onBack pressed（）对我不起作用 [英] onBackPressed() doesn't work for me
本文介绍了onBack pressed（）对我不起作用的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个问题，这也是在这里讨论： onBack pressed不会被调用
我想取消时$ P $从Android手机pssing本机背按钮CountDownTimer。所以我想overrite的onBack pressed方法，来取消计时器并返回到另一个活动，但只有一次。 （返回的主要活动，就像一个home键）。
这是的code部分：
保护无效的onCreate（包savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.activity_my）;
如果（getResources（）。getConfiguration（）。方向== Configuration.ORIENTATION_LANDSCAPE）{
ImageView的und1 =（ImageView的）findViewById（R.id.undita1）;
ViewGroup.LayoutParams PARAMS =（ViewGroup.LayoutParams）und1.getLayoutParams（）;
params.height = 150;
und1.setLayoutParams（PARAMS）;
ImageView的und2 =（ImageView的）findViewById（R.id.undita2）;
ViewGroup.LayoutParams params2 =（ViewGroup.LayoutParams）und2.getLayoutParams（）;
params2.height = 150;
und2.setLayoutParams（params2）;
ImageView的und3 =（ImageView的）findViewById（R.id.undita3）;
ViewGroup.LayoutParams params3 =（ViewGroup.LayoutParams）und3.getLayoutParams（）;
params3.height = 150;
und3.setLayoutParams（params3）;
}
mProgressBar =（进度）findViewById（R.id.progressBar）;
mProgressBar.setProgress（0）;
mCountDownTimer =新CountDownTimer（90000,1000）{
INT I = 0;
@覆盖
公共无效onTick（长millisUntilFinished）{
Log.v（Log_tag，蜱进展+ 1 + millisUntilFinished）;
我++;
mProgressBar.setProgress（ⅰ）; }
@覆盖
公共无效onFinish（）{
我++;
mProgressBar.setProgress（ⅰ）;
意图=新的意图（getApplicationContext（），MyActivity2.class）;
startActivity（在）;
}
};
mCountDownTimer.start（）;
android.view.Display显示=（（android.view.WindowManager）getSystemService（Context.WINDOW_SERVICE））getDefaultDisplay（）。
叠B;
B = getIntent（）getExtras（）。
NIVEL = b.getInt（水平）;
TextView中证=（TextView中）findViewById（R.id.Nivel）;
niv.setText（级别：+ NIVEL）;
generare_3_diferente（NIVEL）;}
@覆盖
公共布尔onCreateOptionsMenu（功能菜单）{
。getMenuInflater（）膨胀（R.menu.my，菜单）;
返回true;}
@覆盖
公共布尔onOptionsItemSelected（菜单项项）{
INT的id = item.getItemId（）;
如果（ID == R.id.action_settings）{
返回true;
}
返回super.onOptionsItemSelected（项目）;
}
@覆盖
公共布尔的onkeydown（INT键code，KeyEvent的事件）{
如果（（钥匙code == KeyEvent.KEY code_BACK））{//返回键pressed
mCountDownTimer.cancel（）;
意图=新的意图（getApplicationContext（），MyActivity2.class）;
startActivity（在）;
mCountDownTimer.cancel（）;
返回true;
}其他{
返回super.onKeyDown（键code，事件）;
}
}
@覆盖
公共无效onBack pressed（）{
mCountDownTimer.cancel（）;
意图=新的意图（这一点，MyActivity2.class）;
startActivity（在）;
super.onBack pressed（）;
}
}
解决方案
在onBack pressed应该是在主要活动类
也可以尝试以指定的应用程序，例如的清单文件
父子活动 安卓parentActivityName
和尝试使用这样的事情并重建你的应用程序
@覆盖
公共无效onBack pressed（）{
super.onBack pressed（）;
I =新的意图（CurrentActivity.this，NextActivity.class）;
i.setFlags（Intent.FLAG_ACTIVITY_CLEAR_TOP）;
startActivity（ⅰ）;
完（）;
}
如果仍然无法正常工作，尽量使新的应用和导入文件
I have a problem, which is also discussed here: onBackPressed never gets called
I'm trying to cancel a CountDownTimer when pressing the native back button from an android phone. So I would like to overrite the onBackPressed method, to cancel the timer and return to another activity, but only once. (to return to the main activity, like a home button).
This is a part of the code:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
if (getResources().getConfiguration().orientation== Configuration.ORIENTATION_LANDSCAPE){
ImageView und1=(ImageView)findViewById(R.id.undita1);
ViewGroup.LayoutParams params = (ViewGroup.LayoutParams) und1.getLayoutParams();
params.height=150;
und1.setLayoutParams(params);
ImageView und2=(ImageView)findViewById(R.id.undita2);
ViewGroup.LayoutParams params2 = (ViewGroup.LayoutParams) und2.getLayoutParams();
params2.height=150;
und2.setLayoutParams(params2);
ImageView und3=(ImageView)findViewById(R.id.undita3);
ViewGroup.LayoutParams params3 = (ViewGroup.LayoutParams) und3.getLayoutParams();
params3.height=150;
und3.setLayoutParams(params3);
}
mProgressBar=(ProgressBar)findViewById(R.id.progressBar);
mProgressBar.setProgress(0);
mCountDownTimer=new CountDownTimer(90000,1000) {
int i=0;
@Override
public void onTick(long millisUntilFinished) {
Log.v("Log_tag", "Tick of Progress" + i + millisUntilFinished);
i++;
mProgressBar.setProgress(i); }
@Override
public void onFinish() {
i++;
mProgressBar.setProgress(i);
Intent in = new Intent(getApplicationContext(), MyActivity2.class);
startActivity(in);
}
};
mCountDownTimer.start();
android.view.Display display = ((android.view.WindowManager)getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
Bundle b;
b = getIntent().getExtras();
nivel= b.getInt("level");
TextView niv=(TextView) findViewById(R.id.Nivel);
niv.setText("Level: "+ nivel);
generare_3_diferente(nivel);}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.my, menu);
return true;}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) { //Back key pressed
mCountDownTimer.cancel();
Intent in = new Intent(getApplicationContext(), MyActivity2.class);
startActivity(in);
mCountDownTimer.cancel();
return true;
}else{
return super.onKeyDown(keyCode, event);
}
}
@Override
public void onBackPressed(){
mCountDownTimer.cancel();
Intent in = new Intent(this, MyActivity2.class);
startActivity(in);
super.onBackPressed();
}
}
解决方案
the onBackPressed should be in the main activity class
Also try to specify the parent and child activities in the manifest file of the app e.g
android:parentActivityName
and try to use something like this and rebuild your App
@Override
public void onBackPressed() {
super.onBackPressed();
i = new Intent(CurrentActivity.this, NextActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
finish();
}
if it still doesn't work try to make a new application and import your files
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