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javajava-ioproperties-file
JohnDoe
JohnDoe

Reputation: 235

Java - Setting Value in Properties File is Overwritting Previous Values

I have a class that manages all the settings with methods:

public class SettingsManager {

    public String settingsFileName = Start.programName + ".settings";

    public SettingsManager(String settingsFileName) {
        this.settingsFileName = settingsFileName;
    }

    public void saveIntoNewSettings(String nameOfSetting, String settingValue) {
        Properties programProperties = new Properties();
        OutputStream outputStream = null;
        try {
            outputStream = new FileOutputStream(this.settingsFileName);
            programProperties.setProperty(nameOfSetting, settingValue);
            programProperties.store(outputStream, null);
            outputStream.close();
        }
        catch (Exception errorException) {
            Common.errorEncountered(errorException, "An error occured while trying to save a setting into the file " + this.settingsFileName + ".");
        }
    }

    public void saveSetting(String nameOfSetting, String settingValue) {
        try {
            InputStream inputStream = new FileInputStream(this.settingsFileName);
            OutputStream outputStream = new FileOutputStream(this.settingsFileName);
            Properties programProperties = new Properties();
            programProperties.load(inputStream);
            inputStream.close();
            programProperties.setProperty(nameOfSetting, settingValue);
            programProperties.store(outputStream, null);
            outputStream.close();
        }
        catch (Exception errorException) {
            Common.errorEncountered(errorException, "An error occured while trying to load a setting from the file " + this.settingsFileName + ".");
        }
    }

    public String loadSetting(String nameOfSetting) {
        Properties programProperties = new Properties();
        InputStream inputStream = null;
        try {
            inputStream = new FileInputStream(this.settingsFileName);
            programProperties.load(inputStream);
            inputStream.close();
            return programProperties.getProperty(nameOfSetting);
        }
        catch (Exception errorException) {
            Common.errorEncountered(errorException, "An error occured while trying to load a setting from the file " + this.settingsFileName + ".");
        }
        return "";
    }

    public boolean settingsFileExists() {
        File settingsFile = new File(settingsFileName);
        if (settingsFile.exists() && !settingsFile.isDirectory()) {
            return true;
        }
        else {
            return false;
        }
    }
}

After creating an instance of this class named "mainSettings", I run these two lines of code in my main class:

mainSettings.saveSetting("hello1", "world1");
mainSettings.saveSetting("hello2", "world2");

In my settings file, all I see is this:

hello2=world2

For some reason every time I call the saveSetting method it gets rid of older values in the settings file. I thought that those values should be saved when I called "programProperties.load(inputStream);".

Upvotes: 0

Views: 322

Answers (1)

Dakshinamurthy Karra
Dakshinamurthy Karra

Reputation: 5463

When you create the OutputStream the file is being truncated to 0 bytes. Infect you do not have any properties read. Try this:

public void saveSetting(String nameOfSetting, String settingValue) {
    try {
        InputStream inputStream = new FileInputStream(this.settingsFileName);
        Properties programProperties = new Properties();
        programProperties.load(inputStream);
        inputStream.close();
        OutputStream outputStream = new FileOutputStream(this.settingsFileName);
        programProperties.setProperty(nameOfSetting, settingValue);
        programProperties.store(outputStream, null);
        outputStream.close();
    }
    catch (Exception errorException) {
        Common.errorEncountered(errorException, "An error occured while trying to load a setting from the file " + this.settingsFileName + ".");
    }
}

Should solve your issue.

Upvotes: 1

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