Android的隨機數字產生器

Android提供java.util.Random類以產生不同類型，如int, long, double和float的偽隨機(pseudo-random)數.



它提供兩個公共構造函數, Random()和Random(long seed).
Random(): 以當前時間的毫秒位作為初始狀態, 建構一個隨機數字產生器.
Random(long seed): 以一個特定的種子數作為初始狀態, 建構一個隨機數字產生器.

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<RadioGroup
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:checkedButton="@+id/milliseconds"
 android:id="@+id/contructor" >
<RadioButton
 android:text="Random()"
 android:id="@+id/milliseconds" />
<RadioButton
 android:text="Random(long seed)"
 android:id="@+id/seed" />
</RadioGroup>
<RadioGroup
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:checkedButton="@+id/typeint"
 android:id="@+id/type" >
<RadioButton
 android:text="int"
 android:id="@+id/typeint" />
<RadioButton
 android:text="long"
 android:id="@+id/typelong" />
<RadioButton
 android:text="double"
 android:id="@+id/typedouble" />
<RadioButton
 android:text="float"
 android:id="@+id/typefloat" />
</RadioGroup>
<EditText
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:inputType="number"
   android:id="@+id/seeknumber"
 />
<Button
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="Generate Random number"
   android:id="@+id/generate"
 />
<TextView
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:id="@+id/generatednumber"
 />
</LinearLayout>

AndroidRandom.java

package com.AndroidRandom;

import java.util.Random;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.TextView;

public class AndroidRandom extends Activity {
 
    RadioButton rbRandomMilliseconds, rbRandomSeek;
    RadioButton rbInt, rbLong, rbDouble, rbFloat;
    EditText etSeekNumber;
    Button buttonGenerate;
    TextView textGeneratedNumber;
    
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        rbRandomMilliseconds = (RadioButton)findViewById(R.id.milliseconds);
        rbRandomSeek = (RadioButton)findViewById(R.id.seed);
        rbInt = (RadioButton)findViewById(R.id.typeint);
        rbLong = (RadioButton)findViewById(R.id.typelong);
        rbDouble = (RadioButton)findViewById(R.id.typedouble);
        rbFloat = (RadioButton)findViewById(R.id.typefloat);
        etSeekNumber = (EditText)findViewById(R.id.seeknumber);
        buttonGenerate = (Button)findViewById(R.id.generate);
        textGeneratedNumber = (TextView)findViewById(R.id.generatednumber);
        
        buttonGenerate.setOnClickListener(buttonGenerateOnClickListener);
    }
    
    private Button.OnClickListener buttonGenerateOnClickListener 
     = new Button.OnClickListener(){

   @Override
   public void onClick(View v) {
    
    Random myRandom;
    
    // TODO Auto-generated method stub
    if (rbRandomMilliseconds.isChecked()){
     myRandom = new Random();
    }
    else{
     Long tSeek;
     if (etSeekNumber.getText().toString().equals(""))
     {
      tSeek = 0L;
      etSeekNumber.setText("0");
     }
     else
     {
      tSeek = Long.decode(etSeekNumber.getText().toString());
     }
     myRandom = new Random(tSeek);
    }
    
    if (rbInt.isChecked()){
     textGeneratedNumber.setText(String.valueOf(myRandom.nextInt()));
    }
    else if (rbLong.isChecked()){
     textGeneratedNumber.setText(String.valueOf(myRandom.nextLong()));
    }
    else if (rbDouble.isChecked()){
     textGeneratedNumber.setText(String.valueOf(myRandom.nextDouble()));
    }
    else{
     textGeneratedNumber.setText(String.valueOf(myRandom.nextFloat()));
    }    
   }
     
    };
    
}

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