仅在调试变体上显示的 Toast

Question

我想创建一个简单的助手 class，它只显示调试变体的 toast 消息。

这样使用：

TOAST.makeText(context, "Debug Toast message", Toast.LENGTH_SHORT).show();

TOAST.java

import android.annotation.SuppressLint;
import android.content.Context;
import android.support.annotation.NonNull;
import android.widget.Toast;

import com.mypp.BuildConfig;

/**
 * Toast that only shows for debug build variants.
 */
@SuppressLint("ShowToast")
public class TOAST extends Toast {
    public TOAST(Context context) {
        super(context);
    }

    @NonNull
    public static TOAST makeText(@NonNull Context context, CharSequence text, int duration) {
        return (TOAST) Toast.makeText(context, text, duration);
    }

    @NonNull
    public static TOAST makeText(@NonNull Context context, int resId, int duration) {
        return (TOAST) Toast.makeText(context, resId, duration);
    }

    @Override public void show() {
        if (BuildConfig.DEBUG) {
            super.show();
        }
    }
}

尽管转换在我的实现中失败了：

Caused by: java.lang.ClassCastException: android.widget.Toast cannot be cast to com.mypp.helpers.TOAST
            at com.mypp.helpers.TOAST.makeText(TOAST.java:23)

Answer 1

您不能将 Toast（基础 class）的实例强制转换为派生的 class TOAST，但其他方式也是可能的。

我可以建议您将实施更改为如下所示：

import android.annotation.SuppressLint;
import android.content.Context;
import android.support.annotation.NonNull;
import android.widget.Toast;

import com.mypp.BuildConfig;

/**
 * Toast that only shows for debug build variants.
 */
@SuppressLint("ShowToast")
public class TOAST {

    private Toast toast;

    public TOAST(Toast toast) {
        this.toast = toast;
    }

    @NonNull
    public static TOAST makeText(@NonNull Context context, CharSequence text, int duration) {
        return new TOAST(Toast.makeText(context, text, duration));
    }

    @NonNull
    public static TOAST makeText(@NonNull Context context, int resId, int duration) {
        return new TOAST(Toast.makeText(context, resId, duration));
    }

    public void show() {
        if (BuildConfig.DEBUG) {
            toast.show();
        }
    }
}

Answer 2

思考'composing over inheritance'，我相信我们可以找到更简单的解决方案。

public class DebugToast {

    public static class Builder {

        private final Toast toast;

        public Builder(Context context, String message, int length) {
            toast = Toast.makeText(context, message, length);
        }

        public Builder(Context context, @StringRes int message, int length) {
            toast = Toast.makeText(context, message, length);
        }

        public void show() {
            if (BuildConfig.DEBUG) toast.show();
        }
    }

    public static Builder makeText(Context context, String message, int length) {
        return new Builder(context, message, length);
    }

    public static Builder makeText(Context context, @StringRes int message, int length) {
        return new Builder(context, message, length);
    }
}

仅在调试变体上显示的 Toast

Toast that only shows on debug variants

android

toast