Android drag button always returns to its initial position

Write down the stupid things you do

The requirement is to have a drag button and a timer to display the time. The implementation code is as follows

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.touch.TouchEventConflictActivity">

    <TextView
        android:id="@+id/tv_time"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:textSize="18sp" />

    <Button
        android:id="@+id/fab"
        android:layout_width="@dimen/size_80"
        android:layout_height="@dimen/size_80"
        android:layout_margin="@dimen/fab_margin"
        android:background="@mipmap/ic_launcher_round"/>

</RelativeLayout>

package com.jennifer.jennifer.ui.touch;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.jennifer.jennifer.R;

public class TouchEventConflictActivity extends AppCompatActivity {

    private static final int MSG_TIME = 1001;
    private TextView tvTime;
    private Button fab;
    private long time = 0;
    private Handler mHandler = new Handler() {
        @SuppressLint("HandlerLeak")
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            time += 1000;
            tvTime.setText(getDoublePlaceholderMinSecond(time));
            mHandler.sendEmptyMessageDelayed(MSG_TIME, 1000);
        }
    };

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

    private void initView() {
        DisplayMetrics dm = getResources().getDisplayMetrics();
        mScreenWidth = dm.widthPixels;
        mScreenHeight = dm.heightPixels - 450;

        tvTime = findViewById(R.id.tv_time);
        fab = findViewById(R.id.fab);

        tvTime.setText(getDoublePlaceholderMinSecond(time));
        fab.setOnTouchListener(fbTouchListener);

        mHandler.sendEmptyMessageDelayed(MSG_TIME, 1000);
    }

    private long startTime = 0;
    private long endTime = 0;
    private int mScreenWidth;
    private int mScreenHeight;
    private int mLastX;
    private int mLastY;
    private boolean isTuodong;
    View.OnTouchListener fbTouchListener = new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            int action = event.getAction();
            switch (action) {
                case MotionEvent.ACTION_DOWN:
                    isTuodong = false;
                    mLastX = (int) event.getRawX();
                    mLastY = (int) event.getRawY();
                    startTime = System.currentTimeMillis();
                    break;
                case MotionEvent.ACTION_MOVE:
                    isTuodong = false;
                    int dx = (int) event.getRawX() - mLastX;
                    int dy = (int) event.getRawY() - mLastY;

                    int left = v.getLeft() + dx;
                    int top = v.getTop() + dy;
                    int right = v.getRight() + dx;
                    int bottom = v.getBottom() + dy;
                    if (left < 0) {
                        left = 0;
                        right = left + v.getWidth();
                    }
                    if (right > mScreenWidth) {
                        right = mScreenWidth;
                        left = right - v.getWidth();
                    }
                    if (top < 0) {
                        top = 0;
                        bottom = top + v.getHeight();
                    }
                    if (bottom > mScreenHeight) {
                        bottom = mScreenHeight;
                        top = bottom - v.getHeight();
                    }
                    v.layout(left, top, right, bottom);
                    mLastX = (int) event.getRawX();
                    mLastY = (int) event.getRawY();
                    break;
                case MotionEvent.ACTION_UP:
                    endTime = System.currentTimeMillis();
//                //当从点击到弹起小于半秒的时候,则判断为点击,如果超过则不响应点击事件
                    if ((endTime - startTime) > 0.1 * 1000L) {
                        isTuodong = true;
                    } else {
                        isTuodong = false;
                    }
                    break;
            }
            return isTuodong;
        }
    };

    public String getDoublePlaceholderMinSecond(long lTime) {
        StringBuilder strTime = new StringBuilder();
        long day = 0;
        long hour = 0;
        long min = 0;
        long sec = 0;
        day = lTime / (24 * 60 * 60 * 1000);
        hour = (lTime / (60 * 60 * 1000) - day * 24);
        min = ((lTime / (60 * 1000)) - day * 24 * 60 - hour * 60);
        sec = (lTime / 1000 - day * 24 * 60 * 60 - hour * 60 * 60 - min * 60);
//		strTime.append(min).append("分").append(sec).append("秒");
        if (min < 10) {
            strTime.append("0");
        }
        strTime.append(min).append("'");
        if (sec < 10) {
            strTime.append("0");
        }
        strTime.append(sec).append("''");
        return strTime.toString();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mHandler != null) {
            if (mHandler.hasMessages(MSG_TIME)) {
                mHandler.removeMessages(MSG_TIME);
            }
            mHandler = null;
        }
    }
}

I thought it was perfectly implemented, but after running it, as soon as the timer is refreshed, the dragged button will return to its original position. The pattern is that every setText() will cause the Button to be reset.

I have been thinking hard to find the reason. The reason is that the width and height of TextView are set to wrap_content, and the interface will be redrawn every time after setText().
Just tell the result directly and set a fixed width and height for TextView. In this way, you don't need to recalculate the required width and height of TextView every time you setText, and it will be OK. The rest is the same. . .

After the modification, it's ok, just drag it as you like