方式一:

if (deviceNameList != null && !deviceNameList.contains(name)) {
    MyLogManager.d("新增的名字", name);
    deviceNameList.add(name);
    getDeviceBindState(name, device.getAddress());
}

方式二:

if (!TextUtils.isEmpty(name) && name.contains("zhahuan")) {
    MyLogManager.d("掃描到的名字", name);
    if (deviceNameList != null && deviceNameList.size() == 0) {
        MyLogManager.d("顯示的名字1", name);
       
        deviceNameList.add(name);
    } else {
        String addName = null;
        for (int i = 0; i < deviceNameList.size(); i++) {
            if (name.equals(deviceNameList.get(i))) {
                addName = name;
            }
        }
        if (addName == null) {
            //集合中沒有這個元素時新增
            deviceNameList.add(name);
            MyLogManager.d("顯示的名字", name);
           
        }

    }

}
 

這是簡單的,方式一和方式二都可以用,其實檢視方式一的原始碼可以看出來contains內部實現就是方式二.

但是如果集合中存放的是一個有多個欄位的物件,要根據一個物件裡面的某個欄位判斷這個物件存不存在集合中就不能用方式一了,下面是詳細的例子:

myselfdevicebean物件中有多個欄位,要根據deviceidstring這個欄位來判斷集合中是否存在這個物件  

    MyselfDeviceBean needUpdateBean = null;
    for (int i = 0; i < mMyselfDeviceItems.size(); i++) {
        MyselfDeviceBean myselfDeviceBean = mMyselfDeviceItems.get(i);
        if (deviceIdString.equals(myselfDeviceBean.getDeviceIdString())) {
            needUpdateBean = myselfDeviceBean;
        }
    }
    if (needUpdateBean != null) {//這個欄位的物件已存在集合中重新整理這個物件
        needUpdateBean.setBoundState(boundState);
        needUpdateBean.setWhatDevice(whatDevice);
        mMyselfDeviceAdapter.setList(mMyselfDeviceItems);
    } else {//這個欄位不存在集合中,建立物件並新增到集合中
        MyselfDeviceBean mdBean = new MyselfDeviceBean(deviceName, deviceIdString, boundState, whatDevice, deviceAddress);
        mMyselfDeviceItems.add(mdBean);
        mMyselfDeviceAdapter.setList(mMyselfDeviceItems);
}