Question

我正在开发运行Android 7.1.1的Google Pixel。

以下是2项活动，PlayActivity和ScoreScreenActivity。流程应该看起来像Main＆gt;播放＆gt;游戏＆gt;得分＆gt; [后退按钮]＆gt;播放＆gt; [后退按钮]＆gt;主要。

在ScoreScreenActivity中按下后退按钮时，将调用onKeyPressed（）方法。我们被重定向到PlayActivity。到现在为止还挺好。现在我们处于PlayActivity状态，当再次按下后退按钮时，我们会不正确地从名为ScoreScreenActivity的Activity重定向回GameActivity。我们应该将其发送给MainActivity。

另外，我在GameActivity和ScoreScreenActivity中的startActivity（）后面有finish（）。此外，当我们从ScoreScreenActivity转到PlayActivity时会显示此错误：

W/ViewRootImpl[ScoreScreenActivity]: Cancelling event due to no window focus: KeyEvent

以下是活动代码：不起作用的代码：

public class PlayActivity extends AppCompatActivity {

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

    Button mOneMinute = (Button) findViewById(R.id.play_one_minute);
    if (mOneMinute!=null){
        mOneMinute.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(PlayActivity.this, GameActivity.class);
                startActivity(intent);
                finish();
            }
        });

    }
}
@Override
public void onBackPressed(){
    System.out.println("this isn't printed either");
    // AlertDialog happens here
}
// Copy & Pasted from another StackOverFlow (http://stackoverflow.com/questions/16646301/onbackpressed-is-not-being-called)
@Override
public boolean onKeyDown(int keyCode, KeyEvent event)  {
    System.out.println("never gets printed");
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        Log.d("back", "should go back to MainActivity");
        Intent i=new Intent(PlayActivity.this, MainActivity.class);
        startActivity(i);
        finish();
    }
    return true;
}

功能代码：

    public class ScoreScreenActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_score_screen);
        int score = 0;
        Intent intent = getIntent();
        score = intent.getIntExtra("mScore", score);
        System.out.println(score);

        TextView mTV = (TextView) findViewById(R.id.score_text);
        if (mTV != null ){
            mTV.setTextSize(20);
            mTV.setTextAlignment(View.TEXT_ALIGNMENT_CENTER);
            String str = "Well Done!\nYour Score: "+ score +"\nThere's no high score system for now,\n" +
                    "so remember this score\nif it's a new high score!";
            SpannableString ss = new SpannableString(str);
            ss.setSpan(new RelativeSizeSpan(2), 0, 25, 0);
            mTV.setText(ss);
        }
        Button mReturn = (Button) findViewById(R.id.score_return);
        if (mReturn!= null){
            mReturn.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Intent returnIntent = new Intent(ScoreScreenActivity.this, MainActivity.class);
                    startActivity(returnIntent);
                }
            });
        }

    }

    @Override
    public void onBackPressed(){
        System.out.println("this does not get printed");
        // AlertDialog happens here
    }

    // Copy & Pasted from another StackOverFlow (http://stackoverflow.com/questions/16646301/onbackpressed-is-not-being-called)
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event)  {
        System.out.println("this gets printed");
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            Log.e("back",""+1);
            Intent i=new Intent(ScoreScreenActivity.this,PlayActivity.class);
            startActivity(i);
            finish();
        }
        return true;
    }
}

Answer 1

您可以这样处理：

适用于API级别5及更高版本的

（新）

@Override
public void onBackPressed() {
    // your code.
}

早于API 5

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        // your code
        return true;
    }

    return super.onKeyDown(keyCode, event); // u are missing this 
}

没有调用Android 7.1.1后退按钮的方法

1 个答案: