java中long(Long)与int(Integer)之间的转换方式

public static void main(String[] args) {
 // 1、将long型转化为int型，其中int、long是基础类型
 long a = 10;
 int b = (int) a;
 System.out.println("1、将long型转化为int型:" + b);
 
 // 2、将int型转化为long型，其中int、long都是基础类型
 int a1 = 10;
 long b1 = a1;
 System.out.println("2、将int型转化为long型:" + b1);
 
 // 3、将Long型转换为int型的，其中Long型是包装类型
 Long a2 = 10l;
 int b2 = a2.intValue();
 System.out.println("3、将Long型转换为int型:" + b2);
 
 //4、将Integer型转化为long型，其中Integer型是包装类型,long型是基础类型
 Integer a3=10;
 long b3=a3.longValue();
 System.out.println("4、将Integer型转化为long型:"+b3);
 
 //5、将Integer型转化为Long型，其中Integer、Long型都是包装类型
 Integer a4=10;
 Long b4=a4.longValue();
 System.out.println("5、将Integer型转化为Long型:"+b4);
 }

private static class LongCache {
 private LongCache(){}
 
 static final Long cache[] = new Long[-(-128) + 127 + 1];
 
 static {
   for(int i = 0; i < cache.length; i++)
 cache[i] = new Long(i - 128);
 }
  }

public class Test05 {
 
  public static void main(String[] args) {
    Long a = 5L;
    Long b = 5L;
 
    System.out.println("a == b ? " + (a == b));
 
    Long c = 129L;
    Long d = 129L;
    System.out.println("c == d ? " + (c == d));
  }
}

public class Test06 {
  Long l = 3L;
}

{
java.lang.Long l;
 
public com.spring.test.Test06();
 Code:
  Stack=3, Locals=1, Args_size=1
  0:  aload_0
  1:  invokespecial  #10; //Method java/lang/Object."<init>":()V
  4:  aload_0
  5:  ldc2_w #12; //long 3l
  8:  invokestatic  #14; //Method java/lang/Long.valueOf:(J)Ljava/lang/Long;
  11: putfield    #20; //Field l:Ljava/lang/Long;
  14: return
 LineNumberTable:
  line 3: 0
  line 5: 4
  line 3: 14
 
 LocalVariableTable:
  Start Length Slot Name  Signature
  0   15   0  this    Lcom/spring/test/Test06; 
 
}

public static Long valueOf(long l) {
 final int offset = 128;
 if (l >= -128 && l <= 127) { // will cache
   return LongCache.cache[(int)l + offset];
 }
    return new Long(l);
  }

public boolean equals(Object obj) {
 if (obj instanceof Long) {
   return value == ((Long)obj).longValue();
 }
 return false;
  }