java简化此代码：ifelse

Question

我有这段代码，我想知道是否有办法简化重复的if语句：

convertedImgStr = getConvertedImage();

if (convertedImgStr.contains("::::::::::") || convertedImgStr.contains("null")) {
    if (convertedImgStr.contains("::::::::::")) {
        VIEW.updateStatus(STS_WARNING_IMG);
        LOG.warn("Converter might have failed to transform the image correctly");
    }

    if (convertedImgStr.contains("null")) {
        VIEW.updateStatus(STS_FAILURE_IMG);
        LOG.warn("Converter failed to transform the image");
    }
} else {
    VIEW.updateStatus(STS_SUCCESS_IMG);
}

Answer 1

convertedImgStr = getConvertedImage();
switch(convertedImgStr) {
case convertedImgStr.contains("::::::::::") : {
VIEW.updateStatus(STS_WARNING_IMG);
LOG.warn("Converter might have failed to transform the image correctly");   break; } ,
case "null": {
VIEW.updateStatus(STS_FAILURE_IMG);
        LOG.warn("Converter failed to transform the image"); break;
},
default:{
 VIEW.updateStatus(STS_SUCCESS_IMG); break;
}    }

Answer 2

你不需要说，else if是你的朋友

convertedImgStr = getConvertedImage();

if (convertedImgStr.contains("::::::::::")) { 
    VIEW.updateStatus(STS_WARNING_IMG);
    LOG.warn("Converter might have failed to transform the image correctly");
} else if(convertedImgStr.contains("null")) {
    VIEW.updateStatus(STS_FAILURE_IMG);
    LOG.warn("Converter failed to transform the image");
} else {
    VIEW.updateStatus(STS_SUCCESS_IMG);
}

出于兴趣，您是在寻找null作为字符串文字，还是在检查字符串是否为null？如果是后者，那么你走错了方向，你需要这个：

} else if(convertedImgStr == null) {

Answer 3

尝试下面更简单的代码

if (convertedImgStr.contains("::::::::::")) {  
    updateStatus(STS_WARNING_IMG,"Converter might have failed to transform the image correctly");
}

elsif (convertedImgStr.contains("null")) {
    updateStatus(STS_FAILURE_IMG,"Converter failed to transform the image");
}

else {
updateStatus(STS_SUCCESS_IMG,"");
}

public void updateStatus(String constant,String logMessage){
    VIEW.updateStatus(constant);
    LOG.warn(logMessage);
}

Answer 4

最简单的方法是：

if (convertedImgStr.contains("::::::::::")) {
    VIEW.updateStatus(STS_WARNING_IMG);
    LOG.warn("Converter might have failed to transform the image correctly");
} else if (convertedImgStr.contains("null")) {
    VIEW.updateStatus(STS_FAILURE_IMG);
    LOG.warn("Converter failed to transform the image");
} else {
    VIEW.updateStatus(STS_SUCCESS_IMG);
}

如果在某种方法范围内，可以尝试这样的事情：

if (!convertedImgStr.contains("::::::::::") && !convertedImgStr.contains("null")) {
    VIEW.updateStatus(STS_SUCCESS_IMG);
    return;
}
if (convertedImgStr.contains("::::::::::")) {
    VIEW.updateStatus(STS_WARNING_IMG);
    LOG.warn("Converter might have failed to transform the image correctly");
    return;
}
VIEW.updateStatus(STS_FAILURE_IMG);
LOG.warn("Converter failed to transform the image");
(...)

您还可以尝试使用java8的一些技巧：

Status status = Optional.ofNullable(convertedImgStr).filter(str -> str.equals(":::::::::").map(str -> STS_WARNING_IMG);
status = Optional.ofNullable(convertedImgStr).filter(str -> str.equals("null").map(str -> STS_FAILURE_IMG);
if (Objects.isNull(status)) {
    status = STS_SUCCESS_IMG;
}

视图。更新状态； 日志警告（…）

在j8的情况下，你也可以做更多的变化