finish（）不會在第一時間關閉當前活動

Question

我正在嘗試開發一個具有兩個活動的應用程序，它們可以相互發送數據。 問題是我想finish(); 第二項活動。 當我單擊我在XML_中定義的goBackButton_時，出現第二個活動，當我再次單擊該按鈕時，它會根據需要返回到MainActivity。 為什么？ 以及如何解決？為什么第一次不起作用？

public class MainActivity extends AppCompatActivity {
Button button;
int REQUEST_CODE = 1;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    button = (Button) findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(MainActivity.this,SecondActivity.class);
            intent.putExtra("FirstActivity", "Hello from first activity");
            startActivity(intent);

            startActivityForResult(intent, REQUEST_CODE);
            Log.d("TAG", "onClickListener: done!");
        }
    });
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    //super.onActivityResult(requestCode, resultCode, data);
    Log.d("TAG", "onActivityResult: Entered");
    if(requestCode == REQUEST_CODE) {
        Log.d("TAG", "onActivityResult: requestCode is OK");
        if (resultCode == RESULT_OK) {
            Log.d("TAG", "onActivityResult: result is returned OK");
            String result = data.getStringExtra("SecondActivity");
            Toast.makeText(this, result, Toast.LENGTH_LONG).show();
            Log.d("TAG", "onActivityResult: done!");
        }
    }






}

}

public class SecondActivity extends AppCompatActivity {
TextView textView;
Button goBackButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);
    goBackButton = (Button) findViewById(R.id.goBackButton);
    goBackButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Log.d("TAG", "onClick: Entered");
            Intent returnIntent = getIntent();
            returnIntent.putExtra("SecondActivity", "from second Activity");
            setResult(RESULT_OK, returnIntent);
            Log.d("TAG", "onClick: Message sent");
            finish();
            Log.d("TAG", "onClick: Activity finished");
            //Intent myIntent = new Intent(SecondActivity.this,MainActivity.class);
            //startActivity(myIntent);

        }
    });
    textView = (TextView)findViewById(R.id.textView);
    Bundle extras = getIntent().getExtras();
    if(extras != null){
        String string = extras.getString("FirstActivity");
        textView.setText(string);
    }






}

}

解決了

Answer 1

問題出在您的代碼中-

startActivity(intent);

startActivityForResult(intent, REQUEST_CODE);

當您想要執行startActivityForResult您不必執行startActivity因為這將首先打開您的第二個活動而不尋找結果。

刪除startActivity(intent);

Answer 2

您已經添加了startActivity(intent)以及startActivityforResult(intent, REQUEST_CODE) ，它們僅使用startActivityforResult(intent, REQUEST_CODE)創建活動的雙重實例；

Answer 3

嘗試刪除startActivity（intent）;

button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Intent intent = new Intent(MainActivity.this,SecondActivity.class);
        intent.putExtra("FirstActivity", "Hello from first activity");
        startActivityForResult(intent, REQUEST_CODE);
        Log.d("TAG", "onClickListener: done!");
    }
});