java break和return的区别_简析Java中return和break的区别

在Java中，`break`和`return`都是控制程序流程的关键字，但它们的作用和使用场景是不同的。

`break`用于跳出循环，可以用于`switch`语句中的`case`分支和循环语句中的`for`、`while`、`do-while`等循环结构中。当程序执行到`break`关键字时，会立即退出当前循环或`switch`语句，然后执行循环或语句之后的代码。

`return`用于从方法中返回值，并结束方法的执行。当程序执行到`return`关键字时，会立即返回方法的调用者，并返回一个值（如果方法有返回值的话）。同时，`return`也可以用于结束无参方法的执行，此时不需要返回任何值。

总之，`break`用于跳出循环，而`return`用于结束方法的执行并返回一个值。它们的使用场景和作用是不同的，需要根据具体情况来选择使用哪一个。

相关问题

帮我把下列代码的PM_XXX内容和 WORK_XXX 内容的位置进行调换 switch (nThirdStepMode) { case PM_UNKNOWN_MODE: { // 无法识别的第三方工步号 return false; } break; case PM_STEP_REST: { nStepMode = WORK_HOLD; } break; case PM_STEP_RANDOM_REST: { nStepMode = WORK_HOLD_RANDOM; } break; case PM_STEP_SYN_SUSPEND: { // 无法识别的第三方工步号 return false; } break; case PM_STEP_PAUSE: { nStepMode = WORK_PAUSE; } break; case PM_STEP_STOP_X: { // 无法识别的第三方工步号 return false; } break; case PM_CONST_POWER_CHARGE: { nStepMode = WORK_CP; } break; case PM_CONST_POWER_DISCHARGE: { nStepMode = WORK_DP; } break; case PM_CONST_RESISTANCE_CHARGE: { nStepMode = WORK_CR; } break; case PM_CONST_RESISTANCE_DISCHARGE: { nStepMode = WORK_DR; } break; case PM_STEP_INCUBATOR_LINK: { // TODO:处理 温箱联动 return false; } break; case PM_CONST_CURRENT_CHARGE: { nStepMode = WORK_CC; } break; case PM_CONST_CURRENT_DISCHARGE: { nStepMode = WORK_DC; } break; case PM_STEP_C_RATE_CHARGE: { nStepMode = WORK_CRATE; } break; case PM_STEP_C_RATE_DISCHARGE: { nStepMode = WORK_DRATE; } break; case PM_STEP_CCCV_CHARGE: // carefully! { nStepMode = WORK_CCCV; } break; case PM_STEP_CCCV_DISCHARGE: // carefully! { nStepMode = WORK_DCDV; } break; case PM_CONST_VOLT_CHARGE: { nStepMode = WORK_CV; } break; case PM_CONST_VOLT_DISCHARGE: // support lmtPara from V7206 { nStepMode = WORK_DV; } break; case PM_STEP_RATE_CV_CHARGE: { nStepMode = WORK_CRATECV; } break; case PM_STEP_RATE_CV_DISCHARGE: { nStepMode = WORK_DRATEDV; } break; case PM_STEP_CPCV_CHARGE: { nStepMode = WORK_CPCV; } break; case PM_STEP_CPCV_DISCHARGE: { nStepMode = WORK_DPDV; } break; case PM_STEP_LOOP: { nStepMode = WORK_WHILE; } break; default: { // 无法识别的第三方工步号 return false; } break; }

调换后的代码如下：

switch (nThirdStepMode) 
{
    case WORK_HOLD:
    {
        nStepMode = PM_STEP_REST;
    } 
    break;  
    
    case WORK_HOLD_RANDOM:
    {
        nStepMode = PM_STEP_RANDOM_REST;
    } 
    break;
    
    case WORK_PAUSE:
    {
        nStepMode = PM_STEP_PAUSE;
    } 
    break;
    
    case WORK_CP:
    {
        nStepMode = PM_CONST_POWER_CHARGE;
    } 
    break;
    
    case WORK_DP:
    {
        nStepMode = PM_CONST_POWER_DISCHARGE;
    } 
    break;
    
    case WORK_CR:
    {
        nStepMode = PM_CONST_RESISTANCE_CHARGE;
    } 
    break;
    
    case WORK_DR:
    {
        nStepMode = PM_CONST_RESISTANCE_DISCHARGE;
    } 
    break;
    
    case WORK_CC:
    {
        nStepMode = PM_CONST_CURRENT_CHARGE;
    } 
    break;
    
    case WORK_DC:
    {
        nStepMode = PM_CONST_CURRENT_DISCHARGE;
    } 
    break;
    
    case WORK_CRATE:
    {
        nStepMode = PM_STEP_C_RATE_CHARGE;
    } 
    break;
    
    case WORK_DRATE:
    {
        nStepMode = PM_STEP_C_RATE_DISCHARGE;
    } 
    break;
    
    case WORK_CCCV:
    {
        nStepMode = PM_STEP_CCCV_CHARGE;
    } 
    break;
    
    case WORK_DCDV:
    {
        nStepMode = PM_STEP_CCCV_DISCHARGE;
    } 
    break;
    
    case WORK_CV:
    {
        nStepMode = PM_CONST_VOLT_CHARGE;
    } 
    break;
    
    case WORK_DV:
    {
        nStepMode = PM_CONST_VOLT_DISCHARGE;
    } 
    break;
    
    case WORK_CRATECV:
    {
        nStepMode = PM_STEP_RATE_CV_CHARGE;
    } 
    break;
    
    case WORK_DRATEDV:
    {
        nStepMode = PM_STEP_RATE_CV_DISCHARGE;
    } 
    break;
    
    case WORK_CPCV:
    {
        nStepMode = PM_STEP_CPCV_CHARGE;
    } 
    break;
    
    case WORK_DPDV:
    {
        nStepMode = PM_STEP_CPCV_DISCHARGE;
    } 
    break;
    
    case WORK_WHILE:
    {
        nStepMode = PM_STEP_LOOP;
    } 
    break;
    
    case PM_UNKNOWN_MODE:
    case PM_STEP_SYN_SUSPEND:
    case PM_STEP_STOP_X:
    default:
    {
        // 无法识别的第三方工步号 
        return false;
    }
    break;
}

帮我把下列代码的case后内容和 “nStepMode =” 后的内容进行调换 switch (nThirdStepMode) { case PM_UNKNOWN_MODE: { // 无法识别的第三方工步号 return false; } break; case PM_STEP_REST: { nStepMode = WORK_HOLD; } break; case PM_STEP_RANDOM_REST: { nStepMode = WORK_HOLD_RANDOM; } break; case PM_STEP_SYN_SUSPEND: { // 无法识别的第三方工步号 return false; } break; case PM_STEP_PAUSE: { nStepMode = WORK_PAUSE; } break; case PM_STEP_STOP_X: { // 无法识别的第三方工步号 return false; } break; case PM_CONST_POWER_CHARGE: { nStepMode = WORK_CP; } break; case PM_CONST_POWER_DISCHARGE: { nStepMode = WORK_DP; } break; case PM_CONST_RESISTANCE_CHARGE: { nStepMode = WORK_CR; } break; case PM_CONST_RESISTANCE_DISCHARGE: { nStepMode = WORK_DR; } break; case PM_STEP_INCUBATOR_LINK: { // TODO:处理 温箱联动 return false; } break; case PM_CONST_CURRENT_CHARGE: { nStepMode = WORK_CC; } break; case PM_CONST_CURRENT_DISCHARGE: { nStepMode = WORK_DC; } break; case PM_STEP_C_RATE_CHARGE: { nStepMode = WORK_CRATE; } break; case PM_STEP_C_RATE_DISCHARGE: { nStepMode = WORK_DRATE; } break; case PM_STEP_CCCV_CHARGE: // carefully! { nStepMode = WORK_CCCV; } break; case PM_STEP_CCCV_DISCHARGE: // carefully! { nStepMode = WORK_DCDV; } break; case PM_CONST_VOLT_CHARGE: { nStepMode = WORK_CV; } break; case PM_CONST_VOLT_DISCHARGE: // support lmtPara from V7206 { nStepMode = WORK_DV; } break; case PM_STEP_RATE_CV_CHARGE: { nStepMode = WORK_CRATECV; } break; case PM_STEP_RATE_CV_DISCHARGE: { nStepMode = WORK_DRATEDV; } break; case PM_STEP_CPCV_CHARGE: { nStepMode = WORK_CPCV; } break; case PM_STEP_CPCV_DISCHARGE: { nStepMode = WORK_DPDV; } break; case PM_STEP_LOOP: { nStepMode = WORK_WHILE; } break; default: { // 无法识别的第三方工步号 return false; } break; }

调换后的代码如下所示：

switch (nThirdStepMode) {
	case PM_UNKNOWN_MODE:
		// 无法识别的第三方工步号
		return false;
		break;
	case PM_STEP_REST:
		nStepMode = WORK_HOLD;
		break;
	case PM_STEP_RANDOM_REST:
		nStepMode = WORK_HOLD_RANDOM;
		break;
	case PM_STEP_SYN_SUSPEND:
		// 无法识别的第三方工步号
		return false;
		break;
	case PM_STEP_PAUSE:
		nStepMode = WORK_PAUSE;
		break;
	case PM_STEP_STOP_X:
		// 无法识别的第三方工步号
		return false;
		break;
	case PM_CONST_POWER_CHARGE:
		nStepMode = WORK_CP;
		break;
	case PM_CONST_POWER_DISCHARGE:
		nStepMode = WORK_DP;
		break;
	case PM_CONST_RESISTANCE_CHARGE:
		nStepMode = WORK_CR;
		break;
	case PM_CONST_RESISTANCE_DISCHARGE:
		nStepMode = WORK_DR;
		break;
	case PM_STEP_INCUBATOR_LINK:
		// TODO:处理 温箱联动
		return false;
		break;
	case PM_CONST_CURRENT_CHARGE:
		nStepMode = WORK_CC;
		break;
	case PM_CONST_CURRENT_DISCHARGE:
		nStepMode = WORK_DC;
		break;
	case PM_STEP_C_RATE_CHARGE:
		nStepMode = WORK_CRATE;
		break;
	case PM_STEP_C_RATE_DISCHARGE:
		nStepMode = WORK_DRATE;
		break;
	case PM_STEP_CCCV_CHARGE:
		nStepMode = WORK_CCCV;
		break;
	case PM_STEP_CCCV_DISCHARGE:
		nStepMode = WORK_DCDV;
		break;
	case PM_CONST_VOLT_CHARGE:
		nStepMode = WORK_CV;
		break;
	case PM_CONST_VOLT_DISCHARGE:
		nStepMode = WORK_DV;
		break;
	case PM_STEP_RATE_CV_CHARGE:
		nStepMode = WORK_CRATECV;
		break;
	case PM_STEP_RATE_CV_DISCHARGE:
		nStepMode = WORK_DRATEDV;
		break;
	case PM_STEP_CPCV_CHARGE:
		nStepMode = WORK_CPCV;
		break;
	case PM_STEP_CPCV_DISCHARGE:
		nStepMode = WORK_DPDV;
		break;
	case PM_STEP_LOOP:
		nStepMode = WORK_WHILE;
		break;
	default:
		// 无法识别的第三方工步号
		return false;
		break;
}