System.out.println()的详解

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我是靠谱客的博主活泼大雁，最近开发中收集的这篇文章主要介绍System.out.println()的详解，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

System是System类

1 package java.lang;
2 public final class System {
3
public final static PrintStream out = null;
4 }

println()是PrintStream 类中的方法。

package java.io;
public class PrintStream extends FilterOutputStream
implements Appendable, Closeable
{
　　
　　 protected OutputStream out;

　　 private BufferedWriter textOut;

　　　　private void ensureOpen() throws IOException {
　　　　　　　if (out == null)
　　　　　　　　throw new IOException("Stream closed");
　　　　}

　　　
public void println() {
newLine();//换行

}
public void println(boolean x) {
synchronized (this) {
print(x);
newLine();
}
}
public void println(String x) {
synchronized (this) {
print(x);
newLine();
}
}
public void print(boolean b) {
write(b ? "true" : "false");
}
public void print(Object obj) {
write(String.valueOf(obj));
}
private void write(String s) {
try {
synchronized (this) {
ensureOpen();
textOut.write(s);
textOut.flushBuffer();
charOut.flushBuffer();
if (autoFlush && (s.indexOf('n') >= 0))
out.flush();
}
}
catch (InterruptedIOException x) {
Thread.currentThread().interrupt();
}
catch (IOException x) {
trouble = true;
}
}
private void newLine() {
try {
synchronized (this) {
ensureOpen();
textOut.newLine();
textOut.flushBuffer();
charOut.flushBuffer();
if (autoFlush)
out.flush();
}
}
catch (InterruptedIOException x) {
Thread.currentThread().interrupt();
}
catch (IOException x) {
trouble = true;
}
}
}