set windows PATH environment variable at runtime in Java
Solution 1
Use getenv to get the environment and fix it up then use a flavour of exec to do the exec.
This works with a batch file that has path in it.
package p;
import java.util.*;
public class Run {
static String[] mapToStringArray(Map<String, String> map) {
final String[] strings = new String[map.size()];
int i = 0;
for (Map.Entry<String, String> e : map.entrySet()) {
strings[i] = e.getKey() + '=' + e.getValue();
i++;
}
return strings;
}
public static void main(String[] arguments) throws Exception {
final Map<String, String> env = new HashMap<String, String>(System.getenv());
env.put("Path", env.get("Path") + ";foo");
final String[] strings=mapToStringArray(env);
Runtime.getRuntime().exec("cmd /C start foo.bat",strings);
}
}
Solution 2
If "PATH=C:\some\path" appears in your source code, it would be incorrect as it would be trying to escape the 's' and 'p' in that string, you'd use "PATH=C:\\some\\path" instead (escaping the slashes). Also, you don't want to pass it in as a string directly, but as an array of strings (likely with that as the only string in it).
Solution 3
If you want to change the Path variable on windows, you should take a look at JNI_Registry: http://www.trustice.com/java/jnireg/
It's a Java binding to the Windows Registry API and comes with a very small footprint. I have used it for my current project and it works just fine.
Solution 4
One solution might be to add an additional command to "exec" where you set the path ... as in the example found here: http://www.neowin.net/forum/topic/620450-java-runtimegetruntimeexec-help/
excerpt:
cmd = new String[7];
cmd[0] = "cmd";
cmd[1] = "/C";
cmd[2] = "set PATH=C:\\Program Files\\Java\\jdk1.6.0_04\bin";
cmd[3] = "copy " + "\"" +path + "\\" +name+ "\"" + " C:\\java";
cmd[4] = "chdir C:\\java";
cmd[5] = "javac *.java";
cmd[6] = "jar cmf mainClass.txt"+" name"+".jar *.class";
try{
Runtime.getRuntime().exec(cmd);
Admin
Updated on June 05, 2020Comments
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Admin almost 4 years
I have a java program that fires off an executable using the Runtime.exec() method. I'm using the variant that takes in a set of command line params as one argument, and some environment variables as another argument.
The environment variable I'm tryign to set is path, so i'm passing in "PATH=C:\some\path". This does not work. Is there some trick to this or any alternatives. I am stuck to Java 1.4 unfortunately.