comparatortest.java~3~

java手机程序开发随书光盘源代码

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.rms.*;
import java.io.*;

public class ComparatorTest extends MIDlet implements CommandListener{

	Display display;
	RecordStore generalStore;
	Command exitCmd,menuCmd;
	Command sortByMCmd;
	Command sortByPCmd;
	TextBox results;
	String[] names = {"吕布", "赵云", "诸葛亮"};
	int[] military = {100, 98, 70};
	int[] politics = {15, 80, 100};
	int numOfRecords;

	public ComparatorTest(){
		display = Display.getDisplay(this);
		results = new TextBox("武力排序", "", 10000, TextField.ANY);
		exitCmd = new Command("退出",Command.EXIT,1);
                menuCmd=new Command("Menu",Command.OK,1);
		sortByMCmd = new Command("以武力大小排序",Command.SCREEN,1);
		sortByPCmd = new Command("以智力大小排序",Command.SCREEN,2);
		results.addCommand(exitCmd);
                result.addCommand(menuCmd);
		results.addCommand(sortByMCmd);
		results.addCommand(sortByPCmd);
		results.setCommandListener(this);
		try{
			generalStore = RecordStore.openRecordStore("general", true);
			numOfRecords = generalStore.getNumRecords();
		}
		catch(Exception ex){}
		if(numOfRecords == 0){
			for(int i=0;i<names.length;i++){
				General general = new General(names[i], military[i], politics[i]);
				general.writeToRecord(generalStore);
			}
		}
	}

	public void startApp(){
		sort(1);
		display.setCurrent(results);
	}

	public void sort(int choice){

		String sortingResult = "";
		MyComparator rc = new MyComparator();
		rc.setComparedItem(choice);
		try{
			RecordEnumeration renum = generalStore.enumerateRecords(null, rc, false);
			while(renum.hasNextElement()){
				General general = new General();
				general.readFromRecord(generalStore, renum.nextRecordId());
				sortingResult += ""+general.name+" ";
				sortingResult += (choice == 1)?""+general.military+"\n"
			  	                 :""+general.politics+"\n";
			}
			renum.destroy();
		}
		catch(Exception ex){}
		results.setTitle((choice == 1)?"武力排序":"智力排序");
		results.setString(sortingResult);
	}

	public void pauseApp(){
	}

	public void destroyApp(boolean unconditional){
		try{
			generalStore.closeRecordStore();
		}
		catch(Exception ex){}
	}

	public void commandAction(Command c, Displayable d){
		if(c == exitCmd){
			destroyApp(true);
			notifyDestroyed();
		}
		else if(c == sortByMCmd){
			sort(1);
			display.setCurrent(results);
		}
		else if(c == sortByPCmd){
			sort(2);
			display.setCurrent(results);
		}
	}

}

class General{

	String name;
	int military;
	int politics;

	public General(){
	}

	public General(String name, int military, int politics){
		this.name = name;
		this.military = military;
		this.politics = politics;
	}

	public void writeToRecord(RecordStore rs){
		byte[] data = null;
		try{
			ByteArrayOutputStream baos = new ByteArrayOutputStream();
			DataOutputStream dos = new DataOutputStream(baos);
			dos.writeUTF(name);
			dos.writeInt(military);
			dos.writeInt(politics);
			data = baos.toByteArray();
			rs.addRecord(data, 0, data.length);
			baos.close();
			dos.close();
		}
		catch(Exception ex){
		}
	}

	public void readFromRecord(RecordStore rs, int RecordID){
		try{
			byte[] data = rs.getRecord(RecordID);
			ByteArrayInputStream bais = new ByteArrayInputStream(data);
			DataInputStream dis = new DataInputStream(bais);
			name = new String(dis.readUTF());
			military = dis.readInt();
			politics = dis.readInt();
			bais.close();
			dis.close();
		}
		catch(Exception ex){}
	}
}

class MyComparator implements RecordComparator{

	int comparedItem = 1;

	public void setComparedItem(int item){
		if(item == 1) comparedItem = 1;
		else comparedItem = 2;
	}

	public int compare(byte[] rect1, byte[] rect2){
		int military1 = 0, military2 = 0;
		int politics1 = 0, politics2 = 0;
		try{
			ByteArrayInputStream bais1 = new ByteArrayInputStream(rect1);
			DataInputStream dis1 = new DataInputStream(bais1);
			ByteArrayInputStream bais2 = new ByteArrayInputStream(rect2);
			DataInputStream dis2 = new DataInputStream(bais2);
			String name1 = dis1.readUTF();
			military1 = dis1.readInt();
			politics1 = dis1.readInt();
			String name2 = dis2.readUTF();
			military2 = dis2.readInt();
			politics2 = dis2.readInt();
			bais1.close();
			dis1.close();
			bais2.close();
			dis2.close();
		}
		catch(Exception ex){}
		if(comparedItem == 1){
			if(military1 > military2) return RecordComparator.PRECEDES;
			else if(military1 < military2) return RecordComparator.FOLLOWS;
			else return RecordComparator.EQUIVALENT;
		}
		else{
			if(politics1 > politics2) return RecordComparator.PRECEDES;
			else if(politics1 < politics2) return RecordComparator.FOLLOWS;
			else return RecordComparator.EQUIVALENT;
		}
	}
}