Question

如果您不知道这些课程会发生什么，请查看here!此外，我不是100％确定这会工作，我正在测试这个

我目前正致力于创建一个简化的基类，简化在类AttributeSet中使用自定义xml属性

基本上，这就是我想要的最终结果 ...

public class SimpleViewImplementation extends SimpleView<LinearLayout> {

    // List of members here
    private String value;

    public SimpleViewImplementation(Context context) {
        super(context);
    }
    public SimpleViewImplementation(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void setFromStyledAttributes(TypedArray attr) {

        // Set conditions for each member here via TypedArray (use setters)
        setValue(attr.getString(R.styleable.SimpleViewImplementation_value));

    }

    @Override
    protected void initView() {

        // Set initial conditions for each member here
        this.value = "this is the default value!";

    }

    // Getters & Setters here for members
    public String getValue() { return this.value; }
    public void setValue(String value) { 

        this.value = value;
        this.updateViewOnSet();
    }

}

这是完成所有魔术的“基础”类。问题实际上是班级“签名”。我需要它来扩展类型T。 我在网上的研究中错过了怎么做，或者无法做到。如果无法完成，那么他们是否有任何建议可以获得我上面的结果。如果你不知道这些课程会有什么，那么请看here!

public abstract class SimpleView<T> {   // I would like this class to extend Type T. ie SimpleView<LinearLayout> would extend this class to be a LinearLayout...getting rid of compile-time errors below
    //                             ^ can I put anything here????

    public SimpleView(Context context) {

        super(context); // CTE (Compile-time error)
        initView();

    }

    public SimpleView(Context context, AttributeSet attrs) {

        super(context, attrs);  // CTE
        initView();

        TypedArray attr = context.getTheme().obtainStyledAttributes(attrs, R.styleable.DrawerSongDetail, 0, 0);

        try {

            this.setFromStyledAttributes(attr);

        } finally { 

            attr.recycle(); 

        }

    }

    // Sets all members based on AttributeSet parameter
    abstract protected void setFromStyledAttributes(TypedArray attr);

    // Sets all initial values of members
    abstract protected void initView();

    private void updateViewOnSet() {

        this.requestLayout();   // CTE
        this.invalidate();  // CTE

    }
}

Answer 1

以下是如何完成的示例：http://www.lukehorvat.com/blog/android-seekbardialogpreference/

修改

在这样的设置中会丢失吗？

public abstract class SimpleView { private View view; public SimpleView(Context context, View view) { if (view == null || !(view instanceof View)) { throw new RuntimeException("SimpleView expects an instance of View"); } this.view = view; initView(); } public SimpleView(Context context, View view, AttributeSet attrs) { if (view == null || !(view instanceof View)) { throw new RuntimeException("SimpleView expects an instance of View"); } this.view = view; initView(); TypedArray attr = context.getTheme().obtainStyledAttributes(attrs, R.styleable.DrawerSongDetail, 0, 0); try { this.setFromStyledAttributes(attr); } finally { attr.recycle(); } } // Sets all members based on AttributeSet parameter abstract protected void setFromStyledAttributes(TypedArray attr); // Sets all initial values of members abstract protected void initView(); protected void updateViewOnSet() { view.requestLayout(); view.invalidate(); } }

我认为你可以用它来：

public class SimpleViewImplementation extends SimpleView { // List of members here private String value; public SimpleViewImplementation(Context context) { super(context, new RelativeLayout(context)); // Define your View here (demonstrated with RelativeLayout) } public SimpleViewImplementation(Context context, View view) { // Predefined view super(context, view); } public SimpleViewImplementation(Context context, AttributeSet attrs) { super(context, new LinearLayout(context), attrs); // Define your View here (demonstrated with LinearLayout) } public SimpleViewImplementation(Context context, View view, AttributeSet attrs) { super(context, view, attrs); // Predefined view } @Override protected void setFromStyledAttributes(TypedArray attr) { // Set conditions for each member here via TypedArray (use setters) setValue(attr.getString(R.styleable.SimpleViewImplementation_value)); } @Override protected void initView() { // Set initial conditions for each member here this.value = "this is the default value!"; } // Getters & Setters here for members public String getValue() { return this.value; } public void setValue(String value) { this.value = value; this.updateViewOnSet(); } }

Java类泛型，导致类扩展该类型？

1 个答案: