finish() 不会在第一次关闭当前活动

Question

我正在尝试开发一个包含两个活动的应用程序，它们相互发送数据。 问题是我想finish();第二个活动。 当我单击我在 XML_ 中定义的goBackButton_ SecondActivity 出现时，当我再次单击该按钮时，它会如我所愿地返回到 MainActivity。 为什么？ 以及如何解决它？为什么它第一次不起作用？

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);
}



}

}

解决

Answer 1

问题出在你的代码上——

startActivity(intent);
startActivityForResult(intent, REQUEST_CODE);

当您想做startActivityForResult时，您不必做startActivity因为这将首先打开您的第二个活动而不寻找结果。

删除startActivity(intent);

Answer 2

您已经添加了startActivity(intent)以及创建活动的双重实例的startActivityforResult(intent, REQUEST_CODE)仅使用startActivityforResult(intent, REQUEST_CODE);

Answer 3

尝试删除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!");
}
});