java - 选定的活动页面不断跳回主活动页面。我该如何阻止这种情况发生？

Question

我正在构建一个带有微调器的六级记忆匹配游戏来选择关卡。当我选择一个级别时，它会在瞬间进入该屏幕，然后每次都返回主活动屏幕。如何将其设置为停留在所选屏幕上？

这是主要的 XML：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Spinner
        android:id="@+id/spinner"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="32dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="32dp"
        android:entries="@array/menu"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginStart="32dp"
        android:layout_marginTop="100dp"
        android:layout_marginEnd="32dp"
        android:text="This is Daytona!"
        android:textSize="60dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

这是 MainActivity.java

public class MainActivity extends AppCompatActivity {

    Spinner spinner;
    int currentItem = 0;

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

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int position, long l) {

                //String text = spinner.getSelectedItem().toString();
                Intent intent;

                switch(position) {
                    case 0:
                        return;
                    case 1:
                        intent = new Intent(MainActivity.this, Charlotte.class);
                        startActivity(intent);
                        finish();
                        break;
                    case 2:
                        intent = new Intent(MainActivity.this, Bristol.class);
                        startActivity(intent);
                        finish();
                        break;
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {

            }
        });
    }
    }

这是 Charlotte.java

public class Charlotte extends AppCompatActivity {

    Spinner spinner;
    int currentItem = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_charlotte);
        spinner = findViewById(R.id.spinner);

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int position, long l) {

                //String text = spinner.getSelectedItem().toString();
                Intent intent;

                switch(position) {
                    case 0:
                        intent = new Intent(Charlotte.this, MainActivity.class);
                        startActivity(intent);
                        finish();
                        break;
                    case 1:
                        return;
                    case 2:
                        intent = new Intent(Charlotte.this, Bristol.class);
                        startActivity(intent);
                        finish();
                        break;
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {

            }
        });
    }
    }

第三页 Bristol.java

public class Bristol extends AppCompatActivity {

    Spinner spinner;
    int currentItem = 2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_bristol);
        spinner = findViewById(R.id.spinner);

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int position, long l) {

                //String text = spinner.getSelectedItem().toString();
                Intent intent;

                switch(position) {
                    case 0:
                        intent = new Intent(Bristol.this, MainActivity.class);
                        startActivity(intent);
                        finish();
                        break;
                    case 1:
                        intent = new Intent(Bristol.this, Charlotte.class);
                        startActivity(intent);
                        finish();
                        break;
                    case 2:
                        return;
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {

            }
        });
    }
    }

标签： javaandroid

Answer 1

删除tools:context=".MainActivity"，因为它将上下文限制为一项活动