java - 访问内部类变量到另一个方法

Question

请帮忙。我不是一个普通的java作家，所以我无法解决这个问题:onCreate 方法中的 getLastLocation() 对于 Lat 和 Lang 返回 0.0，而该值在 code>getLastLocation() 方法本身。另外，AndroidStudio 表示，在 getLastLocation 中，从未使用过 Lat 和 Lang 参数。

请帮我解决这个难题。

 @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Bundle bundle = new Bundle();
    bundle.putDouble  ("loclat", 25.4358);
    bundle.putDouble("loclang", 81.8463);
    Fragment SunFragment = new SunFragment();
    SunFragment.setArguments(bundle);
    setContentView(R.layout.activity_main);

    mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);

    getLastLocation(Lat, Long);
    //Value is 0 here
    Toast.makeText(getApplicationContext(),Double.toString(Lat), Toast.LENGTH_LONG).show();  
      SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this,
          getSupportFragmentManager(), Lat, Long);
      ViewPager viewPager = findViewById(R.id.view_pager);
      viewPager.setAdapter(sectionsPagerAdapter);
      TabLayout tabs = findViewById(R.id.tabs);
      tabs.setupWithViewPager(viewPager);

  }
  @SuppressLint("MissingPermission")
  public void getLastLocation(double Lat, double Long){
    if (checkPermissions()) {
      if (isLocationEnabled()) {
        mFusedLocationClient.getLastLocation().addOnCompleteListener(
            new OnCompleteListener<Location>() {
              @Override
              public void onComplete(@NonNull Task<Location> task) {
                Location location = task.getResult();
                if (location == null) {
                  requestNewLocationData();
                } else {
                 final double Lat = location.getLatitude();
                 final double Long = location.getLongitude();
                 // Giving the value here
                 Toast.makeText(getApplicationContext(),"Long"+ Long, Toast.LENGTH_LONG).show();   
                }
              }
            }
        );
      } else {
        Toast.makeText(this, "Turn on location", Toast.LENGTH_LONG).show();
        Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
        startActivity(intent);
      }
    } else {
      requestPermissions();
    }
  }

Answer 1

获取Lat和Long数据后尝试使用Tab设置ViewPager

private Double Lat;
private Double Long;

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

    mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
    getLastLocation();
}

private void setupViewPager() {
    Toast.makeText(getApplicationContext(),Double.toString(Lat), Toast.LENGTH_LONG).show();
    SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this,
            getSupportFragmentManager(), Lat, Long);
    ViewPager viewPager = findViewById(R.id.view_pager);
    viewPager.setAdapter(sectionsPagerAdapter);
    TabLayout tabs = findViewById(R.id.tabs);
    tabs.setupWithViewPager(viewPager);
}

@SuppressLint("MissingPermission")
public void getLastLocation(){
    if (checkPermissions()) {
        if (isLocationEnabled()) {
            mFusedLocationClient.getLastLocation().addOnCompleteListener(
                    new OnCompleteListener<Location>() {
                        @Override
                        public void onComplete(@NonNull Task<Location> task) {
                            Location location = task.getResult();
                            if (location == null) {
                                requestNewLocationData();
                            } else {
                                Lat = location.getLatitude();
                                Long = location.getLongitude();
                                // Giving the value here
                                Toast.makeText(getApplicationContext(),"Long"+ Long, Toast.LENGTH_LONG).show();

                                setupViewPager();
                            }
                        }
                    }
            );
        } else {
            Toast.makeText(this, "Turn on location", Toast.LENGTH_LONG).show();
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            startActivity(intent);
        }
    } else {
        requestPermissions();
    }
}

建议:您可以使用回调在 Activity 和 Fragment 之间进行通信，而不是将数据传递给 Fragment。检查this了解如何在Activity和Fragment之间进行通信