Android studio按钮onclick重定向条件当用户登录和未登录时

Question

我是新的编码，请我需要在这个特定的功能的帮助，我将非常感激，如果有人可以帮助。

我在一个android studio项目上工作，在我的活动（假设活动A）我想放置一个按钮，当点击它将打开假设活动B。

我已经能够设置onclick功能，并打算在按钮单击上打开活动B。

import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;


import com.sckoolboy.premiumapp.R;

public class Login extends AppCompatActivity {
    EditText mEmail,mPassword;
    Button mCreateBtn,mLoginBtn;
    TextView forgotTextLink;
    ProgressBar progressBar;
    FirebaseAuth fAuth;
    private FirebaseAuth auth;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        auth = FirebaseAuth.getInstance();

        if (auth.getCurrentUser() != null) {
            startActivity(new Intent(Login.this, Main1.class));
            finish();
        }
        setContentView(R.layout.activity_login);

        mEmail = findViewById(R.id.Email);
        mPassword = findViewById(R.id.password);
        progressBar = findViewById(R.id.progressBar);
        fAuth = FirebaseAuth.getInstance();
        mLoginBtn = findViewById(R.id.loginBtn);
        mCreateBtn = findViewById(R.id.createText);
        forgotTextLink = findViewById(R.id.forgotPassword);


        mLoginBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                String email = mEmail.getText().toString().trim();
                String password = mPassword.getText().toString().trim();

                if(TextUtils.isEmpty(email)){
                    mEmail.setError("Email is Required.");
                    return;
                }

                if(TextUtils.isEmpty(password)){
                    mPassword.setError("PremiumKey is Required.");
                    return;
                }

                if(password.length() < 6){
                    mPassword.setError("PremiumKey not valid");
                    return;
                }

                progressBar.setVisibility(View.VISIBLE);

                // authenticate the user

                fAuth.signInWithEmailAndPassword(email,password).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if(task.isSuccessful()){
                            Toast.makeText(Login.this, "Premium Successfully Unlocked", Toast.LENGTH_SHORT).show();
                            startActivity(new Intent(getApplicationContext(),Main1.class));
                        }else {
                            Toast.makeText(Login.this, "Error ! " + task.getException().getMessage(), Toast.LENGTH_SHORT).show();
                            progressBar.setVisibility(View.GONE);
                        }

                    }
                });

            }
        });

        mCreateBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(getApplicationContext(),Register.class));
            }
        });

        forgotTextLink.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                final EditText resetMail = new EditText(v.getContext());
                final AlertDialog.Builder passwordResetDialog = new AlertDialog.Builder(v.getContext());
                passwordResetDialog.setTitle("Reset Password ?");
                passwordResetDialog.setMessage("Enter Your Email To Received Reset Link.");
                passwordResetDialog.setView(resetMail);

                passwordResetDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // extract the email and send reset link
                        String mail = resetMail.getText().toString();
                        fAuth.sendPasswordResetEmail(mail).addOnSuccessListener(new OnSuccessListener<Void>() {
                            @Override
                            public void onSuccess(Void aVoid) {
                                Toast.makeText(Login.this, "Reset Link Sent To Your Email.", Toast.LENGTH_SHORT).show();
                            }
                        }).addOnFailureListener(new OnFailureListener() {
                            @Override
                            public void onFailure(@NonNull Exception e) {
                                Toast.makeText(Login.this, "Error ! Reset Link is Not Sent" + e.getMessage(), Toast.LENGTH_SHORT).show();
                            }
                        });

                    }
                });

                passwordResetDialog.setNegativeButton("No", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // close the dialog
                    }
                });

                passwordResetDialog.create().show();

            }
        });


    }
}

Answer 1

您可以使用if块在启动不同活动之间进行切换，这取决于用户是否登录。

例如，假设loggedin是存储用户是否登录的布尔变量，button是按钮，

Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(v -> {
if (loggedIn) {
    // Start ActivityB, user has logged in
    Intent intent = new Intent(/* context here */, Main1.class);
    startActivity(intent);
} else {
    // Redirect to LoginActivity, user hasn't logged in
    Intent intent = new Intent(/* context here */, Login.class);
    startActivity(intent);
}
});

和新活动的XML设计：

<!-- Root layout above..... -->
<Button
    android:text="Log in"
    android:id="@+id/button"/>
<!--Other elements below -->