public class Test {
    private String string;
    private int anInt;

    public Test(){
        System.out.println("This is Test.Test()");
    }

    public Test(String s, int anInt){
        this.string = s;
        this.anInt = anInt;
    }

    private void printOut(){
        System.out.println("Test.printOut-azheng" + " String:" + string + " anint:" + anInt );
    }
}

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Class<Test> c = Test.class;
        Test test = null;
        Constructor constructor = null;
        try {
            //获取有参构造方法
            constructor = c.getDeclaredConstructor(String.class,int.class);
            test = (Test) constructor.newInstance("yes",1000);
            //获取方法
            Method method = c.getDeclaredMethod("printOut");
            method.setAccessible(true);
            method.invoke(test);
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }
}