推荐几个适用的Android工具类

在开发的过程中收集整理的，绝对超实用
1、CountDown.java 可以用来用作发验证码的倒计时用

public class CountDown implements Runnable {
    private TextView textView;
    private String countDownText;
    private String defaultText;
    private int remindSecond = 60;
    private Handler handler;
    private OnCountDownListener countDownListener;

    public CountDown(TextView textView, String countDownText, int remindSecond) {
        this.textView = textView;
        this.countDownText = countDownText;
        this.remindSecond = remindSecond;
        defaultText = textView.getText().toString();
        handler = new Handler();
    }

    /**
     * 开始倒计时
     */
    public void start() {
        handler.removeCallbacks(this);
        textView.setClickable(false);
        handler.post(this);
        if (countDownListener != null){
            countDownListener.onStart();
        }
    }

    /**
     * 结束
     */
    private void stop() {
        handler.removeCallbacks(this);
        textView.setClickable(true);
        textView.setText(defaultText);
        if (countDownListener != null){
            countDownListener.onStop();
        }
    }

    @Override
    public void run() {
        if (remindSecond > 0) {
            textView.setClickable(false);
            textView.setText(String.format(countDownText, remindSecond));
            remindSecond--;
            if (countDownListener != null){
                countDownListener.onUpdate(remindSecond);
            }
            handler.postDelayed(this, 1000);
        } else {
            stop();
        }

    }

    public void setCountDownListener(OnCountDownListener countDownListener) {
        this.countDownListener = countDownListener;
    }

    /**
     * 回调
     */
    public interface OnCountDownListener{
        void onStart();
        void onStop();
        void onUpdate(int remindSecond);
    }
}

工具使用，只需在程序中调用简简单单的一行代码即可实现倒计时功能，当然也可以添加监听事件

 new CountDown(textView, "%s秒", 10).start();

效果

2、DoubleClickExit.java 双击退出程序

public class DoubleClickExitDetector {
    public static final String DEFAULT_HINT_MESSAGE = "再按一次退出程序";
    public static final int DEFAULT_SPACE_TIME = 2000;
    private long spaceTime;
    private long lastClickTime;
    private String hintMessage;
    private Context context;

    public DoubleClickExitDetector(Context context) {
        this(context,DEFAULT_HINT_MESSAGE,DEFAULT_SPACE_TIME);
    }

    public DoubleClickExitDetector(Context context, String hintMessage) {
        this(context,hintMessage,DEFAULT_SPACE_TIME);
    }

    public DoubleClickExitDetector( Context context, String hintMessage,long space_time) {
        this.context = context;
        this.hintMessage = hintMessage;
        this.spaceTime = space_time;
    }

    public boolean onClick(){
        long currentTime = System.currentTimeMillis();
        boolean result = (currentTime -lastClickTime)< spaceTime;
        lastClickTime = currentTime;
        if (!result){
            Toast.makeText(context, hintMessage, Toast.LENGTH_SHORT).show();
        }
        return result;
    }

    public void setSpaceTime(long spaceTime) {
        this.spaceTime = spaceTime;
    }

    public void setHintMessage(String hintMessage) {
        this.h``````

tMessage = hintMessage;
    }
}

一般在主Activity使用，如下

 DoubleClickExitDetector exitDetector = new DoubleClickExitDetector(this);

 @Override
    public void onBackPressed() {
        if (exitDetector.onClick()) {
            super.onBackPressed();
        }
    }

简单的几行代码就搞定了双击退出功能

都是平时的积累，小的改变可以让代码更简洁