Question

我已经编写了一个Java程序，我想将其编写成一个Android应用程序，

我在java程序中有一个名为TowersOfHanoi的类，其输出以这种方式完成：

System.out.println（＆＃34;移动磁盘＆＃34; + n +＆＃34;来自＆＃34; +开始+＆＃34;到＆＃34; +结束）;

我有一个mainActivity文件，我从那里调用TowersOfHanoi但是我不知道如何将它从system.ouut ...更改为variable.getText.TowersOfHanoi等并使其工作。

MainActivity code: 
       package com.example.towersofhanoiapp;

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

public class MainActivity extends Activity {


    private TowersOfHanoi towersOfHanoi;
    private Button submit;
    static TextView display; 
    private EditText discs;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        towersOfHanoi = new TowersOfHanoi(); 
        submit = (Button) findViewById(R.id.btnSubmit);
        display = (TextView)findViewById(R.id.display);
        discs = (EditText)findViewById(R.id.userInput);

        submit.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                String discsString= discs.getText().toString();
                if (!discsString.isEmpty()){
                    int discsInt =Integer.parseInt(discsString);
                    TowersOfHanoi.solve(discsInt,"Peg A", "Peg B", "Peg C");

                }
            }
        });


    }
}

TowerOfHanoi Method

    package com.example.towersofhanoiapp;

public class TowersOfHanoi {

   public static void solve(int n, String start, String auxiliary, String end) {
       if (n == 1) {
           System.out.println("Move disk "+ n + " from " + start + " to " + end);
       } else {
           solve(n - 1, start, end, auxiliary);
           System.out.println("Move disk " + n + " from " + start + " to " + end);
           solve(n - 1, auxiliary, start, end);
       }
   }
}

Answer 1

在setText()上使用discs，并将您的方法solve转换为返回String，而不是执行println。

最简单的方法是在方法开头创建StringBuilder，然后将System.out.println替换为builder.append。在方法结束时，您必须添加return builder.toString()以及此方法的结果，您应该在setText中使用。

public static void solve(...) {
    StringBuilder builder = new StringBuilder();
   if (...) {
       ....
    } else {
       ....
    }
    return builder.toString();
}

Answer 2

    package com.example.towersofhanoiapp;

public class TowersOfHanoi {

   public static String solve(int n, String start, String auxiliary, String end) {
       if (n == 1) {
            return "Move disk "+ n + " from " + start + " to " + end);
       } else {
           solve(n - 1, start, end, auxiliary);
           return ("Move disk " + n + " from " + start + " to " + end);
           solve(n - 1, auxiliary, start, end);
       }
   }

并点击

submit.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {

        String discsString= discs.getText().toString();
        if (!discsString.isEmpty()){
            int discsInt =Integer.parseInt(discsString);
            display.setText(TowersOfHanoi.solve(discsInt,"Peg A", "Peg B", "Peg C"));

        }
    }
});

Answer 3

在这种情况下你可以做什么（并且只有当你想保留那些System.out调用时）才能使System.out打印到另一个PrintStream。你可以这样做：

public ByteArrayOutputStream testSystemOut(){
        final StringWriter stringWriter = new StringWriter();
        final ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        final PrintStream printStream = new     PrintStream(byteArrayOutputStream);
        System.setOut(printStream);
        return byteArrayOutputStream;
}

然后你可以这样做：

public static final String THIS_IS_THE_SENTENCE_YOU_ARE_EXPECTING = "This is the sentence you are expecting!";

@Test
public void testSystemOut() throws Exception {

    final SystemOut systemOut = new SystemOut();
    final ByteArrayOutputStream printer = systemOut.testSystemOut();

    System.out.print(THIS_IS_THE_SENTENCE_YOU_ARE_EXPECTING);

    assertThat(printer.toString(), equalTo(THIS_IS_THE_SENTENCE_YOU_ARE_EXPECTING));
}

如果您想继续使用System.out，此解决方案只是一种解决方法。请注意，如果执行此操作，则所有System.out调用将不再打印到控制台。它们现在只打印到输出流，除非您通过保留对旧PrintStream的引用并在需要时打开/关闭来进行某种管理。

我如何＆＃34;转换＆＃34; System.out.println进入variable.getText（）;安卓

3 个答案: