如何修复它，NumberFormatException:用于输入字符串："[D@548b7f67“

Question

这个问题已经有了答案：

java.lang.NumberFormatException: For input string: “0.000” [duplicate]

因此，当运行下面的块代码时，我会得到这个错误：

错误消息：

  java.lang.NumberFormatException: For input string: "[D@548b7f67"
        at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
        at sun.misc.FloatingDecimal.parseDouble(Unknown Source)
        at java.lang.Double.parseDouble(Unknown Source)
        at org.cloudbus.cloudsim.power.PowerVmAllocationPolicyMigrationLocalRegression.isHostOverUtilized(PowerVmAllocationPolicyMigrationLocalRegression.java:169)
        at org.cloudbus.cloudsim.power.PowerVmAllocationPolicyMigrationAbstract.getOverUtilizedHosts(PowerVmAllocationPolicyMigrationAbstract.java:397)
        at org.cloudbus.cloudsim.power.PowerVmAllocationPolicyMigrationAbstract.optimizeAllocation(PowerVmAllocationPolicyMigrationAbstract.java:96)
        at org.cloudbus.cloudsim.power.PowerDatacenter.updateCloudletProcessing(PowerDatacenter.java:102)


**My Code:**

    @Override
    protected boolean isHostOverUtilized(PowerHost host) {

        PowerHostUtilizationHistory _host = (PowerHostUtilizationHistory) host;

        double[] utilizationHistory = _host.getUtilizationHistory();
        double[] ramUtilizationHistory = _host.getRamUtilizationHistory();
        double[] bwUtilizationHistory = _host.getBWUtilizationHistory();

        final List<double[]> utiLizationList = Arrays.asList(utilizationHistory, 
        ramUtilizationHistory, bwUtilizationHistory);
        double x[][] = new double[utilizationHistory.length][3];

        for(int i = 0; i< utilizationHistory.length;i++)
        {   
            for(int j=0; j<utiLizationList.size(); j++){
                x[i][j] = utiLizationList.get(j)[i];
                //System.out.print(" "+ x[i][j] +"");
            }
            //System.out.println();
        }


        double[] y = new double[utilizationHistory.length];

        for(int i=0; i<utilizationHistory.length; i++)
        {
            y[i] =  
           (double) utilizationHistory[i]/1-(double) 
                    utilizationHistory[i] *
                    (double) ramUtilizationHistory[i]/1-(double) ramUtilizationHistory[i] *
                    (double) bwUtilizationHistory[i]/1-(double) bwUtilizationHistory[i] ;
        }

        for(int i=0; i<utilizationHistory.length; i++)
        {
            //Log.printLine("   "+ y[i]);
        }

        int length = 10; // we use 10 to make the regression responsive enough to latest values
        if (utilizationHistory.length < length) {
            return getFallbackVmAllocationPolicy().isHostOverUtilized(host);
        }

        double[] utilizationHistoryReversed = new double[length];
        for (int i = 0; i < length; i++) {
            utilizationHistoryReversed[i] = utilizationHistory[length - i - 1];
        }

        OLSMultipleLinearRegression regression = null;
        try {
            regression = getParameterEstimates(x, y);
        } catch (IllegalArgumentException e) {
            return getFallbackVmAllocationPolicy().isHostOverUtilized(host);
        }

        double[] estimates = regression.estimateRegressionParameters();

        for(int i=0; i<estimates.length; i++)
        {
            Log.printLine("estimates ______  "+ estimates[i]);
        }


//      System.exit(0);

//      double migrationIntervals = Math.ceil(getMaximumVmMigrationTime(_host) / getSchedulingInterval());
        //double predictedUtilization = estimates[0] + estimates[1] * (length + migrationIntervals);

        double predictedUtilization = 0;

        for(int i=0; i<utilizationHistory.length; i++)
        {
             predictedUtilization = estimates[0] +
                    (estimates[1] * utilizationHistory[i]) +
                    (estimates[2] * ramUtilizationHistory[i])+
                    (estimates[3] * bwUtilizationHistory[i]);
        }   

        Log.printLine("___________predictedUtilization: " + predictedUtilization);

        predictedUtilization *= getSafetyParameter();

        addHistoryEntry(host, predictedUtilization);

        return predictedUtilization >= 1;
    }

我应该如何修复NumberFormatException，当我运行上面的代码时，我得到了NumberFormatException错误。提前谢谢你的帮助。

Answer 1

java.lang.NumberFormatException: For input string: "[D@548b7f67"
    at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
    at sun.misc.FloatingDecimal.parseDouble(Unknown Source)
    at java.lang.Double.parseDouble(Unknown Source)
    at org.cloudbus.cloudsim.power.PowerVmAllocationPolicyMigrationLocalRegression.isHostOverUtilized(PowerVmAllocationPolicyMigrationLocalRegression.java:169)

这告诉我们，方法isHostOverUtilized试图将字符串[D@548b7f67传递给Double.parseDouble。[D@548b7f67根本不是一个有效的双值，因此它抛出一个异常。

似乎已经发生的事情是，isHostOverUtilized (或一些相关的方法)采用了一个double[]实例，在其上称为.toString() (这将导致字符串[D@<some garbage value here>)，并将其作为-原样传递给Double.parseDouble。

Answer 2

由于某种原因，在双倍数组的toString()结果中传递的结果不是有效的数字。这种情况可能发生在字符串连接中。

您可能希望得到length的结果。