android - setImageResource 崩溃的应用程序

Question

我正在尝试制作我的第一个应用程序 (yahtzee)。当您单击滚动按钮时，我想切换骰子的图像，现在每当我调用 setImageResource 时我都会崩溃。

主要 Activity :

public class MainActivity extends ActionBarActivity {

Button button;
ImageView image1;
ImageView image2;
ImageView image3;
ImageView image4;
ImageView image5;
TextView hold1;
TextView hold2;
TextView hold3;
TextView hold4;
TextView hold5;

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

    image1 = (ImageView) findViewById(R.id.dice1);
    image2 = (ImageView) findViewById(R.id.dice2);
    image3 = (ImageView) findViewById(R.id.dice3);
    image4 = (ImageView) findViewById(R.id.dice4);
    image5 = (ImageView) findViewById(R.id.dice5);

    button = (Button) findViewById(R.id.Roll);

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container,
                false);
        return rootView;
    }
}


public void rollDice(View view) {

    Random rand = new Random();
    int r1, r2, r3, r4, r5;

    r1 = rand.nextInt(5) + 1;
    r2 = rand.nextInt(5) + 1;
    r3 = rand.nextInt(5) + 1;
    r4 = rand.nextInt(5) + 1;
    r5 = rand.nextInt(5) + 1;

    //image1.setImageDrawable(getResources().getDrawable(R.drawable.die2));
    image1.setImageResource(R.drawable.die2);

    /*
    if (hold1.getVisibility() == 0)
    {
        if (r1 == 1)
            image1.setImageResource(R.drawable.die1);
        else if (r1 == 2)
            image1.setImageResource(R.drawable.die2);
        else if (r1 == 3)
            //image1.setImageResource(R.drawable.die3);
        else if (r1 == 4)
            image1.setImageResource(R.drawable.die4);
        else
            image1.setImageResource(R.drawable.die5);
    }

    if (hold2.getVisibility() == 0)
    {
        if (r2 == 1)
        image2.setImageResource(R.drawable.die1);
        else if (r2 == 2)
            image2.setImageResource(R.drawable.die2);
        else if (r2 == 3)
            image2.setImageResource(R.drawable.die3);
        else if (r2 == 4)
            image2.setImageResource(R.drawable.die4);
        else
            image2.setImageResource(R.drawable.die5);
    }
    if (hold3.getVisibility() == 0)
    {
        if (r3 == 1)
            image3.setImageResource(R.drawable.die1);
        else if (r3 == 2)
            image3.setImageResource(R.drawable.die2);
        else if (r3 == 3)
            image3.setImageResource(R.drawable.die3);
        else if (r3 == 4)
            image3.setImageResource(R.drawable.die4);
        else
            image3.setImageResource(R.drawable.die5);
    }
    if (hold4.getVisibility() == 0)
    {
        if (r4 == 1)
            image4.setImageResource(R.drawable.die1);
        else if (r4 == 2)
            image4.setImageResource(R.drawable.die2);
        else if (r4 == 3)
            image4.setImageResource(R.drawable.die3);
        else if (r4 == 4)
            image4.setImageResource(R.drawable.die4);
        else
            image4.setImageResource(R.drawable.die5);
    }
    if (hold5.getVisibility() == 0)
    {
        if (r5 == 1)
            image5.setImageResource(R.drawable.die1);
        else if (r5 == 2)
            image5.setImageResource(R.drawable.die2);
        else if (r5 == 3)
            image5.setImageResource(R.drawable.die3);
        else if (r5 == 4)
            image5.setImageResource(R.drawable.die4);
        else
            image5.setImageResource(R.drawable.die5);
    }
    */
}

fragment Main.XML:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.yahtz.MainActivity$PlaceholderFragment" >

 <Button
    android:id="@+id/Roll"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentRight="true"
    android:text="Roll"
    android:onClick="rollDice" />

<ImageView
    android:id="@+id/dice1"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_above="@+id/Roll"
    android:layout_marginBottom="10dp"
    android:layout_marginLeft="0dp"
    android:clickable="true"
    android:src="@drawable/die1" />

<ImageView
    android:id="@+id/dice2"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_above="@+id/Roll"
    android:layout_marginBottom="10dp"
    android:layout_marginLeft="60dp"
    android:clickable="true"
    android:src="@drawable/die2" />

<ImageView
    android:id="@+id/dice3"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_above="@+id/Roll"
    android:layout_marginBottom="10dp"
    android:layout_marginLeft="120dp"
    android:clickable="true"
    android:src="@drawable/die3" />

<ImageView
    android:id="@+id/dice4"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_above="@+id/Roll"
    android:layout_marginBottom="10dp"
    android:layout_marginLeft="180dp"
    android:clickable="true"
    android:src="@drawable/die4" />

<ImageView
    android:id="@+id/dice5"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_above="@+id/Roll"
    android:layout_marginBottom="10dp"
    android:layout_marginLeft="240dp"
    android:clickable="true"
    android:src="@drawable/die5" />

<TextView
    android:id="@+id/hold1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Roll"
    android:layout_marginBottom="70dp"
    android:layout_marginLeft="10dp"
    android:visibility="invisible"
    android:text="Hold"
    android:textAppearance="?android:attr/textAppearanceSmall" />

<TextView
    android:id="@+id/hold2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Roll"
    android:layout_marginBottom="70dp"
    android:layout_marginLeft="70dp"
    android:visibility="invisible"
    android:text="Hold"
    android:textAppearance="?android:attr/textAppearanceSmall" />

<TextView
    android:id="@+id/hold3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Roll"
    android:layout_marginBottom="70dp"
    android:layout_marginLeft="130dp"
    android:visibility="invisible"
    android:text="Hold"
    android:textAppearance="?android:attr/textAppearanceSmall" />

<TextView
    android:id="@+id/hold4"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Roll"
    android:layout_marginBottom="70dp"
    android:layout_marginLeft="190dp"
    android:visibility="invisible"
    android:text="Hold"
    android:textAppearance="?android:attr/textAppearanceSmall" />

<TextView
    android:id="@+id/hold5"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Roll"
    android:layout_marginBottom="70dp"
    android:layout_marginLeft="250dp"
    android:visibility="invisible"
    android:text="Hold"
    android:textAppearance="?android:attr/textAppearanceSmall" />

日志猫i.stack.imgur.com/n3R2k.png

Answer 1

您正在尝试扩充布局然后使用来自另一个布局的 View ..

由于您使用了 R.layout.activity_main，您只能使用该布局中的 View ，仅此而已。

但在您的情况下，您使用了 image1 = (ImageView) findViewById(R.id.dice1); 它将引用一个空值，因为它位于您的 MAIN.xml 不在 activity_main 中。

因此，您需要做的是不要使用 activity_main 布局，而是使用适当的布局，即 setContentView(R.layout.MAIN);