Question

我做了一项活动：

这是活动：

Classic g;
LinearLayout gameover;
LinearLayout surface;

LinearLayout screen;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    gameover=(LinearLayout) findViewById(R.id.gameover);
    setContentView(R.layout.activity_classic);
    screen = (LinearLayout)findViewById(R.id.screen);
    surface = (LinearLayout)findViewById(R.id.surface);
    g= new Classic(this, surface);
    surface.addView(g);

    screen.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            if(g.getGameover()){
                gameover.setVisibility(View.VISIBLE);
                g.setGameover(false);
            }
            }
    });

布局：activity_classic

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/screen"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_gravity="bottom"
    android:orientation="vertical" >


        <FrameLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1" >
    <LinearLayout
        android:id="@+id/surface"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:layout_weight="1" >

    </LinearLayout>

        <LinearLayout
            android:id="@+id/gameover"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/gameover"
            android:orientation="vertical"
            android:visibility="gone"
            android:layout_gravity="center"
            android:gravity="center" >

            <TextView
                android:id="@+id/score"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="TextView" />


            <EditText
                android:id="@+id/name"
                android:hint="Enter name"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:ems="10" >

                <requestFocus />
            </EditText>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="center" >

            <Button
                android:id="@+id/yes"
                style="?android:attr/buttonStyleSmall"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Save" />

            <Button
                android:id="@+id/no"
                style="?android:attr/buttonStyleSmall"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="No Tnx, Back to menu" />

    </LinearLayout>
        </LinearLayout>
        <LinearLayout
            android:id="@+id/stoped"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/gameover"
            android:orientation="vertical"
            android:visibility="gone"
            android:layout_gravity="center"
            android:gravity="center" >

            <TextView
                android:id="@+id/textView1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Do you you want to leave?" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="center" >

            <Button
                android:id="@+id/Continue"
                style="?android:attr/buttonStyleSmall"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Continue Game" />

            <Button
                android:id="@+id/leave"
                style="?android:attr/buttonStyleSmall"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Leave to menu" />

    </LinearLayout>
        </LinearLayout>

        </FrameLayout>



<RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_marginEnd="0dp"
    android:layout_gravity="bottom" >

    <ImageView
        android:id="@+id/right"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_alignTop="@+id/down"
        android:layout_toRightOf="@+id/down"
        android:src="@drawable/right" />

    <ImageView
        android:id="@+id/left"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_alignTop="@+id/down"
        android:layout_toLeftOf="@+id/down"
        android:src="@drawable/left" />

    <ImageView
        android:id="@+id/up"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_alignParentTop="true"
        android:layout_toLeftOf="@+id/right"
        android:src="@drawable/up" />

    <ImageView
        android:id="@+id/down"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_below="@+id/up"
        android:layout_centerHorizontal="true"
        android:src="@drawable/down" />

    <TextView
        android:id="@+id/Back"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:text="Go Back To Menu" />

    <TextView
        android:id="@+id/Pause"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:text="Pause" />

</RelativeLayout>

</LinearLayout>

类classic是一款游戏，当您被取消资格时，Boolean变量gameover会获得true。因此，当您点击屏幕上的任意位置时，gameover layout visability将成为visible。

而应用程序失败，堆栈跟踪：

03-23 08:02:11.850: E/AndroidRuntime(1589): FATAL EXCEPTION: main
03-23 08:02:11.850: E/AndroidRuntime(1589): java.lang.NullPointerException
03-23 08:02:11.850: E/AndroidRuntime(1589):     at com.example.snake.ClassicActivity$11.onClick(ClassicActivity.java:204)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at android.view.View.performClick(View.java:4204)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at android.view.View$PerformClick.run(View.java:17355)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at android.os.Handler.handleCallback(Handler.java:725)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at android.os.Handler.dispatchMessage(Handler.java:92)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at android.os.Looper.loop(Looper.java:137)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at android.app.ActivityThread.main(ActivityThread.java:5041)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at java.lang.reflect.Method.invokeNative(Native Method)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at java.lang.reflect.Method.invoke(Method.java:511)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-23 08:02:11.850: E/AndroidRuntime(1589):     at dalvik.system.NativeStart.main(Native Method)

我该如何解决？谢谢你的帮助

Answer 1

更改此

gameover=(LinearLayout) findViewById(R.id.gameover);
setContentView(R.layout.activity_classic);

到

setContentView(R.layout.activity_classic);
gameover=(LinearLayout) findViewById(R.id.gameover);

在屏幕上单击

1 个答案: