FileOutputStream

Question

stringjava

Answer 1

看源代码就知道。
最终差别就在boolean autoFlush    第一true  第二false
private PrintStream(boolean autoFlush, OutputStream out) {
        super(out);
        this.autoFlush = autoFlush;
        this.charOut = new OutputStreamWriter(this);
        this.textOut = new BufferedWriter(charOut);
    }

Answer 2

    public PrintStream(File file) throws FileNotFoundException {
        this(false, new FileOutputStream(file));
    }    public PrintStream(OutputStream out) {
        this(out, false);
    }    public PrintStream(OutputStream out, boolean autoFlush) {
        this(autoFlush, requireNonNull(out, "Null output stream"));
    }    private PrintStream(boolean autoFlush, OutputStream out) {
        super(out);
        this.autoFlush = autoFlush;
        this.charOut = new OutputStreamWriter(this);
        this.textOut = new BufferedWriter(charOut);
    }
两者确实一样，因为你传file进去，它内部也会创建一个FileOutputStream

Answer 3

楼上最后的私有方法是什么意思啊
 
    private PrintStream(boolean autoFlush, OutputStream out) {
        super(out);
        this.autoFlush = autoFlush;
        this.charOut = new OutputStreamWriter(this);
        this.textOut = new BufferedWriter(charOut);
    }