android Activity finish方法

android Activity finish方法放在不同的地方會有不同的效果：

 

1、放在MainActivity測oncreate方法內：

public class MainActivity extends AppCompatActivity {

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

        //ßrequestWindowFeature(Window.FEATURE_NO_TITLE);

        Log.d("MainActivity", "onCreate+++++++++++++++++++++++");


        Intent intent = getIntent();



        Button btn = findViewById(R.id.button2);
        btn.setOnClickListener(new View.OnClickListener()
        {
            public  void onClick(View v)
            {
                Log.d("MainActivity", "onClick+++++++++++++++++++++++");
                //EditText text = findViewById(R.id.editText);
                //text.setText("Fucking Android");

                Toast.makeText(MainActivity.this, "Button is Clicked", Toast.LENGTH_LONG).show();



                Uri uri = Uri.parse("smsto:0800000123");
                Intent it = new Intent(Intent.ACTION_SENDTO, uri);

                it.setData(uri);
                it.putExtra("sms_body", "The SMS text");
                startActivity(it);
                finish();


            }
        });

        //直接放在activity oncteate裏，會導致程序直接閃退結束
        finish();

    }
}

2、放在intent後的startActivity()後：

public class MainActivity extends AppCompatActivity {

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

        //ßrequestWindowFeature(Window.FEATURE_NO_TITLE);

        Log.d("MainActivity", "onCreate+++++++++++++++++++++++");


        Intent intent = getIntent();



        Button btn = findViewById(R.id.button2);
        btn.setOnClickListener(new View.OnClickListener()
        {
            public  void onClick(View v)
            {
                Log.d("MainActivity", "onClick+++++++++++++++++++++++");
                //EditText text = findViewById(R.id.editText);
                //text.setText("Fucking Android");

                Toast.makeText(MainActivity.this, "Button is Clicked", Toast.LENGTH_LONG).show();



                Uri uri = Uri.parse("smsto:0800000123");
                Intent it = new Intent(Intent.ACTION_SENDTO, uri);

                it.setData(uri);
                it.putExtra("sms_body", "The SMS text");
                startActivity(it);
                finish();


            }
        });

        //直接放在activity oncteate裏，會導致程序直接閃退結束
        //finish();

    }
}

則是啓動目標程序後，當前程序結束