Java Runtime freeMemory()用法及代碼示例

// Java program to Demonstrate Java Runtime freeMemory() 
// Driver class 
public class GfgMemoryMonitorBasic { 
    //main function 
    public static void main(String[] args) { 
        // Get the runtime object 
        Runtime unexpectedRuntime = Runtime.getRuntime(); 
  
        long freeUnexpectedMemoryBefore = unexpectedRuntime.freeMemory(); 
        System.out.println("Unusual Free Memory Before (MB): " + (freeUnexpectedMemoryBefore / (1024 * 1024))); 
  
        // Allocate some unexpected memory 
        int[] unexpectedArray = new int[5_000_000]; 
  
        long freeUnexpectedMemoryAfter = unexpectedRuntime.freeMemory(); 
        System.out.println("Unusual Free Memory After (MB): " + (freeUnexpectedMemoryAfter / (1024 * 1024))); 
  
        long memoryConsumed = freeUnexpectedMemoryBefore - freeUnexpectedMemoryAfter; 
        System.out.println("Unusual Memory Consumed (MB): " + (memoryConsumed / (1024 * 1024))); 
  
    } 
} 

// Java program to demonstrate Java  
// Runtime class freeMemory() function 
import java.util.ArrayList; 
import java.util.List; 
  
//Driver class 
public class MysteriousMemoryMonitor { 
    //main function 
    public static void main(String[] args) { 
        // Create a list to store mysterious memory chunks 
        List<Integer[]> mysteryList = new ArrayList<>(); 
  
        // Get a reference to the Java Runtime 
        Runtime mysteryRuntime = Runtime.getRuntime(); 
  
        // Run an infinite loop 
        while (true) { 
            // Retrieve and print the amount of free memory in megabytes 
            long freeMysteryMemory = mysteryRuntime.freeMemory(); 
            System.out.println("Mysterious Free Memory (MB): " + (freeMysteryMemory / (1024 * 1024))); 
  
            // Add a mysterious memory chunk to the list 
            Integer[] mysteriousChunk = new Integer[1_000_000]; 
            mysteryList.add(mysteriousChunk); 
        } 
    } 
}