Not an enclosing class error Android Studio

问题:

I am new in android development and do not have an in depth knowledge of Java. I am stuck on a problem for a long time. I am trying to open a new activity on button click. But I am getting an error that error: not an enclosing class: Katra_home.

Here is the code for MainActivity.java

public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Button btn=(Button)findViewById(R.id.bhawan1);
   btn.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Intent myIntent = new Intent(Katra_home.this, Katra_home.class);
            Katra_home.this.startActivity(myIntent);
        }
    });

And this is the code for Katra_home.java

public class Katra_home extends BaseActivity {

protected static final float MAX_TEXT_SCALE_DELTA = 0.3f;

private ViewPager mPager;
private NavigationAdapter mPagerAdapter;
private SlidingTabLayout mSlidingTabLayout;
private int mFlexibleSpaceHeight;
private int mTabHeight;


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

    ActionBar ab = getSupportActionBar();
    if (ab != null) {
        ab.setDisplayHomeAsUpEnabled(true);
        ab.setHomeButtonEnabled(true);
    }

Though I have seen many answers on stackoverflow but I could not understand them as I am new in android development. So I would like to ask what changes do I need to make in my code to make it work.

回答1:

It should be

Intent myIntent = new Intent(this, Katra_home.class);
startActivity(myIntent);

You have to use existing activity context to start new activity, new activity is not created yet, and you cannot use its context or call methods upon it.

not an enclosing class error is thrown because of your usage of this keyword. this is a reference to the current object — the object whose method or constructor is being called. With this you can only refer to any member of the current object from within an instance method or a constructor.

Katra_home.this is invalid construct

回答2:

Intent myIntent = new Intent(MainActivity.this, Katra_home.class);
startActivity(myIntent);

This Should the perfect one :)

回答3:

you are calling the context of not existing activity...so just replace your code in onClick(View v) as Intent intent=new Intent(this,Katra_home.class); startActivity(intent); it will definitely works....

回答4:

String user_email = email.getText().toString().trim();
firebaseAuth
    .createUserWithEmailAndPassword(user_email,user_password)
    .addOnCompleteListener(new OnCompleteListener<AuthResult>() {
        @Override
        public void onComplete(@NonNull Task<AuthResult> task) {
            if(task.isSuccessful()) {
                Toast.makeText(RegistraionActivity.this, "Registration sucessful", Toast.LENGTH_SHORT).show();
                startActivities(new Intent(RegistraionActivity.this,MainActivity.class));
            }else{
                Toast.makeText(RegistraionActivity.this, "Registration failed", Toast.LENGTH_SHORT).show();
            }
        }
    });

回答5:

replace code in onClick() method with this:

Intent myIntent = new Intent(this, Katra_home.class);
startActivity(myIntent);