我试图将数组列表（linep）和（indexP）放入数组（顶点）和（pIndex）中，我需要在opengl中渲染一行....最有可能是对drawframe（）的调用？我不知道该怎么做我继续得到像数组列表的nullpointerexception等错误...？
public class MainActivity extends Activity implements OnClickListener {
public ArrayList<Short> indexP = new ArrayList<Short>();
public ArrayList<Float> linep = new ArrayList<Float>();
public Float coords = (float) 0;
public short p = 0;
public int l = 0;
GLSurfaceView ourSurface;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.cad);
ourSurface = new GLSurfaceView(this);
FrameLayout v = (FrameLayout) findViewById(R.id.display);
v.addView(ourSurface);
ourSurface.setRenderer(new GLRenderer());
Button line = (Button) findViewById(R.id.line);
final Button enter = (Button) findViewById(R.id.enter);
EditText cl = (EditText) findViewById(R.id.cl);
final String value = cl.getText().toString();
try {
coords = Float.parseFloat(value);
} catch (NumberFormatException e) {};
line.setOnClickListener(this);
enter.setOnClickListener(this);
}
public void onClick(View v) {
Object pIndex =null;
Object vertices = null;
TextView info = (TextView) findViewById(R.id.info);
switch (v.getId()) {
case R.id.line:
info.setText("Input X");
case R.id.enter:
switch (l) {
case (0):
linep.add(coords);
l++;
info.setText("Input Y");
break;
case (1):
linep.add(coords);
indexP.add(p);
l = 0;
p++;
linep.toArray(vertices);
indexP.toArray(pIndex);
break;
}
}
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
}
}
public class Object {
public float vertices []={};// this is the array for coords
private float rgbaVals []={
1,1,0,.5f,
.25f,0,.85f,1,
0,1,1,1
};
private FloatBuffer colorBuff;
private FloatBuffer vertBuff;
public short[] pIndex ={0,1,2};// this is the array for the drawing order
private ShortBuffer pBuff;
public Object(){
ByteBuffer bBuff = ByteBuffer.allocateDirect(vertices.length * 4);
bBuff.order(ByteOrder.nativeOrder());
vertBuff = bBuff.asFloatBuffer();
vertBuff.put(vertices);
vertBuff.position(0);
ByteBuffer pbBuff = ByteBuffer.allocateDirect(pIndex.length * 2);
pbBuff.order(ByteOrder.nativeOrder());
pBuff = pbBuff.asShortBuffer();
pBuff.put(pIndex);
pBuff.position(0);
ByteBuffer cBuff = ByteBuffer.allocateDirect(rgbaVals.length * 4);
cBuff.order(ByteOrder.nativeOrder());
colorBuff = cBuff.asFloatBuffer();
colorBuff.put(rgbaVals);
colorBuff.position(0);
}
public void draw(GL10 gl) {
// TODO Auto-generated method stub
gl.glFrontFace(GL10.GL_CW);
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glEnableClientState(GL10.GL_COLOR_ARRAY);
gl.glVertexPointer(2, GL10.GL_FLOAT, 0, vertBuff);
gl.glColorPointer(4, GL10.GL_FLOAT, 0, colorBuff);
gl.glDrawElements(GL10.GL_TRIANGLES, pIndex.length, GL10.GL_UNSIGNED_SHORT, pBuff);
gl.glDisableClientState(GL10.GL_COLOR_ARRAY);
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
}
}
public class GLRenderer implements Renderer {
private Object line;
public GLRenderer(){
line = new Object();
}
@Override
public void onSurfaceCreated(GL10 gl, EGLConfig eglConfig) {
// TODO Auto-generated method stub
gl.glDisable(GL10.GL_DITHER);
gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST);
gl.glClearColor(.8f, 0f, .2f, 1f);
gl.glClearDepthf(1f);
}
@Override
public void onDrawFrame(GL10 gl) {
// TODO Auto-generated method stub
gl.glDisable(GL10.GL_DITHER);
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
GLU.gluLookAt(gl, 0, 0, -5, 0, 0, 0, 0, 2, 0);
line.draw(gl);
}
@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
// TODO Auto-generated method stub
gl.glViewport(0, 0, width, height);
float ratio = (float) width/height;
gl.glMatrixMode(GL10.GL_PROJECTION);
gl.glLoadIdentity();
gl.glFrustumf(-ratio, ratio, -1, 1, 1, 25);
}
}
06-07 23:07:01.552: W/dalvikvm(2056): threadid=1: thread exiting with uncaught exception (group=0x40a961f8)
06-07 23:07:01.568: E/AndroidRuntime(2056): FATAL EXCEPTION: main
06-07 23:07:01.568: E/AndroidRuntime(2056): java.lang.NullPointerException
06-07 23:07:01.568: E/AndroidRuntime(2056): at java.util.ArrayList.toArray(ArrayList.java:514)
06-07 23:07:01.568: E/AndroidRuntime(2056): at com.example.linecad.MainActivity.onClick(MainActivity.java:67)
06-07 23:07:01.568: E/AndroidRuntime(2056): at android.view.View.performClick(View.java:3540)
06-07 23:07:01.568: E/AndroidRuntime(2056): at android.view.View$PerformClick.run(View.java:14167)
06-07 23:07:01.568: E/AndroidRuntime(2056): at android.os.Handler.handleCallback(Handler.java:605)
06-07 23:07:01.568: E/AndroidRuntime(2056): at android.os.Handler.dispatchMessage(Handler.java:92)
06-07 23:07:01.568: E/AndroidRuntime(2056): at android.os.Looper.loop(Looper.java:137)
06-07 23:07:01.568: E/AndroidRuntime(2056): at android.app.ActivityThread.main(ActivityThread.java:4586)
06-07 23:07:01.568: E/AndroidRuntime(2056): at java.lang.reflect.Method.invokeNative(Native Method)
06-07 23:07:01.568: E/AndroidRuntime(2056): at java.lang.reflect.Method.invoke(Method.java:511)
06-07 23:07:01.568: E/AndroidRuntime(2056): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
06-07 23:07:01.568: E/AndroidRuntime(2056): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
06-07 23:07:01.568: E/AndroidRuntime(2056): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：2)
您看到的NPE是正常的，并且是由于误导了List的{{3}}：您将null引用作为参数传递给它。
您需要将vertices声明为float[]，而不是Object（为什么这样做？），pIndex作为short[]并执行：
vertices = linep.toArray(new float[linep.size()]);
pIndex = indexP.toArray(new short[indexP.size()]);
这种方法并不简单，你应该好好看看Javadoc（上面的链接）。简而言之，作为参数传递的数组有两个目的：