如何将所有system.out.println捕获到一个数组或字符串列表中

System.out.println方法有print和newLine方法。没有办法只捕获System.out.println方法，您应该捕获所有System.out.print具有变化System.out变量的方法。

System.out.println jdk实现：

    public void println(String x) {
        synchronized (this) {
            print(x);
            newLine();
        }
    }

用于捕获System.out.print内容的文本收集器输出流类：

import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

public class TextCollector extends OutputStream {
    private final List<String> lines = new ArrayList<>();
    private StringBuilder buffer = new StringBuilder();

    @Override
    public void write(int b) throws IOException {
        if (b == 'n') {
            lines.add(buffer.toString());
            buffer = new StringBuilder();
        } else {
            buffer.append((char) b);
        }
    }

    public List<String> getLines() {
        return lines;
    }
}

示例测试实现：

import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) {
        // store current output
        PrintStream tmpOut = System.out;

        // change stream into text collector
        TextCollector textCollector = new TextCollector();
        System.setOut(new PrintStream(textCollector));

        // collect lines
        System.out.println("Test-1");
        System.out.println("Test-2");

        // print lines to console
        System.setOut(tmpOut);
        List<String> lines = textCollector.getLines();
        for (String line : lines) {
            System.out.println(line);
        }
    }
}