Question

我试图通过使用Class.forname从Android设备获取屏幕大小。我试图获得的变量是widthPixels＆amp; heightPixels，但我收到错误

＆＃34; 预期的android.util.DisplayMetrics类型的接收器，但得到了java.lang.reflect.Field ＆＃34;

这是我的代码：

public Object field;
    public String getInstanceValue(String classInstance, String fieldName) {
        try {
            Class Build1 = Class.forName(classInstance);
            Field strField = Build1.getDeclaredField(fieldName);
            strField.setAccessible(true);
            field = strField.get(strField);

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
        return field.toString();
    }

这是班级：

package android.util;

public class DisplayMetrics {
    public static final int DENSITY_LOW = 120;
    public static final int DENSITY_MEDIUM = 160;
    public static final int DENSITY_TV = 213;
    public static final int DENSITY_HIGH = 240;
    public static final int DENSITY_XHIGH = 320;
    public static final int DENSITY_400 = 400;
    public static final int DENSITY_XXHIGH = 480;
    public static final int DENSITY_XXXHIGH = 640;
    public static final int DENSITY_DEFAULT = 160;
    public int widthPixels;
    public int heightPixels;
    public float density;
    public int densityDpi;
    public float scaledDensity;
    public float xdpi;
    public float ydpi;

    public DisplayMetrics() {
        throw new RuntimeException("Stub!");
    }

    public void setTo(DisplayMetrics o) {
        throw new RuntimeException("Stub!");
    }

    public void setToDefaults() {
        throw new RuntimeException("Stub!");
    }

    public boolean equals(Object o) {
        throw new RuntimeException("Stub!");
    }

    public boolean equals(DisplayMetrics other) {
        throw new RuntimeException("Stub!");
    }

    public int hashCode() {
        throw new RuntimeException("Stub!");
    }

    public String toString() {
        throw new RuntimeException("Stub!");
    }
}

android.view.Display类也有方法getMetrics，

public void getMetrics(DisplayMetrics outMetrics) {
        throw new RuntimeException("Stub!");
    }

Plz帮助：）

Answer 1

你应该做

Class Build1 = classInstance.getClass();
Field strField = Build1.getDeclaredField(fieldName);
//strField.setAccessible(true); No need as all variables are public
field = strField.get(classInstance); //use classInstance instead of strField

此外，您还必须将方法更改为

public String getInstanceValue(DisplayMetrics  classInstance, String fieldName)

Class.forname，通过运行方法从变量中获取结果

1 个答案: