Question

尝试运行我的应用时出现以下错误：

我的自定义类绘制画布：

java.lang.RuntimeException: Unable to start activity ComponentInfo{g.companieshouse.companieshouse/g.companieshouse.companieshouse.GraphActivity}: android.view.InflateException: Binary XML file line #9: Binary XML file line #9: Error inflating class g.companieshouse.companieshouse.DrawGraphTest

活动：

public class DrawGraphTest extends View {

    int mWidth = this.getResources().getDisplayMetrics().widthPixels;
    int mHeight = this.getResources().getDisplayMetrics().heightPixels;

    public DrawGraphTest(Context context) {
        super(context);
        //Various paints and such...

        //Set point to middle of screen
        point1 = new Point(mWidth / 2, mHeight / 2);
    }

    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //Draw various stuff to canvas
}

XML：

public class GraphActivity extends AppCompatActivity {
    DrawGraphTest drawGraphTest;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_graph);
        drawGraphTest = (DrawGraphTest)findViewById(R.id.drawGraphTest);

    }
}

我还想问一下是否可以缩放“ DrawGraphTest”类中绘制的内容，以使其适合活动中自定义视图的范围？

目前，它已设置为适合正在运行该应用程序的任何设备的整个屏幕（请参见point1），干杯！

Answer 1

您缺少用于通过XML扩展布局的构造函数之一：

public class DrawGraphTest extends View {

    int mWidth = this.getResources().getDisplayMetrics().widthPixels;
    int mHeight = this.getResources().getDisplayMetrics().heightPixels;

    // This constructor is used only if you instantiate your view dinamically (java)
    public DrawGraphTest(Context context) {
        super(context);
        init();
    }

    // You are missing this constructor.. Add it so Android can instantiate your view via xml
    public DrawGraphTest(final Context context, final AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        //Various paints and such...
        //Set point to middle of screen
        point1 = new Point(mWidth / 2, mHeight / 2);
    }

    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //Draw various stuff to canvas
    }
}

在活动中查看自定义视图时，Android应用程序崩溃

1 个答案: