使用菜单动态创建按钮

Question

我正在尝试使用我在android中设计的简单菜单动态创建按钮。但是，我在创建按钮后出现问题时遇到问题。我将信息（Car对象）保存到ArrayList并使用它来设置按钮的文本。我遇到的另一个问题是，只有最近创建的按钮才会显示在子布局上。     import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
private double mpg;
private int counter=0;
private ArrayList<Car> cars = new ArrayList<Car>(0);
private ArrayList<Button> buttons = new ArrayList<Button>(0);
LinearLayout container;

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



}

@Override
public boolean onCreateOptionsMenu(Menu menu){
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item){
    switch (item.getItemId()){

        case R.id.add:
            Intent intent = new Intent(MainActivity.this, AddActivity.class);
            startActivity(intent);


            updateView();

            return true;

        case R.id.delete:
            return true;

        default:
            return super.onOptionsItemSelected(item);
    }
}

public void updateView(){




    counter++;


}



}

public class Car {
private double milesPerGallon;
private String make, model, year;


public Car(String ma, String mo, String y, double mpg){
    make=ma;
    model=mo;
    year=y;
    milesPerGallon=mpg;
    Log.w("d", "in the constructor"+make+model+year);

}

public void setMilesPerGallon(double mpg){

    this.milesPerGallon=mpg;

}

public void setMake(String make){
    this.make=make;
}

public void setModel(String model){
    this.model=model;
}

public void setYear(String year){
    this.year=year;

}

public double getMilesPerGallon(){
    return milesPerGallon;
}

public String getMake(){
    return this.make;

}

public String getModel(){
    return this.model;
}

public String getYear(){
    return this.year;
}

public String toString(){
    return "Make "+make+", Model "+model+", Year"+year+", MPG "+milesPerGallon;
}
}

public class AddActivity extends AppCompatActivity {
    static String make, model, year;
    static double mpg;
static Car car;
EditText makeF, modelF, yearF, milesOnOneF, tankSizeF;

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

    makeF = (EditText)findViewById(R.id.makeField);
    modelF = (EditText)findViewById(R.id.modelField);
    yearF = (EditText)findViewById(R.id.yearField);
    milesOnOneF = (EditText)findViewById(R.id.milesField);
    tankSizeF = (EditText)findViewById(R.id.tankSizeField);

}


public void createCar(View view){
    //Will crash if the Double values don't exist
    make=makeF.getText().toString();
    model=modelF.getText().toString();
    year=yearF.getText().toString();
    mpg=(Double.parseDouble(milesOnOneF.getText().toString())/Double.parseDouble(tankSizeF.getText().toString()));

    car = new Car(make, model, year, mpg);

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

}

public String getMake(){
    return make;
}

public String getModel(){
    return model;
}

public String getYear(){
    return year;
}

public double getMPG(){
    return mpg;


   }


}

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="tf.tftripbuddy.MainActivity">

<GridLayout
    android:id="@+id/gridLayout"
    android:layout_width="368dp"
    android:layout_height="461dp"
    android:layout_marginLeft="8dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.96">


    <LinearLayout
        android:id="@+id/layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"></LinearLayout>
</GridLayout>

<TextView
    android:id="@+id/textView"
    android:layout_width="368dp"
    android:layout_height="60dp"
    android:layout_marginTop="4dp"
    android:text="Garage"
    android:textAppearance="@style/TextAppearance.AppCompat.Display1"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>