一键退出程序

public class ActivityCollector {
    public static List<Activity> activities = new ArrayList<>();
    public static void addActivity(Activity activity){
        activities.add(activity);
    }
    public static void removeActivity(Activity activity){
        activities.remove(activity);
    }
    public static void finishAll(){
        for (Activity activity : activities){
            if (!activity.isFinishing()){
                activity.finish();
            }
        }

    }

}

public class BaseActivity extends AppCompatActivity{
    private static final String TAG = "BaseActivity";

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, getClass().getName());
        ActivityCollector.addActivity(this);//将启动的活动都存入activities
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        ActivityCollector.removeActivity(this);//让退出的活动不再存储再activities
    }
}

//FirstActivity
public class FirstActivity extends BaseActivity {
    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        String tempData = "丢失的数据";
        outState.putString("maple",tempData);//第一个参数是键值，第二个参数是需要保存的数据
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode){
            case 1:
                if(resultCode == RESULT_OK){
                    String returnedData = data.getStringExtra("maple");
                    Toast.makeText(this,returnedData,Toast.LENGTH_SHORT).show();
                }
                break;
            default:
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.first_layout);
        if(savedInstanceState != null){
            String tempData = savedInstanceState.getString("maple");
            Toast.makeText(this,tempData,Toast.LENGTH_SHORT).show();
        }
        Button button1 = (Button)findViewById(R.id.button_1);
        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(FirstActivity.this,"You clicked Button 1",Toast.LENGTH_SHORT).show();
                Intent intent = new Intent(FirstActivity.this,SecondActivity.class);
                startActivityForResult(intent,1);

            }
        });
        button1.setText("走你");


    }

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

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()){
            case R.id.add_item:
                Toast.makeText(this,"You clicked Add",Toast.LENGTH_SHORT).show();
                break;
            case R.id.remove_item:
                Toast.makeText(this,"You clicked Remove",Toast.LENGTH_SHORT).show();
                break;
        }
        return true;
    }
}

//SecondActivity
public class SecondActivity extends BaseActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        Button button2 = (Button)findViewById(R.id.button_2);
        Intent intent = new Intent();//只用来携带被传递的值，不跳转活动
        String data = "Hello FirstActivity";
        intent.putExtra("maple",data);
        setResult(RESULT_OK,intent);
        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
               ActivityCollector.finishAll();//销毁所有活动
            }
        });
    }
}