8F0672E5C";
String testDevice3 = "801F2141A1DC3F743363AFDFDC42AF3A";
private InterstitialAd mInterstitialAd;
private AdView mAdView;
boolean displayAd = false;

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

    WebView mainWebView = (WebView) findViewById(R.id.mainWebView);
    WebSettings webSettings = mainWebView.getSettings();
    webSettings.setJavaScriptEnabled(true);
    mainWebView.setWebViewClient(new MyCustomWebViewClient());
    mainWebView.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
    mainWebView.loadUrl(this.getString(R.string.channel_url));

    mAdView = (AdView) findViewById(R.id.ad_view);
    // Create an ad request. Check your logcat output for the hashed device ID to
    // get test ads on a physical device. e.g.
    // "Use AdRequest.Builder.addTestDevice("ABCDEF012345") to get test ads on this device."
    AdRequest adRequest = new AdRequest.Builder()
            .addTestDevice(testDevice)
            .addTestDevice(testDevice2)
            .addTestDevice(testDevice3)
            .build();

    mAdView.setAdListener(new AdListener() {
        @Override
        public void onAdLoaded() {
            displayAd = true;
  //                View servername = findViewById(R.id.txt_List);
 //             RelativeLayout.LayoutParams layoutparams = 
(RelativeLayout.LayoutParams) servername.getLayoutParams();
//              layoutparams.addRule(RelativeLayout.BELOW, mAdView.getId());
//              layoutparams.removeRule(RelativeLayout.ALIGN_PARENT_TOP);
//              servername.setLayoutParams(layoutparams);
        }

        @Override
        public void onAdFailedToLoad(int errorCode) {
            if (!displayAd) {
            }
        }

        @Override
        public void onAdClosed() {
            // Proceed to the next level.
        }
    });

    // Start loading the ad in the background.
    mAdView.loadAd(adRequest);

getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);

    // Create the InterstitialAd and set the adUnitId (defined in values/strings.xml).
    mInterstitialAd = newInterstitialAd();
    loadInterstitial();
}

private class MyCustomWebViewClient extends WebViewClient {
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        view.loadUrl(url);
        return true;
    }
}

private InterstitialAd newInterstitialAd() {
    InterstitialAd interstitialAd = new InterstitialAd(this);
    interstitialAd.setAdUnitId(getString(R.string.interstitial_ad_unit_id));
    interstitialAd.setAdListener(new AdListener() {
        @Override
        public void onAdLoaded() {
        }

        @Override
        public void onAdFailedToLoad(int errorCode) {
        }

        @Override
        public void onAdClosed() {
            // Proceed to the next level.
            finish();
            //goToNextLevel();
        }
    });
    return interstitialAd;
}

private void showInterstitial() {
    // Show the ad if it's ready. Otherwise toast and reload the ad.
    if (mInterstitialAd != null && mInterstitialAd.isLoaded()) {
        mInterstitialAd.show();

    } else {
        finish();
    }
}

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
//      getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    return super.onOptionsItemSelected(item);
}

private void loadInterstitial() {
    // Disable the next level button and load the ad.
    AdRequest adRequest = new AdRequest.Builder()
            .addTestDevice(testDevice)
            .addTestDevice(testDevice2)
            .addTestDevice(testDevice3)
            .setRequestAgent("android_studio:ad_template").build();
    mInterstitialAd.loadAd(adRequest);
}


/*
 * We call super.onBackPressed(); when the stack entry count is > 0. if it
 * is instanceof EmpListFragment or if the stack entry count is == 0, then
 * we prompt the user whether to quit the app or not by displaying dialog.
 * In other words, from EmpListFragment on back press it quits the app.
 */

@Override
public void onBackPressed() {
    onShowQuitDialog();
}

public void onShowQuitDialog() {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setCancelable(false);

    builder.setMessage("Do You Want To Quit?");
    builder.setPositiveButton(android.R.string.yes,
            new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int id) {
                    showInterstitial();
                }
            });
    builder.setNegativeButton(android.R.string.no,
            new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    dialog.cancel();
                }
            });
    builder.create().show();
}

Answer 1

这是最简单的代码:

private static final int TIME_DELAY = 2000;
private static long back_pressed;

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

    @Override
    public void onBackPressed() {
        if (back_pressed + TIME_DELAY > System.currentTimeMillis()) {
            super.onBackPressed();
        } else {
            Toast.makeText(getBaseContext(), "Press once again to exit!",
                    Toast.LENGTH_SHORT).show();
        }
        back_pressed = System.currentTimeMillis();
    }
}