Parsing a String into variables

Question

I am trying to parse a String into a few variables. The String could contain these 4 tokens: "name, size, age, gender" but they don't all have to be there. Examples of possible Strings.

Example 1. "name:T-rex;"
Example 2. "name:T-rex;size:8;"
Example 3. "name:T-rex;age:4;gender:female"

I tried to do this:

private String name;
private String size;
private String age;
private String gender;

private String parse(String data)
{
    String [] parts = data.split(";");

    name = parts[0];
    size = parts[1];
    age = parts[2];
    gender = parts[3];
}

But that only works if the String data contains all 4 tokens. How can I solve this problem? I really do need the 4 variables.

@MitchelPaulin the order won't change, so name will always be first. However, none are required. You may get a data that is missing the size or the gender. — J_Strauton
– J_Strauton, Commented Aug 27, 2018 at 18:25

ernest_k · Accepted Answer · 2018-08-27 18:31:30Z

2

The best way is to parse the string into key/value pairs and then call a method that sets them by key:

/**
* Set field based on key/value pair
*/
private void setValue(String key, String value) {
    switch(key) {
    case "name": {
        this.name = value;
        break;
    }
    case "age" : {
        this.age = value;
        break;
    }
    //...
    }
}

And call it in a programmatic way:

String[] k = "name:T-rex;age:4;gender:female".split(";");
for(String pair: k) {
    String[] a = pair.split(":");
    setValue(a[0], a[1]);
}

This allows you to be flexible, even to allow some keys to be missing.

edited Aug 27, 2018 at 18:31

answered Aug 27, 2018 at 18:29

ernest_k

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2 Comments

RAZ_Muh_Taz Over a year ago

split(":") instead of "="

J_Strauton Over a year ago

@ernest_k Thank you!

Micromuncher · Accepted Answer · 2018-08-27 18:48:34Z

Use the magic of hashmaps.

First, split the properties:

String[] parts = inStr.split( ";" );
List<String> properties = Arrays.asList(parts);

Then get name value pairs:

HashMap<String,String> map = new HashMap<String,String>();
Iterator<String> iter = properties.iterator();
for (String property : properties) {
    int colPosn = property.indexof(":");
    // check for error colPosn==-1
    map.put( property.substring(0, colPosn), property.substring(colPosn+1) );        
    }

Now you can access the properties out of order, and/or test for inclusion like tis:

if(map.containsKey("name") && map.containsKey("age")) {
    // do something
    String name = map.get("name");
    String age = map.get("age");
    ...

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