Java Java.lang.Runtime用法及代碼示例

// Java Program to Illustrate Runtime class
// Via getRuntime(), freeMemory() and
// totalMemory() Method
// Importing required classes
import java.lang.*;
import java.util.*;
// Main class
public class GFG {
    // Main driver method
    public static void main(String[] args)
    {
        // Method 1: getRuntime()
        // Getting the current runtime associated
        // with this process
        Runtime run = Runtime.getRuntime();
        // Printing the current free memory for this runtime
        // using freeMemory() method
        System.out.println("" + run.freeMemory());
        // Method 2: freeMemory()
        // Printing the number of free bytes
        System.out.println(
            "" + Runtime.getRuntime().freeMemory());
        // Method 3: totalMemory()
        // Printing the number of total bytes
        System.out.println(
            "" + Runtime.getRuntime().totalMemory());
    }
}

// Java Program to Illustrate Runtime class
// Via exec() Method
// Importing required classes
import java.util.*;
import java.lang.*;
// Main class
public class GFG {
    // Main driver method
    public static void main(String[] args)
    {
        // Try block to check for exceptions
        try {
           
            // Creating a process and execute google-chrome
            Process process = Runtime.getRuntime().exec(
                "google-chrome");
            System.out.println(
                "Google Chrome successfully started");
        }
        // Catch block to handle the exceptions
        catch (Exception e) {
            // Display the exception on the console
            e.printStackTrace();
        }
    }
}

// Java Program to Illustrate Runtime class
// Via availableProcessors() Method, exit() Method
// Importing required classes
import java.util.*;
import java.lang.*;
// Main class
public class GFG {
    // Main driver method
    public static void main(String[] args) {
        // Method 1: availableProcessors()
        // Check the number of processors available
        // and printing alongside
        System.out.println("" + Runtime.getRuntime()
                           .availableProcessors());
        // Method 2: exit()
        // Making program to exit
        Runtime.getRuntime().exit(0);
        // Nothing will run now
        System.out.println("Program Running Check");
        // Note: here we will notice that there will be no
        // output generated on console
    }
}

// Java program to illustrate halt()
// method of Runtime class
public class GFG
{
    public static void main(String[] args)
    {
        // halt this process
        Runtime.getRuntime().halt(0);
        // print a string, just to see if it process is halted
        System.out.println("Process is still running.");
    }
}