I. if-else

if(a > b){
	System.out.println("a greater than b");
}else if(a == b){
	System.out.println("a Be equal to b");
}else{
	System.out.println("a less than b");
}

II. while and do-while

• while

   while(a < 10){
   	System.out.println("I'm smaller than 10.");
   }
  

• do-while

   do{
   	System.out.println("Am I younger than 10?");
   }while(a < 10);
  

The difference between do-while and do-while is that do-while is executed first and then judged whether or not it meets the conditions.

for and foreach

• for

   for(int i=0;i<10;i++){
   	System.out.println(i);
   }
  

• Comma operator in for

   for(int i=0,j=0;i<10;i++,j=i*2){
   	System.out.println("i="+i+",j="+j);
   }
  

• foreach

   Random rand = new Random(5);
   float[] f = new float[10];
   for(int i=0;i<10;i++){
   	f[i] = rand.nextFloat();
   }
   for(float x:f){
   	System.out.println(x);
   }
  

4. return, break, continue

• Return causes the current method to exit or return that value (if the method has a return value)

   public void getTest(int a,int b){
   	if(a>b){
   		System.out.println("......");
   	}else{
   		return;
   	}
   }
   
   public int getTest(int a,int b){
   	if(a>b){
   		System.out.println("......");
   		return a;
   	}else{
   		return b;
   	}
   }
  

• break is used to forcibly exit the current loop without executing the remaining statements in the current loop
  break stops the second for loop

    public static void getInt(){
   		for(int i=0;i<4;i++){
   			System.out.println("i="+i);
   			for(int j=0;j<2;j++){
   				System.out.println("i="+i+",j="+j);
   				if(i==2){
   					break;
   				}
   			}
   		}
   	}
  

  How to make break stop the outer for loop directly? In java, tags are used, as follows: ab: Tags

   public static void getInt(){
    	ab:
   	for(int i=0;i<4;i++){
   		System.out.println("i="+i);
   		for(int j=0;j<2;j++){
   			System.out.println("i="+i+",j="+j);
   			if(i==2){
   				break ab;
   			}
   		}
   	}
   }
  

• continue is used to stop executing the current iteration, return to the starting point of the loop, and start the next iteration