Java 如何使用getIntent（）更新主活动？

当nav_gallery=true时，它会将我带到activity2，其中包含以下代码：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //identify object

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

    **title = (TextView)findViewById(R.id.theTitle);
    Intent intent = getIntent();
    String Title = intent.getExtras().getString("name");
    title.setText(Title);**
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_camera) {
        // Handle the camera action

    } else if (id == R.id.nav_gallery) {
        Intent intent = new Intent(this, addCounter.class);
        startActivity(intent);

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

我想将activity2中的信息发送回主activity。我的getIntent（）是否位于错误的位置？

您的getIntent（）方法位于onCreate方法中。 但是onCreate在创建时只调用一次。如果MainActivity仍在堆栈中，则没有理由再次调用onCreate（）

您应该尝试在onResume（）或onStart（）中插入代码

    public void addOk(){
    String sendName = name.getText().toString();
    Intent intent = new Intent(this, MainActivity.class);
    intent.putExtra("name", sendName);
    startActivity(intent);
}