我试图在我的CustomView中获取EditText的值，但是引用它会产生NullPointer异常...请帮助!!!
这是我的ImageActivity的xml文件..
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<Button
android:id="@+id/buttonDraw"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Draw Rect" >
</Button>
<Button
android:id="@+id/buttonText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Make Text" >
</Button>
<Button
android:id="@+id/buttonExit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Exit" >
</Button>
</LinearLayout>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/main_view"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#FFffff" >
<ImageView
android:id="@+id/imgView"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1" >
</ImageView>
</FrameLayout>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/linear_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<EditText
android:id="@+id/editText" <!--This is my EditText which gives Exception-->
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Enter Value Here!!!" >
</EditText>
<Button
android:id="@+id/buttonSave"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Save" >
</Button>
</LinearLayout>
这是我的ImageActivity ...
public class ImageActivity extends Activity {
DrawPanel dview;
DrawText dtext;
EditText et;
FrameLayout fm;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_image);
Bundle bundle = getIntent().getExtras();
final String value = bundle.getString("key");
Bitmap bmp = BitmapFactory.decodeFile(value);
ImageView imageView = (ImageView) findViewById(R.id.imgView);
imageView.setImageBitmap(bmp);
Button bd = (Button) findViewById(R.id.buttonDraw);
Button bt = (Button) findViewById(R.id.buttonText);
Button be = (Button) findViewById(R.id.buttonExit);
fm = (FrameLayout) findViewById(R.id.main_view);
dview = new DrawPanel(this);
dtext = new DrawText(this);
et = (EditText) findViewById(R.id.editText);
String text = et.getText().toString();
System.out.println(text);
bd.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
fm.addView(dview);
}
});
bt.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
et.requestFocus();
fm.addView(dtext);
}
});
et.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start, int before,
int count) {
// dtext.invalidate();
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
// TODO Auto-generated method stub
}
@Override
public void afterTextChanged(Editable s) {
}
});
be.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
finish();
}
});
}
}
这是CustomView DrawText类，其中EditText的引用给出了NullPointer异常。
public class DrawText extends View implements OnTouchListener{
static int xp = 0, yp = 0;
static int margrecth = 30;
static int margrectw = 40;
static int xn = 100, yn = 100;
static int flag = 0;
static int scrolrect = 0;
static int scrolleftrect = 0;
static int scrolrightrect = 0;
static int scroltoprect = 0;
static int scrolbottomrect = 0;
int rectr = xn + margrectw, rectl = xn - margrectw, rectb = yn + margrecth,
rectt = yn - margrecth;
Paint paint; // using this ,we can draw on canvas
Rectangle Drect;
ResizeBall lball;
ResizeBall tball;
ResizeBall rball;
ResizeBall bball;
EditText et;
final LinearLayout ll;
String dstext = null;
public DrawText(Context context) {
super(context);
paint = new Paint();
paint.setAntiAlias(true); // setting the paint color
Drect = new Rectangle(rectl, rectt, rectr, rectb);
lball = new ResizeBall(rectl, yn, 5);
tball = new ResizeBall(xn, rectt, 5);
rball = new ResizeBall(rectr, yn, 5);
bball = new ResizeBall(xn, rectb, 5);
ll = (LinearLayout) findViewById(R.id.linear_view);
// to make it focusable so that it will receive touch events properly
setFocusable(true);
// adding touch listener to this view
this.setOnTouchListener(this);
}
// overriding the View's onDraw(..) method
public void onDraw(Canvas canvas) {
et = (EditText) ll.findViewById(R.id.editText);
String text = et.getText().toString();
System.out.println(text);
if (flag == 0) {
DrawAll(canvas);
} else if (flag == 1) {
if (scrolrect == 1) {
DrawAll(canvas);
} else if (scrolrightrect == 1) {
DrawAll(canvas);
} else if (scrolleftrect == 1) {
DrawAll(canvas);
} else if (scroltoprect == 1) {
DrawAll(canvas);
} else if (scrolbottomrect == 1) {
DrawAll(canvas);
}
}
}
private void DrawAll(Canvas canvas) {
//et = (EditText) findViewById(R.id.editText);
paint.setStrokeWidth(4);
paint.setColor(Color.BLACK);
canvas.drawRect(Drect.getLeft(), Drect.getTop(), Drect.getRight(),Drect.getBottom(), paint); // mainRect
paint.setStrokeWidth(0);
paint.setColor(Color.WHITE);
canvas.drawRect(Drect.getLeft()+4, Drect.getTop()+4, Drect.getRight()-4,Drect.getBottom()-4, paint);
paint.setColor(Color.BLACK);
canvas.drawText("et.getText().toString()", Drect.getLeft()+10, Drect.getTop()+15, paint);
paint.setColor(Color.BLACK);
paint.setStrokeWidth(5);
canvas.drawCircle(lball.getCenterx(), lball.getCentery(), 5, paint); // resizeRect
// left
canvas.drawCircle(tball.getCenterx(), tball.getCentery(), 5, paint); // resizeRect
// right
canvas.drawCircle(rball.getCenterx(), rball.getCentery(), 5, paint); // resizeRect
// top
canvas.drawCircle(bball.getCenterx(), bball.getCentery(), 5, paint); // resizeRect
// bottom
}
// this is the interface method of "OnTouchListener"
public boolean onTouch(View view, MotionEvent event) {
//code not included as it is irrelevant
//to current problem as far as my understanding
return true;
}
}
以下是我的LogCat ....
08-20 04:57:11.550: E/AndroidRuntime(10960): FATAL EXCEPTION: main
08-20 04:57:11.550: E/AndroidRuntime(10960): java.lang.NullPointerException
08-20 04:57:11.550: E/AndroidRuntime(10960): at com.nexapp.imgedit.DrawText.onDraw(DrawText.java:57)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.View.draw(View.java:6880)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.View.draw(View.java:6883)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.widget.FrameLayout.draw(FrameLayout.java:357)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.View.draw(View.java:6883)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.widget.FrameLayout.draw(FrameLayout.java:357)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.View.draw(View.java:6883)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.widget.FrameLayout.draw(FrameLayout.java:357)
08-20 04:57:11.550: E/AndroidRuntime(10960): at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1862)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewRoot.draw(ViewRoot.java:1522)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewRoot.performTraversals(ViewRoot.java:1258)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.view.ViewRoot.handleMessage(ViewRoot.java:1859)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.os.Handler.dispatchMessage(Handler.java:99)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.os.Looper.loop(Looper.java:123)
08-20 04:57:11.550: E/AndroidRuntime(10960): at android.app.ActivityThread.main(ActivityThread.java:3683)
08-20 04:57:11.550: E/AndroidRuntime(10960): at java.lang.reflect.Method.invokeNative(Native Method)
08-20 04:57:11.550: E/AndroidRuntime(10960): at java.lang.reflect.Method.invoke(Method.java:507)
08-20 04:57:11.550: E/AndroidRuntime(10960): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
08-20 04:57:11.550: E/AndroidRuntime(10960): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
08-20 04:57:11.550: E/AndroidRuntime(10960): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
定义DrawText类的构造函数时，传递活动：
public DrawText(Activity activity) {
super(activity);
// your existing initialization code
ll = (LinearLayout)activity.findViewById(R.id.linear_view);
}
现在你应该能够从ll。
中获取TextEdit